Patent application number | Description | Published |
20100092172 | APPARATUS AND METHOD FOR CROSS-CONNECTING OPTICAL PATH IN WAVELENGTH DIVISION MULTIPLEXING SYSTEM - Provided is an optical network in which a wavelength division multiplexing-based optical transmission scheme is implemented. An apparatus for cross-connecting an optical path includes a path switch including a plurality of input terminals receiving optical signals from other nodes, and a plurality of output terminals sending the optical signals to the other nodes, the path switch switching the path of the optical signal so that the optical signal input via one of the input terminals is output to one of the output terminals; and a wavelength converter converting a wavelength of the optical signal input via the input terminal and outputting the wavelength-converted optical signal to the output terminal according to a switching result of the path switch. Thus, inefficient use of a network resource due to wavelength collision can be prevented, the path can be automatically cross-connected and thus quickly established, path switching and branch combination can be performed irrespective of wavelength, and switching can be performed irrespective of direction. | 04-15-2010 |
20100142964 | OPTICAL TRANSMISSION APPARATUS WITH STABLE OPTICAL SIGNAL OUTPUT - An optical transmission apparatus for high-speed optical signal transmission is provided. The optical transmission apparatus includes an optical modulator which includes first and second modulators of a Mach-Zehnder (MZ) interferometer type which are connected in parallel, and an output stabilizer which controls biases for the first modulator, the second modulator and the optical modulator and stabilizes a final output optical signal of the optical modulator. The optical transmission apparatus can perform a stable optical signal output. | 06-10-2010 |
20100150553 | METHOD AND APPARATUS FOR GENERATING OPTICAL SHORT PULSE FOR QUANTUM CRYPTOGRAPHY COMMUNICATION - A method and apparatus for generating an optical short pulse for quantum cryptography communication is provided. The apparatus is incorporated as a module in an electronic integrated circuit chip, such as a field programmable gate array (FPGA) chip which performs quantum key distribution post-processing and open channel optical signal processing of a quantum cryptography system. The apparatus generates an electrical short pulse and converts the electrical short pulse into an optical short pulse, and it is possible to manufacture a compact apparatus for generating an optical short pulse for quantum cryptography communication. | 06-17-2010 |
20100150560 | APPARATUS AND METHOD FOR TRANSMITTING OPTICAL SIGNALS WITH ENHANCED REFLECTION SENSITIVITY IN WAVELENGTH DIVISION MULTIPLEXING PASSIVE OPTICAL NETWORK (WDM-PON) - Disclosed are an optical transmission apparatus and method in a wavelength division multiplexing passive optical network (WDM-PON). The optical transmission apparatus outputs an optical signal by applying a DC bias current and an RF signal to a laser diode at a threshold current level of the laser diode, thereby broadening an optical spectrum of the laser diode. Accordingly, an optical link becomes less vulnerable to reflection induced noise, which contributes to improve stability and reliability of the optical link. | 06-17-2010 |
20100158522 | SEED LIGHT MODULE BASED ON SINGLE LONGITUDINAL MODE OSCILLATION LIGHT SOURCE - A seed light module based on a single longitudinal mode oscillation light source is provided. The seed light module includes a multi-wavelength signal generation light source unit generating a continuous wave (CW) of different wavelengths, a multiplexer wavelength-division multiplexing the light output from the light source unit, a polarization beam splitter splitting the light of multiple wavelength components output from the multiplexer according to specific polarization components, phase modulators phase-modulating signals of a first polarization component and a second polarization component split by the polarization beam splitter onto a sine wave having a frequency and amplitude, a radio frequency (RF) signal generator generating the sine wave, a RF signal distributor distributing the generated RF signal, amplifiers amplifying the distributed RF signals, and a polarization beam combiner combining the lights phase-modulated by the respective phase modulators and providing the combined light as a seed light output. | 06-24-2010 |
20100158531 | CHANNEL ASSIGNMENT METHOD AND APPARATUS FOR WAVELENGTH-DIVISION-MULTIPLEXED TRANSMISSION SYSTEM - Provided is a channel assignment method in a wavelength-division-multiplexed transmission system. The channel assignment method includes obtaining information about signal modulation schemes from a plurality of optical transmitters, and assigning channels to the respective optical transmitters in consideration of the obtained information about the signal modulation schemes. Accordingly, in transmission of channels of different modulation formats, cross phase modulation is minimized, thereby reducing inter-channel interference. | 06-24-2010 |
