| Entries |
| Document | Title | Date |
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| 20080247034 | Fast Dynamic Gain Control in a Bidirectionally-Pumped Raman Fiber Amplifier - The present invention provides methods and apparatuses for controlling a gain of a bidirectionally-pumped Raman fiber amplifier having both forward optical pumps and backward optical pumps. The overall gain is controlled by adjusting the forward optical pumps, while the power levels of the backward optical pumps are essentially fixed. Gain circuitry operates in an opened loop configuration and uses a predetermined function relating a power variation of at least one wavelength region with a pump power adjustment for at least one forward optical pump. Two approximate linear relationships between the input signal power variations and the required pump power adjustments are utilized in controlling the Raman fiber amplifier. Each approximate linear relationship includes at least one linear coefficient that relates a power variation for a specific wavelength region and a power adjustment of a specific Raman pump. | 10-09-2008 |
| 20080266649 | Devices and method for Raman amplification and dispersion compensation - The present invention provides devices and methods for Raman amplification and dispersion compensation. According to one embodiment of the present invention, a dispersion compensating device includes a dispersion compensating fiber having a dispersion more negative than about −50 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; a Raman gain fiber having a dispersion more positive than about −40 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; and a pump source operatively coupled to the dispersion compensating fiber and the Raman gain fiber, the pump source operating at a pump wavelength, wherein the dispersion compensating fiber has a Raman Figure of Merit at the pump wavelength, and wherein the Raman gain fiber has a Raman Figure of Merit at least about equivalent to the Raman Figure of Merit of the dispersion compensating fiber, and wherein the dispersion compensating fiber and the Raman gain fiber are arranged in series between the input and the output of the device. The device provides higher Raman gain than a conventional Raman-pumped dispersion compensating device. | 10-30-2008 |
| 20080291529 | Raman pump power control for gain flattening - The present invention aims at providing a method for controlling wavelength characteristics of optical transmission powers by Raman amplification, in which the wavelength characteristics of optical transmission powers are automatically compensated without giving any losses to channel lights to thereby improve transmission characteristics, and an apparatus adopting the same. To this end, the method for controlling wavelength characteristics of optical transmission powers by Raman amplification according to the present invention supplies Raman pump light to an optical transmission path (Raman amplifying medium); compensates the wavelength characteristics of optical transmission powers caused by transmission of WDM signal light through the optical transmission path, by gain wavelength characteristics of generated Raman amplification; and monitors the wavelength characteristics of optical transmission powers after Raman amplification to thereby control the gain wavelength characteristics of Raman amplification. | 11-27-2008 |
| 20080297883 | Raman Amplifier Structure - A Raman amplifier structure ( | 12-04-2008 |
| 20090046353 | GAIN-CLAMPED OPTICAL AMPLIFYING APPARATUS USING FIBER RAMAN AMPLIFIER HAVING RAMAN CAVITY - Provided is a gain-clamped (GC) optical amplifier using a fiber Raman amplifier (FRA) having a Raman cavity. The FRA having a Raman cavity comprises a Raman fiber module (RFM) amplifying and outputting an input optical signal and a resonant cavity generating a Raman laser and a gain clamping laser (GC laser), wherein the resonant cavity is formed as a feedback loop between an input terminal and an output terminal of the RFM. Accordingly, a gain of an optical signal propagating along a core of RFM keeps a constant value regardless of input signal intensity by generating the GC laser for gain clamping between a wavelength band of the Raman laser and a gain band of input signals. | 02-19-2009 |
| 20090067038 | SEMICONDUCTOR RAMAN RING AMPLIFIER - A semiconductor-based Raman ring amplifier is disclosed. A method according to aspects of the present invention includes directing a pump optical beam having a pump wavelength and an input pump power level from an optical waveguide into a ring resonator. The optical waveguide and ring resonator are comprised in semiconductor material. A signal optical beam having a signal encoded thereon at a signal wavelength is directed from the optical waveguide into the ring resonator. The pump optical beam is resonated within the ring resonator to increase a power level of the pump optical beam to a power level sufficient to amplify the signal optical beam via stimulated Raman scattering (SRS) within the ring resonator. A free carrier concentration in the optical waveguide and the ring resonator is reduced to reduce attenuation of the pump optical beam and the signal beam. | 03-12-2009 |
| 20090091819 | Apparatus And Method For Flattening Gain Profile Of An Optical Amplifier - A change in loading conditions of fiber amplifiers in an optical communications network causes rapid variations in the gain profile of the amplifiers due to spectral hole burning and stimulated Raman scattering. An apparatus for reducing such gain profile variations is described which monitors optical signal perturbations and reacts by adjusting pump powers of the amplifiers and, or fast variable optical attenuator according to a predetermined function stored in the form of constants in controller's memory. The optical signal is monitored as total power, and the power of light after passing through one or more optical filters. The light detection is relatively fast, whereby the gain profile variations are compensated by fast controlled variable optical attenuator and pump power adjustment upon the change in loading conditions. | 04-09-2009 |
| 20090109523 | METHOD FOR REGULATING OSNR IN A FIBER OPTIC COMMUNICATION LINE USING RAMAN AMPLIFICATION - A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line satisfying limitations for real long transmission lines. The method comprises selecting the relation using a regulation function ROSNR obtained either in the form of a simplified equation, or in the form of one or more linear approximations of the function for practical ranges of the FRA gain. | 04-30-2009 |
| 20090128891 | Optical fiber amplification system - An optical fiber amplifier pumping technique based on multiple stimulated Raman scattering (SRS) for optical communication systems includes a plurality of pump signals with increasing wavelength which are injected into a fiber. The wavelengths of such pump signals are such that, in cascade, each pump signal of the plurality is amplified by the pump signal of wavelength immediately shorter, while it amplifies that with the wavelength immediately higher with the pump signal of highest wavelength which, in turn, pumps a remote rare earth doped optical fiber amplifier. | 05-21-2009 |
| 20090153950 | Phase Stabilization Device For Stimulated Brillouin Scattering Phase Conjugate Mirrors And Light Amplification Apparatus Using The Same - The object of this invention is to provide a phase stabilization device for stimulated brillouin scattering-phase conjugate mirrors and a light amplification apparatus using the phase stabilization device. A light amplification apparatus of the present invention includes a polarizer ( | 06-18-2009 |
| 20090153951 | RAMAN AMPLIFIER AND RAMAN AMPLIFIER ADJUSTMENT METHOD - A pumping unit supplies pumping light to a fiber connecting medium, a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value. | 06-18-2009 |
| 20090174930 | REGENERATIVE LASER AMPLIFIER - A laser amplifier system is presented including a pump regenerative amplifier. The amplifier generally has a cavity defined by a pair of end cavity mirrors between which an amplified pump pulse oscillates. The amplifier also includes an interaction cell with a tunable gain medium amplifies laser pulses (e.g., Raman gain). The interaction cell may be positioned within the pump amplifier cavity and an input pulse may be injected into the cavity of the amplifier to transit through the tunable gain medium of the interaction cell. A pump pulse transfers energy via interaction with the input pulse (e.g., Raman interaction) as the pulses counter-propagate through the gain medium of the interaction cell. Amplification of output laser pulses, however, is generally achieved according to the wavelength of the pump laser pulses thereby providing a wavelength dependent, or “tunable”, means for amplifying laser pulses. | 07-09-2009 |