20110044688 | REMOTELY OPTICALLY AMPLIFIED PON SYSTEM, OLT, AND RN, AND OPTICAL AMPLIFICATION AND GAIN-CLAMPING METHODS OF PON SYSTEM - A remotely optically amplified passive optical network (PON) system, an optical line terminal, and a remote node, and an optical amplification and gain-clamping methods of the PON system are provided. The PON system generates pump light and transmits the generated pump light to an optical transmission line, amplifies primarily an optical signal by the pump light which pumps the optical transmission line, and amplifies secondarily the optical signal by the transmitted pump light which pumps a gain medium of a remote node while maintaining a gain of the optical signal by applying a gain-clamping method to the remote node. | 02-24-2011 |
20110044691 | APPARATUS AND METHOD FOR DETECTING OPTICAL SIGNALS - Disclosed are an apparatus and method for detecting optical signals. The optical signal detection apparatus includes: a signal receiver to convert a received optical signal into an electrical signal; a threshold decision unit to establish a mathematical model based on the electrical signal and to decide an optimized threshold value based on the mathematical model; and a signal detector to detect the electrical signal based on the optimized threshold value. Hence, since threshold values optimized adaptively according to received signals are used, a bit error rate may be lowered and accordingly detection performance may be improved. | 02-24-2011 |
20120128360 | OPEN OPTICAL ACCESS NETWORK SYSTEM - The present invention relates to an open optical access network system in which one optical access network is open to enable a plurality of service providers and a plurality of subscribers to simultaneously use the optical access network, to thereby improve the efficiency of using the optical access network, wherein each subscriber can be provided with a plurality of different services from the plurality of service providers, thereby enabling the flexible selection of services and the flexible change in services, thus improving the efficiency of using an optical infrastructure. | 05-24-2012 |
20120144214 | OPTICAL NETWORK UNIT, POWER SOURCE EQUIPMENT AND POWER SUPPLY SYSTEM USING THE SAME - An optical network unit is provided that includes a communication detector configured to detect whether a communication is achieved between the ONU and at least one power source equipment (PSE), and a power controller configured to detect whether the PSE is powered and to control electrical power, which is provided from the PSE, based on at least one of the detection result about whether the communication is achieved between the ONU and the PSE and the detection result about the PSE is powered. | 06-07-2012 |
20120148191 | ANGLED PHYSICAL CONTACT RECEPTABLE STUB AND ANGLED PHYSICAL CONTACT TRANSMITTER OPTICAL SUB-ASSEMBLY HAVING THE SAME - An APC receptacle stub and an APC TOSA having the same are provided. The APC receptacle stub includes a first APC stub and a second APC stub. The first APC stub has an optical fiber inserted thereto and is provided with one end section polished in an APC shape. The second APC stub has an optical fiber inserted thereto and is provided with one end section polished in an APC shape and an opposite end section which is coupled to an opposite end section of the first APC stub through rotation adjustment in the same axial direction as an axial direction of the opposite end section of the first APC stub. The APC receptacle stub enables easy optical alignment and is applicable to a light source that is sensitive to reflection. | 06-14-2012 |
20120155873 | POWER SAVING APPARATUS AND METHOD FOR OPTICAL LINE TERMINAL AND OPTICAL NETWORK UNIT - A power saving apparatus for an optical line terminal (OLT) and an optical network unit (ONU) is provided. The power saving apparatus includes a determination unit configured to determine whether a data traffic is generated between the ONU and a customer premises equipment (CPE), and a control unit configured to perform control such that each of the OLT and the ONU are converted to a power saving mode if a result of the determination is that a data traffic is not generated. | 06-21-2012 |
20120155876 | SEED LIGHT MODULE FOR WAVELENGTH DIVISION MULTIPLEXING-PASSIVE OPTICAL NETWORK AND METHOD FOR DRIVING THE SAME - A seed light module for a WDM-PON system is provided. The seed light module includes a reflector configured to reflect a part of seed light that is generated from a light source generator, and an optical attenuator configured to attenuate the intensity of the reflected seed light and provide the attenuated seed light, which corresponds to a signal generated by attenuating the intensity of the reflected seed light, to the light source generator. | 06-21-2012 |