| 20090190204 | Wavelength division multiplexing optical transmission system utilizing distributed raman amplification - The WDM optical transmission system using distributed Raman amplification, before starting operation of main signal light, transfers a plurality of lights having different wavelengths to that of the main signal light (for example Raman amplification pump lights or the like) between first and second optical transmission devices connected to opposite ends of a transmission line, monitors transmission line input and output power for each light, calculates a transmission line loss in each wavelength using the monitor results, and specifies a type of the transmission line based on a loss wavelength characteristic that can be estimated from the calculation result. Then the power of pump light provided to the transmission light is optimized in accordance with the type of transmission line. | 07-30-2009 |
| 20090190205 | RAMAN AMPLIFYING DEVICE AND CONTROL METHOD - A light amplifying device including a Raman amplifier to Raman-amplify a signal light by inputting excitation lights of a plurality of wavelengths to a transmission path through which the signal light propagates, a plurality of measuring units measuring powers of light output from the Raman amplifier in a plurality of wavelength bands included in an amplification band of the Raman amplifier, a calculating unit calculating a ratio of the respective powers measured by at least two of the plurality of measuring units, and a control unit controlling a power ratio of the respective excitation lights input to the transmission path by the Raman amplifier based on the ratio calculated by the calculating unit. | 07-30-2009 |
| 20090190206 | RAMAN AMPLIFYING DEVICE AND CONTROL METHOD - A light amplifying device including a Raman amplifier to Raman-amplify a signal light by inputting excitation lights of a plurality of wavelengths to a transmission path through which the signal light propagates, a plurality of measuring units measuring powers of light output from the Raman amplifier in a plurality of wavelength bands included in an amplification band of the Raman amplifier, a calculating unit calculating a ratio of the respective powers measured by at least two of the plurality of measuring units, and a control unit controlling a power ratio of the respective excitation lights input to the transmission path by the Raman amplifier based on the ratio calculated by the calculating unit. | 07-30-2009 |
| 20090195862 | DISTRIBUTED RAMAN AMPLIFYING SYSTEM, START-UP METHOD THEREOF, AND OPTICAL DEVICE - To obtain automatic gain control with high accuracy by including first and second light monitors, a reference light supplying unit supplying reference light of which wavelength is set within a gain band of a distributed Raman amplification and out of a wavelength band of main signal light to the optical transmission path, a first reference light monitor monitoring a power of the reference light input to the optical transmission path from one end side thereof, a second reference light monitor monitoring the power of the reference light output from the other end side of the optical transmission path, and a controlling unit controlling supply of pump light in a pump light supplying unit as well as supervising a state of the optical transmission path, based on monitor results from the first and second light monitor and the monitor results in the first and second reference light monitors. | 08-06-2009 |
| 20090195863 | Optical amplification apparatus, optical communication apparatus, and optical communication method - A Raman amplifier inputs pump light into an optical fiber (transmission path) through which an optical signal passes, to amplify the optical signal. An optical receiving unit is provided downstream of the Raman amplifier and monitors the power of the optical signal amplified by the Raman amplifier. A calculating unit determines Raman amplification gain based on the power of the optical signal monitored by the optical receiving unit, and calculates the power of a noise component included in the optical signal based on the gain. The calculating unit, in real-time, calculates the power, which varies in complicated manners depending on conditions, and outputs information concerning to the power to another apparatus at a frequency on the order of milliseconds. | 08-06-2009 |
| 20090207482 | Optical transmission system using raman amplifier and controlling method thereof - The optical transmission system modulates backward Raman pump light provided to an optical transmission line on one link side of an uplink and downlink, to thereby transmit a pilot signal for confirming a connection state of the optical transmission line to a node on an upstream side. When the pilot signal is received by the node on the upstream side, the backward Raman pump light provided to the optical transmission link on the opposite link side is modulated to thereby send back a response signal to an own node. Then by confirming receipt of the response signal at the own node, the backward Raman pump light provided to the optical transmission line on the one link side is changed over from a low output state to a high output state. | 08-20-2009 |
| 20090213454 | RAMAN AMPLIFICATION APPARATUS AND DISTRIBUTED RAMAN AMPLIFICATION SYSTEM AS WELL AS STARTING UP METHOD FOR DISTRIBUTED RAMAN AMPLIFICATION SYSTEM - A Raman amplification apparatus includes a pumping light supplying section, a main signal wavelength light level acquisition section, a monitoring signal wavelength light level acquisition section, a function information storage section for storing, as function information, information regarding functions for deriving a noise amount and a gain by Raman amplification with regard to a monitoring signal wavelength light with respect to pumping light power supplied from the pumping light supplying section, and a transmission characteristic derivation section for deriving a transmission characteristic on an optical transmission line based on information acquired by the main signal wavelength light level acquisition section and the monitoring signal wavelength light level acquisition section and the function information stored in the function information storage section, and Raman gain is derived with high accuracy in comparison with the conventional technique. | 08-27-2009 |
| 20090219609 | Optical amplifier provided with control function of pumping light, and optical transmission system using the same - In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light. | 09-03-2009 |
| 20090231681 | OPTICAL SYSTEM FOR REDUCING STIMULATED BRILLOUIN SCATTERING BY CONTROLLABLY CHANGING POLARIZATION DIRECTION OF AN OPTICAL SIGNAL - An optical system having an input surface configured to receive an input optical signal having a polarization, and a polarization changer comprising the input surface and configured to generate two orthogonal polarization components from the input optical signal. The polarization changer also changes a direction of the polarization of the input optical signal in a controlled manner while maintaining coherence of the two orthogonal polarization components in order to reduce stimulated Brillion scattering. | 09-17-2009 |
| 20090237778 | Monitoring method and apparatus of noise light due to raman amplification and optical communication system using the same - A monitoring apparatus, based on an optical power monitored in photodetectors arranged at input and output ends of a transmission line, in a condition where pump light is supplied to the transmission line at a time of initial startup of an optical communication system, obtains a relationship for the noise light generated due to Raman amplification, between forward direction noise light power and backward direction noise light power, and while in service, converts the backward direction noise light power monitored by the photodetectors at the input ends of the transmission line into the forward direction noise light power in an arithmetic processing section, in accordance with the relationship obtained at the time of the initial startup. As a result the power of noise light generated due to Raman amplification, can be monitored in real time at high speed. | 09-24-2009 |
| 20090237779 | OPTICAL AMPLIFIER - An optical amplifier includes a light source that outputs light having an intensity corresponding to a supplied driving power; a modulator that modulates the light output from the light source in response to an input modulation signal; a Raman amplifier that performs Raman amplification on the light modulated by the modulator using a highly-nonlinear medium; and a driver that supplies the driving power to drive the light source and inputs the modulation signal to the modulator. The driver starts inputting the modulation signal to the modulation unit before the intensity of the light propagating through the Raman amplifier exceeds an intensity value at which stimulated Brillouin scattering occurs in the Raman amplifier. | 09-24-2009 |
| 20090251768 | Multi-band hybrid SOA-Raman amplifier for CWDM - A multi-band hybrid amplifier is disclosed for use in optical fiber systems. The amplifier uses Raman laser pumps and semiconductor optical amplifiers in series to produce a relatively level gain across the frequency range of interest. Multiple Raman pumps are multiplexed before coupling into the fiber. The Raman amplified optical signal may be demultiplexed and separately amplified by the SOAs before re-multiplexing. Gain profiles of the Raman pumps and the SOAs are selected to compensate for gain tilt and to alleviate the power penalty due to cross-gain modulation in the SOAs. The disclosed hybrid amplifier is especially useful in coarse wavelength division multiplexing (CWDM) systems. | 10-08-2009 |
| 20090279164 | Bi-directional propagation optical signal regenerator and optical signal regenerating method utilizing optical nonlinear effect - An optical nonlinear medium | 11-12-2009 |
| 20090296198 | OPTICAL TRANSMISSION SYSTEM AND OPTICAL AMPLIFICATION METHOD USED IN THE SYSTEM - At an optical transmission system that uses plural light sources for Raman amplification, even when a failure occurred in a pumping light source in one of the light sources for Raman amplification, the signal light output level and its wavelength characteristic are not deteriorated at the final stage, and the number of components in the system is not made to be large and the cost of the system is not made to be high. This optical transmission system is provided. At an optical transmission system using “n” light sources for Raman amplification, a first to “n−1”th light sources for Raman amplification do not provide spare pumping light sources, and an “n”th light source for Raman amplification provides the spare pumping light sources. When a pumping light source in one of the “n” light sources for Raman amplification had a failure, the spare pumping light source in the “n”th light source for Raman amplification corresponding to the failure occurred pumping light source is worked. With this, the signal light output level and its wavelength characteristic are recovered to a normal state before the failure occurred. | 12-03-2009 |
| 20090323173 | LIGHT OUTPUT CONTROL APPARATUS - A light output control apparatus, includes: | 12-31-2009 |
| 20090323174 | METHOD AND ARRANGEMENT FOR THE RAPID ADJUSTMENT OF THE TILT OF OPTICAL WDM SIGNALS - An anti-pump laser (AL) is used in addition to a tilt correction pumplaser (KL) for Raman tilt control, said anti-pump laser injecting an anti-pump signal into a transmission fiber (FI) or a dispersion compensation fiber (DCF). The anti-pump laser (AL) has the function of reducing the pump energy of the control pump laser (KL) in the course of the fiber (FI, DCF), in order to restrict its effective length and to enable a faster adjustment of the tilt. | 12-31-2009 |
| 20100027103 | Zonal Lenslet Array - The invention includes a master lens, which initially focuses a laser pulse, and then the pulse passes through a zonal lenslet array, which uses different lenslet elements that provide for predetermined focal lengths so as to establish a three or two dimensional, predetermined dispersion of foci of the laser pulse. The zonal lenslet array of the present invention may be thought of as a variant of a Shack-Hartman wave front sensor, but used for an entirely different application. | 02-04-2010 |
| 20100067099 | RAMAN AMPLIFIER, OPTICAL REPEATER, AND RAMAN AMPLIFICATION METHOD - A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source. | 03-18-2010 |
| 20100073762 | Raman amplifier and control method thereof - A Raman amplifier, at the time of start up or the like, drives a predetermined number of pump light sources among a plurality of pump light sources, in a stable region, and judges a Raman gain in the transmission line, and based on the judgment result, specifies a pump light source to switch on and a pump light source to switch off, among the plurality of pump light sources, and controls the drive state of the pump light sources that are switched on. As a result, the plurality of pump light sources are appropriately driven corresponding to the system requirements so that stable behavior is possible, and constant control of Raman gain can be realized at a high accuracy. | 03-25-2010 |
| 20100079853 | OPTIMIZED CASCADED RAMAN FIBER-BASED LASER SOURCE FOR HIGH EFFICIENCY MID-INFRARED SPECTRAL GENERATION - A laser structure is provided that includes a pulsed source producing a pulsed signal having a low spontaneous noise component to its spectral output and a pulse-shape that is optimally flat. Also, the laser structure includes one or more optical fiber structures receiving the pulsed signal and performing Raman amplification. The pulsed signal is used to excite in the one or more optical fiber structures possessing normal chromatic dispersion, which acts as a nonlinear system for efficient mid-infrared spectral generation. | 04-01-2010 |
| 20100097689 | OPTICAL AMPLIFIER, FIBER LASER, AND METHOD OF ELIMINATING REFLECTED LIGHT - A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light. | 04-22-2010 |
| 20100134875 | Optical amplifier, and optical transmission system including the optical amplifier - An optical amplifier provided in a repeater station of an optical transmission system is proposed. The optical amplifier amplifies an signal light and performs ALC of output power by means of a variable optical attenuator (VOA). The optical amplifier receives a difference between a target output value and measured output value of an upstream optical amplifier as an expected control volume, and updates a target attenuation value for the VOA in accordance with a current target attenuation value set to the VOA for ALC, a difference between its own target output value and measured output value, and the expected control volume. The target attenuation value is updated at intervals of time exceeding output convergence time by ALC. The difference between the target output value and measured output value of the optical amplifier is adopted as the expected control volume for a downstream optical amplifier. As a result, the waiting time taken for ALC to be stabilized at the time of increment or decrement of the number of wavelengths and signal startup in the optical transmission system where each station performs ALC, can be shortened, and the variation in the level of the signal light power during transition from AGC to ALC is suppressed. | 06-03-2010 |
| 20100157416 | Optical amplifier provided with control function of pumping light, and optical transmission system using the same - In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light. | 06-24-2010 |
| 20100214649 | Optical Fiber Amplifier Having Nanostructures - Disclosed is a stimulated Raman scattering effect (SRS), amplifying optical fiber that includes a central core comprising a dielectric matrix that is capable of vibrating at a given frequency (ω | 08-26-2010 |
| 20100238538 | OPTICAL FIBER AMPLIFIER AND METHODS OF MAKING THE SAME - A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier. | 09-23-2010 |
| 20100284060 | Systems and Methods for Cascaded Raman Lasing at High Power Levels - In a light amplification system, a fiber-based oscillator, amplifier, and cascaded Raman resonator are coupled together in series. The oscillator output is provided as an input into the amplifier, the amplifier output is provided as a pumping input into the cascaded Raman resonator, and the cascaded Raman resonator provides as an output single-mode radiation at a target wavelength. A loss element is connected between the oscillator and amplifier, whereby the oscillator is optically isolated from the amplifier and cascaded Raman resonator. A filter is coupled between the isolator and the amplifier for filtering out backward-propagating Stokes wavelengths generated in the cascaded Raman resonator. The oscillator is operable within a first power level range, and the amplifier and cascaded Raman resonator are operable within a second power level range exceeding the first power level range. | 11-11-2010 |
| 20100284061 | Systems and Techniques for Suppressing Backward Lasing in High-Power Cascaded Raman Fiber Lasers - In a light amplification system and technique, a pump source provides pump power at a source wavelength. The pump power is launched as an input into a cascaded Raman resonator. A wavelength-dependent loss element is connected such that it precedes the cascaded Raman resonator. The wavelength-dependent loss element is configured to transmit light power at the source wavelength with low loss, and to provide high loss at the first Stokes shift. The wavelength-dependent loss element prevents buildup of light power between the pump source and the cascaded Raman resonator, thereby preventing backward propagation of light power back into the pump source. | 11-11-2010 |
| 20100290106 | Cascaded Raman Fiber Laser System Based on Filter Fiber - A light generation and amplification system includes a length of laser-active filter fiber having a refractive index profile that suppresses unwanted Stokes orders at wavelengths longer than a target wavelength and that has normal dispersion over its operating wavelength. A nested series of reflectors is provided at the fiber's input and output ends, and are configured to provide a nested series of Raman cavities, separated in wavelength by approximately the respective Stokes shifts. The first cavity in the series is a combined cavity that provides laser oscillation due to a combination of ionic gain and feedback at a selected first wavelength and that provides Raman gain to light at the first Stokes shift of the first wavelength when light at the first wavelength has an energy exceeding a Raman scattering threshold. The Raman cavities provide a stepwise transition between the first wavelength and the target wavelength. | 11-18-2010 |
| 20100296155 | OPTICAL FIBER RAMAN AMPLIFIER - The invention provides simultaneous suppression of PMD and PDG in a fiber Raman amplifier. One embodiment employs a two-section fiber with one section being unspun and the other, longer, section having a periodic spin profile. The other embodiment employs a single segment fiber having a periodic exponentially varying spin profile. | 11-25-2010 |
| 20100302626 | MOPA LIGHT SOURCE - The present invention relates to a MOPA light source capable of obtaining pulse output by wavelength-conversion of pulse light of fundamental light wave using a simple configuration, and suppressing optical output using a simple method when processing is not performed. The fundamental light wave outputted from a seed light source is amplified in an optical amplification fiber. The amplified fundamental light wave is inputted to one end of a passive optical fiber, and propagates in the passive optical fiber. In the passive optical fiber, stimulated Raman scattering occurs upon propagation of the fundamental light wave. The light of fundamental light wave and light of stimulated Raman-scattered components are outputted from the other end of the passive optical fiber. The light outputted from the passive optical fiber is collimated by a lens, and is then inputted to a branching filter. The light inputted to the branching filter is wavelength-separated into light of stimulated Raman-scattered components having wavelengths longer than that of the fundamental light wave, and light having wavelengths equal to or less than that of the fundamental light wave. | 12-02-2010 |
| 20110013267 | Fiber-Adaptive Distributed Raman Amplifier Pump Setup Scheme - Techniques, in the form of an apparatus, logic and a method, are provided to set power levels for multiple Raman pump wavelengths in a distributed Raman amplification configuration in order to achieve a target gain and tilt or desired gain profile. A Raman pump light source is activated at each of a plurality of pump wavelengths and at each of a plurality of pump power levels such that only one pump wavelength at a given pump power level is active at a time to thereby amplify an optical probe signal in the optical fiber to produce an amplified probe signal. The level of the amplified probe signal at each of the pump power levels for the plurality of pump wavelengths is measured. The pump power level for each of the plurality of pump wavelengths is computed based on the measured levels of the amplified probe signals due to each of the pump power levels and at each of the pump power levels for the plurality of pump wavelengths. | 01-20-2011 |
| 20110019268 | RAMAN AMPLIFIER AND RAMAN AMPLIFIER ADJUSTMENT METHOD - A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value. | 01-27-2011 |
| 20110026104 | RAMAN AMPLIFIER AND RAMAN AMPLIFIER ADJUSTMENT METHOD - A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value. | 02-03-2011 |
| 20110038035 | NARROW BAND FIBER RAMAN OPTICAL AMPLIFIER - Optical Raman fiber amplifier ( | 02-17-2011 |
| 20110080634 | MULTI-STAGE RAMAN AMPLIFIER - A Raman amplifier includes at least a first and a second optical Raman-active fiber disposed in series with each other. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of said first and second group of frequencies extends over a pump frequency range having a width of at least the 40% of the Raman shift. The minimum and the maximum frequency in each of said first and second group of frequencies differ with each other of at most the 70% of said Raman shift. | 04-07-2011 |
| 20110141552 | AUTOMATIC MEASUREMENT AND GAIN CONTROL OF DISTRIBUTED RAMAN AMPLIFIERS - Apparatus and method for gain measurement and control of a Distributed Raman Amplifier (DRA). Various embodiments of the apparatus include a detection unit operative to measure, during operation of the DRA, the optical power of a filtered component of the light entering the DRA from the transmission fiber and a gain calculation and control unit coupled to the detection unit and operative to calculate a signal Raman gain property from the measured optical power. The filtered component may exemplarily be a result of passing the light through a band pass filter, a spectral filter with a given spectral shape or a notch filter. The signal Raman gain property may be an average on-off signal Raman gain, an average net signal Raman gain or a signal Raman gain tilt within a communication band. The apparatus and method may be used to operate the DRA in Automatic Gain Control, i.e. to maintain a required constant signal Raman gain and/or signal Raman gain tilt. | 06-16-2011 |
| 20110141553 | RAMAN AMPLIFIER, OPTICAL REPEATER, AND RAMAN AMPLIFICATION METHOD - A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source. | 06-16-2011 |
| 20110157687 | SYSTEM AND METHOD OF RAMAN AMPLIFIER PUMP CONTROL - An example method includes receiving power measurements for a plurality of optical channels. Deviation measurements representing a difference between respective power measurements and corresponding power targets for the plurality of optical channels are created. Correctable deviations for the plurality of optical channels are determined based on the deviation measurements. The correctable deviations may be determined by projecting the measured deviations into a space that defines Raman gain profiles achievable with a set of channels and pumps. Pump settings for a plurality of pumps are determining based upon the correctable deviations for each channel by solving an optimization problem. The pump setting so determined may be applied to the plurality of pumps. | 06-30-2011 |
| 20110176201 | MODULAR SET OF DEVICES FOR OPTICAL AMPLIFICATION OF SIGNAL BY RAMAN FIBER AMPLIFIER - Modular set is formed by optical module interconnected with control module of electronic system. Optical module is formed by at least two pairs of laser diodes connected in series and including Peltier cooler and thermistor, which are connected to inputs of polarizing fiber combiners, and depolarized outputs of these polarizing fiber combiners are connected to inputs of a wavelengths combiner. Module of the electronic system is formed by a control microprocessor interconnected with direct current power supply source, with PID regulators of laser diodes temperature, a display indicating temperature of individual laser diodes and current flowing through them, and a control panel. To the microprocessor of the module of the electronic system is connected a gate array and to this gate array are connected generators of current impulses, which do not overlap in time, and their widths, repetition frequencies and amplitudes are adjustable, while the number of generators of current impulses equals to the number of pairs of laser diodes and their outputs are connected via power stages to pairs of laser diodes connected in series, and where to the power stages is connected an analogue/digital converter, which is connected also to the microprocessor. | 07-21-2011 |
| 20110235164 | METHOD AND APPARATUS FOR CONTROLLING AN OUTPUT OF AN OPTICAL AMPLIFIER - A system is provided that includes optical amplifiers provided upstream from an optical add-drop multiplexer (OADM). One of the optical amplifiers may be a Raman amplifier that supplies amplified light to another optical amplifier, such as an erbium doped fiber amplifier (EDFA), which, in turn, further amplifies and feeds the light to an input of the OADM. During turn-up, for example, the EDFA may initially be disabled, the power of the pump lasers of the Raman amplifier may be gradually increased until light input to the EDFA exceeds a power threshold at which the EDFA can amplify the input light. Light supplied to the EDFA does not have an excessive amount of power. Accordingly, at this point, the gain of the EDFA may be appropriately adjusted and then activated to supply optical signals to the OADM. Such optical signals may have a low power but not too low so as to prevent proper operation of downstream EDFA. Moreover, these optical signal do not have power that is so high as to cause “spiking.” As a result, cross-talk with optical signals added by the OADM is minimized, and such added optical signals may be sufficiently amplified by optical amplifiers downstream from the OADM. | 09-29-2011 |
| 20110249318 | REGENERATIVE LASER AMPLIFIER - A laser amplifier system is presented including a pump regenerative amplifier. The amplifier generally has a cavity defined by a pair of end cavity mirrors between which an amplified pump pulse oscillates. The amplifier also includes an interaction cell with a tunable gain medium amplifies laser pulses (e.g., Raman gain). The interaction cell may be positioned within the pump amplifier cavity and an input pulse may be injected into the cavity of the amplifier to transit through the tunable gain medium of the interaction cell. A pump pulse transfers energy via interaction with the input pulse (e.g., Raman interaction) as the pulses counter-propagate through the gain medium of the interaction cell. Amplification of output laser pulses, however, is generally achieved according to the wavelength of the pump laser pulses thereby providing a wavelength dependent, or “tunable”, means for amplifying laser pulses. | 10-13-2011 |
| 20110255151 | Optical Network Amplifier Node and Method of Channel Power Depletion Compensation - A method of compensating for channel power depletion induced by Raman amplification noise in a hybrid distributed Raman amplifier-Erbium doped fibre amplifier. In the method, an equivalent noise figure is determined for a virtual amplifier equivalent to the hybrid distributed Raman amplifier-Erbium doped fibre amplifier, and having an input power equal to the input power of the Erbium doped fibre amplifier when the distributed Raman amplifier is off and an output power equal to the Erbium doped fibre amplifier output power. A compensation power, dependent at least in part upon the equivalent noise figure, is determined. A control signal is provided for controlling the hybrid amplifier such that an optical signal amplified by the hybrid amplifier has a total output power equal to a predetermined nominal output power plus the compensation power. | 10-20-2011 |
| 20110279888 | MULTICORE TRANSMISSION AND AMPLIFIER FIBERS AND SCHEMES FOR LAUNCHING PUMP LIGHT TO AMPLIFIER CORES - An optical transmission and amplification system includes a multichannel transmission span with a length of a multicore transmission fiber having a plurality of individual transmission cores. A first tapered multicore coupler provides connectivity between the plurality of transmission cores of the multicore fiber and a respective plurality of individual transmission leads. A fiber amplifier is provided having a plurality of individual cores including at least one pump core and a plurality of amplifier core. A second tapered multicore coupler provides connectivity between the amplifier cores of the fiber amplifier and a respective plurality of amplifier leads, and between the at least one pump core and a respective pump lead. | 11-17-2011 |
| 20110286084 | RAMAN AMPLIFIER - A Raman amplifier includes a semiconductor laser and an optical amplification fiber connected to an optical transmission fiber used for transmitting optical signals. In the Raman amplifier, excitation light emitted from the semiconductor laser is introduced into the optical amplification fiber while excitation light is incident on the optical transmission fiber, thus amplifying optical signals owing to stimulated emission of Raman scattering in both the optical amplification fiber and the optical transmission fiber. The optical amplification fiber is connected to the upstream/downstream side of the optical transmission fiber along the transmitting direction of optical signals, so that excitation light is introduced into the optical amplification fiber inversely toward the downstream/upstream side of the optical transmission fiber along the transmitting direction. The Raman amplifier including a single semiconductor laser can be reduced in manufacturing cost. | 11-24-2011 |
| 20110292496 | LASER SYSTEM WITH HIGHLY LINEAR OUTPUT - A laser device having a semiconductor gain element optically coupled to an optical fiber by using an angled anamorphic fiber lens and including a wavelength-selective front reflector. The laser device possesses improved output characteristics such as a highly linear laser emission output, even when the amplification section produces a high amount of gain. Such a laser source can also be used in various applications such as pump lasers for fiber amplifiers or frequency doubling systems. | 12-01-2011 |
| 20110292497 | APPARATUS AND METHOD FOR CONTROLLING GAIN PROFILE OF AN OPTICAL AMPLIFIER - A change in loading conditions of fiber amplifiers in an optical communications network causes rapid variations in the gain profile of the amplifiers due to spectral hole burning and stimulated Raman scattering. An apparatus for reducing such gain profile variations is described which monitors optical signal perturbations and reacts by adjusting pump powers of the amplifiers and, or fast variable optical attenuator according to a pre-determined function stored in the form of constants in controller's memory. The optical signal is monitored as total power, and the power of light after passing through one or more optical filters. The light detection is relatively fast, whereby the gain profile variations are compensated by fast controlled variable optical attenuator and pump power adjustment upon the change in loading conditions. | 12-01-2011 |
| 20120013975 | OPTICAL AMPLIFIER AND TRANSMISSION LOSS MEASUREMENT METHOD - An optical amplifier that amplifies signal light with Raman amplification in the Raman amplification medium. The optical amplifier includes a light source that supplies pump light into the Raman amplification medium, a first detector that detects input power of the pump light to be input to the Raman amplification medium, a second detector that detects output power of the pump light output from the Raman amplification medium, and a processor operable to calculate transmission loss of the pump light in the Raman amplification medium by comparing the input power with the output power, and calculate transmission loss of the signal light in the Raman amplification medium based on the transmission loss of pump light corrected based on a wavelength of the signal light and a wavelength of the pump light. | 01-19-2012 |
| 20120170111 | OPTICAL AMPLIFIER FOR MULTI-CORE OPTICAL FIBER - One aspect provides an optical device. The optical device includes a first and a second array of optical couplers, a plurality of waveguides and a plurality of pump couplers located over a surface of a substrate. The optical couplers of the first array are able to end-couple in a one-to-one manner to the optical cores of a first multi-core fiber having an end facing and adjacent to the first array and the surface. The optical couplers of the second array are able to end-couple in a one-to-one manner to optical cores having ends facing and adjacent to the second array. The plurality of optical waveguides connects in a one-to-one manner the optical couplers of the first array to the optical couplers of the second array. Each optical waveguide has a pump coupler connected thereto between the ends of the waveguide. | 07-05-2012 |
| 20120218625 | OPTICAL AMPLIFIER CONTROL APPARATUS - An optical amplifier control apparatus according to the present invention includes control circuit | 08-30-2012 |
| 20120224253 | DISTRIBUTED RAMAN AMPLIFICATION APPARATUS, DISTRIBUTED RAMAN AMPLIFICATION METHOD, AND NON-TRANSITORY COMPUTER READABLE MEDIUM STORING DISTRIBUTED RAMAN AMPLIFICATION PROGRAM - A distributed Raman amplification apparatus includes a Raman excitation light source that outputs Raman excitation light to a transmission line fiber through which signal light propagates, a light source control unit that controls an output wavelength of the Raman excitation light source to prevent the Raman excitation light from changing a wavelength spectrum of the signal light, an intensity measurement unit that measures intensity of the Raman excitation light before and after propagation through the transmission line fiber, and a loss calculation unit that calculates a loss of the Raman excitation light in the transmission line fiber based on the intensity of the Raman excitation light before and after propagation through the transmission line fiber measured by the intensity measurement unit. This allows real-time monitoring of the Raman gain. | 09-06-2012 |
| 20120307351 | RAMAN AMPLIFIER AND RAMAN AMPLIFIER ADJUSTMENT METHOD - A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value. | 12-06-2012 |
| 20120327505 | METHOD OF PERFORMING TARGET RAMAN GAIN LOCKING AND RAMAN FIBER AMPLIFIER - An embodiment of the present invention discloses a method of performing target Raman gain locking and a Raman fiber amplifier. The Raman fiber amplifier comprises a coupler ( | 12-27-2012 |
| 20130010351 | METHODS AND SYSTEMS FOR CONVERTING OR AMPLIFYING - A system for conversion or amplification using quasi-phase matched four-wave-mixing includes a first radiation source for providing a pump radiation beam, a second radiation source for providing a signal radiation beam, and a bent structure for receiving the pump radiation beam and the signal radiation beam. The radiation propagation portion of the bent structure is made of a uniform Raman-active or uniform Kerr-nonlinear material and the radiation propagation portion comprises a dimension taking into account the spatial variation of the Raman susceptibility or Kerr susceptibility along the radiation propagation portion as experienced by radiation travelling along the bent structure for obtaining quasi-phase-matched four-wave-mixing in the radiation propagation portion. The dimension thereby is substantially inverse proportional with the linear phase mismatch for four-wave-mixing. The system also includes an outcoupling radiation propagation portion for coupling out an idler radiation beam generated in the bent structure. | 01-10-2013 |
| 20130063808 | Method and Apparatus for Suppression of Stimulated Brillouin Scattering Using Polarization Control with A Birefringent Delay Element - A method and apparatus for suppression of stimulated Brillouin scattering (SBS) includes a master oscillator (MO) that generates a beam; a birefringent element that receives and transmits the beam, wherein the beam is transmitted with a transmission delay between two orthogonal axes; a polarization controller that receives the beam and transmits the beam with a desired polarization; a fiber amplifier that receives the beam, amplifies the beam, and transmits a beam; a compensating birefringent element that receives the beam, approximately removes the transmission delay between the two axes of the beam, and transmits an output beam; and a polarization detector that detects the output beam's polarization and provides feedback to the polarization controller to ensure that the polarization of the output beam is approximately equal to a desired output polarization, so as to reduce SBS. | 03-14-2013 |
| 20130070330 | OPTICAL SYSTEM FOR SIGNAL AMPLIFICATION USING A MULTIMODE FIBER - An optical coupler for coupling optical-pump power into a multimode fiber configured to transport an optical space-division-multiplexed (SDM) signal, the coupling being performed in a manner that enables amplification of the SDM signal in the multimode fiber via a stimulated-emission process or a stimulated Raman-scattering process. The optical coupler can be a part of an optical transmitter configured for co-directional pumping, an optical receiver configured for contra-directional pumping, or a relay station disposed within an optical communication link and configured for either type of pumping. The optical coupler can advantageously be used, e.g., to offset the different degrees of attenuation to which the SDM-signal components corresponding to different guided modes of the multimode fiber are subjected to therein. | 03-21-2013 |
| 20130188243 | ALL-IN-ONE RAMAN FIBER LASER - A low-power “all-in-one” Yb/Raman optical fiber laser system includes a pump input, and a Yb/Raman resonator including a segment of integrated Yb/Raman fiber configured to provide both a ionic gain and Raman gain. A set of input gratings and output gratings define a series of reflector pairs that, together with the integrated Yb/Raman fiber, create a nested series of cavities that provide a stepwise transition from the input wavelength to a selected target output wavelength. | 07-25-2013 |
| 20130242379 | METHOD FOR CONTROLLING SIGNAL GAIN OF A RAMAN AMPLIFIER - A Raman amplifier comprising
| 09-19-2013 |
| 20130265634 | Raman Amplifiers - A pump unit ( | 10-10-2013 |
| 20130286467 | MULTISCALE LIGHT AMPLIFICATION STRUCTURES FOR SURFACE ENHANCED RAMAN SPECTROSCOPY - A method, system and article of manufacture for amplification of light for surface enhanced Raman spectroscopy. The method and system include a source of input light, a grating with grooves therein, a nanoparticle array disposed in the grooves with the nanoparticles and grating having a variety of selectable parameters. The combination of the nanoparticles and selected characteristics, including generating hot spots, and the features of the grating enable enhanced amplification of the input light signal to provide an output Raman signal of greatly increased intensity for Raman spectroscopy. | 10-31-2013 |
| 20130286468 | RAMAN AMPLIFIER, OPTICAL REPEATER, AND RAMAN AMPLIFICATION METHOD - A Raman amplifier using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, to output pumping lights having different central wavelengths, an interval between adjacent central wavelengths greater than 6 nm and smaller than 35 nm. An optical repeater is adapted to compensate loss in an optical fibre transmission line by the Raman amplifier. A Raman amplification method wherein the shorter the central wavelength of the pumping light, the higher light power of the pumping light. In the Raman amplifier, a certain pumping 1 wavelength being a first channel, and second to n-th channels are arranged with an interval of about 1 THz toward a longer wavelength side, pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. | 10-31-2013 |
| 20130314768 | CONTROL CIRCUIT, CONTROL METHOD, AND TRANSMISSION SYSTEM - There is provided a control circuit for a transmission system in which signal light transmitted from a transmission-side apparatus via a transmission path to a reception-side apparatus is subjected to Raman amplification by inputting excitation light from the reception-side apparatus to the transmission path. The control circuit includes a first detection unit configured to detect a change amount of an optical loss of the transmission path caused by a state change of the transmission path, a second detection unit configured to detect a backscattered light amount of the excitation light, and a control unit configured to control an intensity of the excitation light input by the reception-side apparatus to the transmission path on the basis of the change amount of the optical loss detected by the first detection unit and the backscattered light amount detected by the second detection unit. | 11-28-2013 |
| 20130329277 | OPTICAL AMPLIFIER AND OPTICAL AMPLIFIER CONTROL METHOD - An optical amplifier includes: a temperature-adjustment-unit that is provided in a wavelength-fixing-unit that fixes a center-wavelength of an excitation-light-source, and adjusts a temperature of the wavelength-fixing-unit, which causes the center-wavelength of the excitation-light-source to vary; a temperature-measurement-unit that measures the temperature of the wavelength-fixing-unit and a temperature of a gain-equalization-unit that equalizes gains of the signal-light on which the Raman amplification is performed using the excitation-light-source; a shift-amount-obtaining-unit that obtains a shift amount data of the center-wavelength of the excitation-light-source from a first-storage-unit and obtains a shift amount of the center-wavelength of the wavelength-band from a second-storage-unit; and a control unit that obtains a temperature-data of the-wavelength-fixing-unit, which corresponds to a difference between two shift amounts that are obtained by the shift amount obtaining unit, from the first-storage-unit, and controls the temperature of the wavelength-fixing-unit based on the obtained temperature-data. | 12-12-2013 |
| 20130329278 | AMPLIFYING APPARATUS AND CONTROL METHOD - An amplifying-apparatus that raman-amplifies light transmitted through an optical-fiber-transmission-path, includes: an inputting-unit that inputs pump light to the optical-fiber-transmission-path; a path-switching-unit that is capable of switching between a first state in which the light transmitted through the optical-fiber-transmission-path is output to a first path and a second state in which the light transmitted through the optical-fiber-transmission-path is output to a second path; a splitting-unit that splits the light output to the second path by the path-switching-unit and outputs resulting first light and second light; and a control-circuit that stores information based on a result of reception of the light output to the first path by putting the path-switching-unit into the first state and then controls power of the pump light on a basis of the stored information and a result of reception of the first light output by the splitting-unit by putting the path-switching-unit into the second state. | 12-12-2013 |
| 20140022626 | HYBRID OPTICAL AMPLIFIER WITH OPTIMIZED NOISE FIGURE - Methods for optimizing a noise figure of a variable gain hybrid amplifier (HA) which includes a variable gain Raman amplifier with adjustable average gain G | 01-23-2014 |
| 20140036347 | ELLIPSOIDAL RAMAN SIGNAL AMPLIFIER - Raman signal amplification apparatus comprises an ellipsoidal reflector providing a first real focus f | 02-06-2014 |
| 20140043674 | OPTICAL AMPLIFIER, OPTICAL AMPLIFYING SYSTEM, WAVELENGTH CONVERTER, OPTICAL AMPLIFICATION METHOD, AND OPTICAL COMMUNICATION SYSTEM - An optical amplifier includes an optical gain fiber into which signal light and pump light are input and at least one relative phase shifter is inserted. Preferably, the relative phase shifter is inserted so that the relative phase in the lengthwise direction of the optical gain fiber falls within a predetermined range containing 0.5 Π. Preferably, the optical gain fiber is a highly non-linear optical fiber having a non-linearity constant of at least 10/W/km. Preferably, the dispersion of the optical gain fiber is within the range from −1 ps/nm/km to 1 ps/nm/km in an amplification band. Preferably, the absolute value of the dispersion slope of the optical gain fiber at a zero dispersion wavelength is no greater than 0.05 ps/nm | 02-13-2014 |
| 20140071520 | Solid State Illumination Source And Inspection System - An exemplary illumination source for an inspection system includes a pulsed seed laser having a wavelength of approximately 1104 nm and a continuous wave, Raman seed laser having a wavelength of approximately 1160 nm. An optical coupler can combine outputs of the pulsed seed laser and the continuous wave, Raman seed laser. Pre-amplification stages can receive an output of the optical coupler. A power amplifier can receive an output of the pre-amplification stages. A sixth harmonic can be generated using the amplified, combined wavelength. Systems for inspecting a specimen such as a reticle, photomask or wafer can include one of the illumination sources described herein. | 03-13-2014 |
| 20140104679 | RAMAN AMPLIFIER GAIN COMPRESSION SYSTEMS AND METHODS BASED ON SIGNAL POWER MONITORING - Raman amplifier gain compression systems and methods based on signal power monitoring are described which estimate distributed Raman amplifier saturation based on a total power measurement at an output of a distributed Raman amplifier and correct for any changes by adjusting the pump power. Since the power measurement, gain estimation, and the pump control and done locally at the Raman amplifier, the duration of any transients is minimized. The systems and methods quickly detect transients on a fiber link using a power monitor in the Raman amplifier, estimate the change in gain due to change in input power from distributed Raman gain, and perform a feedback loop that corrects pump power to eliminate the change in Raman gain locally. | 04-17-2014 |
| 20140146385 | RAMAN AMPLIFIER - Raman amplifier includes: a pump-light generator configured to supply pump light to a transmission fiber; a measurement circuit configured to measure a relationship between power of the pump light and power of noise output from the transmission fiber with respect to a range from first pump-light power to second pump-light power; a signal detector configured to monitor a supervisory signal in output light of the transmission optical; and a decision unit configured to decide a state of the transmission fiber according to the monitoring result. When the supervisory signal is detected without the pump light, the measurement circuit measures the relationship while increasing the power of the pump light from the first pump-light power. When the supervisory signal is not detected without the pump light, the measurement circuit measures the relationship while decreasing the power of the pump light from the second pump-light power. | 05-29-2014 |
| 20140198376 | OPTICAL SENSING CHIP - The present invention relates to an optical sensing chip, which has various applications and may be used repetitively. The optical sensing chip can qualitatively identify different types of molecules and quantitatively analyze small molecules in minute amounts. Regarding a conventional optical sensing chip, an additional sample of known concentration is required as a reference in signal comparison for quantitative determination. In the disclosure, it is unnecessary to add the additional sample of known concentration, but the optical sensing chip itself provides a fixed optical signal that is not varied along with environmental changes to serve as a reference for quantitative determination. In addition, the optical sensing chip also possesses the ability to concentrate or filter sample in real-time. | 07-17-2014 |
| 20140268308 | TILT CONTROL THROUGH OPTICAL PUMP POWER ADJUSTMENT - The adjustment of tilt in an optical signal path of a repeater. The repeater includes an optical pump that optically powers a rare-Earth doped fiber amplifier, which amplifies the optical signal. The optical signal path also includes Raman gain stage implemented in a previous optical fiber span in the optical signal path, and which contributes tilt with respect to wavelength. Adjusting the Raman gain and/or the rare-Earth doped gain also adjusts the combined tilt contributed by these gain stages. However, the rare-Earth doped gain operates at least partially in the saturated regime, thereby stabilizing the gain at the output of the rare-Earth doped amplifier. Thus tilt control may be employed by adjusting optical pump power with reduced effect on overall gain. | 09-18-2014 |
| 20140285874 | METHOD FOR CONTROLLING SIGNAL GAIN OF A RAMAN AMPLIFIER - A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier. | 09-25-2014 |
| 20140300951 | DIRECTLY DRIVEN SOURCE OF MULTI-GIGAHERTZ, SUB-PICOSECOND OPTICAL PULSES - A robust, compact optical pulse train source is described, with the capability of generating sub-picosecond micro-pulse sequences, which can be periodic as well as non-periodic, and at repetition rates tunable over decades of baseline frequencies, from MHz to multi-GHz regimes. The micro-pulses can be precisely controlled and formatted to be in the range of many ps in duration to as short as several fs in duration. The system output can be comprised of a continuous wave train of optical micro-pulses or can be programmed to provide gated bursts of macro-pulses, with each macro-pulse consisting of a specific number of micro-pulses or a single pulse picked from the higher frequency train at a repetition rate lower than the baseline frequency. These pulses could then be amplified in energy anywhere from the nJ to MJ range. | 10-09-2014 |
| 20140376083 | POLARIZATION REDUCING APPARATUS, LIGHT SOURCE APPARATUS, OPTICAL AMPLIFYING APPARATUS, AND EXCITATION LIGHT SOURCE APPARATUS FOR RAMAN AMPLIFICATION - A polarization reducing apparatus includes a separating unit configured to separate input light into components having polarization directions orthogonal to each other; a winding waveguide of silicon formed on a silicon substrate in a winding manner, the winding waveguide transmitting a first component among the components separated by the separating unit; an optical path configured to have a shorter optical path length than the winding waveguide, the optical path transmitting a second component among the components separated by the separating unit; a combining unit configured to combine the first component and the second component; and an output unit configured to output light consisting of the first component and the second component combined by the combining unit. | 12-25-2014 |
| 20150049379 | OPTICAL AMPLIFIER FOR MULTI-CORE OPTICAL FIBER - An optical device comprising a first optical coupler located over a surface of a substrate such that the optical coupler is able to end-couple to an optical core of a first optical fiber having an end facing and adjacent to the first optical coupler and the surface. The optical device further comprises a second optical coupler located over the surface such that the second optical coupler is able to end-couple to an optical core having an end facing and adjacent to the second optical coupler. The optical device also comprises a pump coupler being configured to couple pump light to an optical path that connects the first optical coupler and the second optical coupler. | 02-19-2015 |
| 20150085350 | Multi-Wavelength Distributed Raman Amplification Set-Up - Techniques are presented herein to set power levels for multiple Raman pump wavelengths in a distributed Raman amplification configuration. A first receive power measurement is obtained at a second node with a controlled optical source at a first node turned on and with a plurality of Raman pump lasers at different wavelengths at the second node turned off. A second receive power measurement is obtained at the second node with the controlled optical source at the first node turned on and the plurality of Raman pump lasers turned on to respective reference power levels to inject optical Raman pump power at a corresponding plurality of wavelengths into the optical fiber span. Based on a target Raman gain and a target Raman gain tilt, respective ratios of a total power are obtained, each ratio to be used for a corresponding one of the plurality of Raman pump lasers. | 03-26-2015 |
| 20150131145 | GENERATION OF NARROW LINE WIDTH HIGH POWER OPTICAL PULSES - Narrow line width, high power pulses of optical radiation may be generated by the combination of stimulated emission and stimulated Raman scattering within a rare earth doped optical fibre ( | 05-14-2015 |
| 20150303646 | OPTICAL POINTING SYSTEM - A method for directing a laser pulsed beam towards a selected area/surface of an object, comprising transmitting from a laser assembly that includes an optical transmitter module a pulsed laser beam having a first pulse duration and illuminating therewith an area/surface of the object, thereby obtaining a reflected pulsed laser beam, the reflected pulsed laser beam including a leading portion reflected from a first reflecting area/surface of the object which is the area of the object that defines the shortest optical path between the optical transmitter module, the object and an optical receiver module; receiving, in a second laser assembly that includes the optical receiver module, the reflected pulsed laser beam and converting it into an amplified phase conjugated pulsed beam of a second pulse duration, and transmitting from the second laser assembly the amplified phase conjugated pulsed beam and illuminating therewith on selected area/surface of the object. | 10-22-2015 |
| 20150311668 | METHOD AND APPARATUS FOR DEPOLARIZING LIGHT - A light source assembly ( | 10-29-2015 |
| 20150364897 | Discrete Raman Amplifier - A discrete Raman amplifier comprises a Raman gain fiber, an input port into the Raman gain fiber for receiving optical signals to be Raman amplified, and an output port out of the Raman gain fiber for emitting Raman-amplified optical signals. A pump light input provides pump light to the Raman gain fiber at a plurality of wavelengths so as to provide Raman amplification over the selected signal wavelength range. Within both the pump light wavelength range and the selected signal wavelength range, the Raman gain fiber has only positive chromatic dispersion, and the Raman gain fiber has a moderate effective area. | 12-17-2015 |
| 20160006206 | SELF-AUTOMATIC GAIN CONTROL DISTRIBUTED RAMAN FIBER AMPLIFIER AND AUTOMATIC GAIN CONTROL METHOD - Disclosed is a self-automatic gain control distributed Raman fiber amplifier, in which a signal is transmitted to a self-AGC monitor and a PD via a pump/signal combiner through a transmission fiber and passes through an RFA control circuit, a self-AGC firmware, and an ASCII communication unit and an Raman pump laser module communicates with the RFA control circuit and transmits the signal to the pump/signal combiner. | 01-07-2016 |
| 20160043527 | Distributed Raman Amplifier Systems - A distributed Raman amplifier system is disclosed. Distributed Raman amplifier systems can include a spool of fiber disposed between a distributed Raman amplifier and local or proximate optical point-loss sources, a carrier hotel for example. The spool of fiber has a fiber of sufficient length to offset aggregated losses, which prevents the distributed Raman amplifier from shutting down while also allowing the distributed Raman amplifier to achieve entitled gain by pumping the fiber in the spool. | 02-11-2016 |
| 20160054519 | OPTICAL TRANSMISSION MEDIUM AND OPTICAL AMPLIFIER - An optical transmission medium includes: a plurality of cores; a first cladding that covers each of the plurality of cores; a second cladding that covers a plurality of first claddings; and a reflection layer that covers the second cladding and has reflection characteristics with respect to a wavelength band of multimode light. | 02-25-2016 |
| 20160064890 | LESSENING VARIATIONS OF SPECTRAL CHARACTERISTIC OF AN OPTICAL DEVICE - Devices and methods for lessening a thermal dependence of gain profile of an optical amplifier are disclosed. An optical beam is split in a plurality of sub-beams with a thermally variable power splitting ratio, e.g. one sub-beam may travel a longer optical path length than another. When the sub-beams are recombined, they interfere with each other, causing the throughput to be wavelength dependent. An amplitude of this wavelength dependence is thermally variable due to the thermally variable power splitting ratio. The thermally variable power splitting ratio and the optical path length difference are selected so as to offset a thermal variation of a spectral gain profile of an optical amplifier. | 03-03-2016 |
| 20160111851 | SLANTED FBG FOR SRS SUPPRESSION - An example apparatus includes an optical fiber including a core and cladding, the core being situated to propagate an optical beam along a propagation axis associated with the core, and at least one fiber Bragg grating (FBG) situated in the core of the optical fiber, the fiber Bragg grating including a plurality of periodically spaced grating portions situated with respect to the propagation axis so that light associated with Raman scattering is directed out of the core so as to reduce the generation of optical gain associated with stimulated Raman scattering (SRS). | 04-21-2016 |
| 20190148902 | INTEGRATED SIGNAL LOSS DETECTION IN RAMAN AMPLIFIED FIBER SPANS OR OTHER FIBER SPANS | 05-16-2019 |