20120163802 | WDM-TDM PON REMOTE TERMINAL AND WDM-TDM PON LINK PROTECTION SYSTEM - A wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) remote terminal (RT) is provided. The wavelength division multiplexing (WDM)-time division multiplexing (TDM) passive optical network (PON) remote terminal (RT), includes: a WDM-TDM converter configured to convert a WDM downstream optical signal that is received from a central office terminal (COT) into a TDM downstream optical signal or to convert a TDM upstream optical signal that is received from an optical network terminal (ONT) into a WDM upstream optical signal; an error detector configured to detect an error; and a controller configured to, in response to an error being detected, transmit the WDM upstream optical signal to the COT via a first standby link or transmit the TDM downstream optical signal to the ONT via a second standby link. | 06-28-2012 |
20120163818 | PASSIVE OPTICAL NETWORK APPARATUS FOR TRANSMITTING OPTICAL SIGNAL - Disclosed herein are a remote node and a telephone station terminal in a passive optical network (PON). The remote node includes an optical circulator that transmits downlink signals input from a downlink optical backbone network to a wavelength distributor and transmits uplink signals input from the wavelength distributor to an uplink optical backbone network different from a downlink optical backbone network; and a wavelength distributor that distributes the downlink signal input from the optical circulator into a plurality of wavelengths to be connected to an optical distribution network and connects the uplink signals input from the optical distribution network to the optical circulator. | 06-28-2012 |
20120163819 | DATA TRANSMISSION APPARATUS AND METHOD FOR USE IN SEPARATE-TYPE BASE STATION - A data transmission apparatus for use in a separate-type base station is provided. The data transmission apparatus includes: a digital unit configured to generate first data that includes transmission method information indicating a selected transmission method and data to be transmitted; a time-division synchronization control unit configured to, in response to the selected transmission method being time-division multiplexing (TDM), generate second data by including synchronization information for transmitting the first data using TDM in the first data; and a wavelength conversion unit configured to convert at least one of the first data and the second data into one or more wavelength optical signals using a predefined wavelength or a predefined group of wavelengths and transmit the wavelength optical signals to one or more radio stations. | 06-28-2012 |
20120163822 | APPARATUS AND METHOD FOR DRIVING WAVELENGTH-INDEPENDENT LIGHT SOURCE - An apparatus for driving a wavelength-independent light source is provided. The apparatus includes a seed light signal generation unit configured to generate seed light signals with one or more wavelengths based on a wavelength identification signal, a wavelength light detection unit configured to detect the wavelength identification signal from the seed light signals, an extraction unit configured to extract wavelength information corresponding to the detected wavelength identification signal and extract a driving condition of a wavelength-independent light source corresponding to the extracted wavelength information, and a driving unit configured to drive the wavelength-independent light source according to the extracted driving condition. | 06-28-2012 |
20120163823 | CONTINUOUS-MODE WAVELENGTH CONVERSION APPARATUS, BURST-MODE WAVELENGTH CONVERSION APPARATUS, REMOTE TERMINATION APPARATUS AND CENTRAL OFFICE TERMINATION APPARATUS - A continuous-mode wavelength converting apparatus, a burst-mode wavelength converting apparatus, a remote termination apparatus and a central office termination apparatus for converting a burst-mode upstream wavelength signal into a continuous-mode upstream wavelength signal, and thereby transmitting the signal to a long distance and increasing link capacity. The continuous-mode wavelength converting apparatus may convert a received burst-mode upstream electric signal into a continuous-mode upstream electric signal by inserting a first frame at the front of the signal as an indicator of a start of the signal, inserting a second frame at the end of the burst-mode upstream electric signal as an indicator of an end of the signal, and inserting an idle signal into at least one remaining region of the burst-mode upstream electric signal. | 06-28-2012 |
20130004165 | AUTOMATIC WAVELENGTH RECOGNITION APPARATUS AND METHOD - Provided are an automatic wavelength recognition apparatus and method. The automatic wavelength recognition apparatus includes: a division unit receiving a single optical signal and dividing the received optical signal into a plurality of optical signals; a plurality of filter units filtering the optical signals and having different and wavelength-dependent pass characteristics; a plurality of detection units detecting the filtered optical signals and measuring intensities of the detected optical signals; at least one comparison unit comparing outputs of any two of the detection units; and a wavelength determination unit receiving an output of the at least one comparison unit and determining a wavelength of the above single optical signal using a pre-stored look-up table. | 01-03-2013 |
20130163629 | USER-SELECTABLE LASER AND OPTICAL TRANSMITTER HAVING THE SAME - Provided are a user-selectable laser and an optical transmitter including the same. The user-selectable laser is an external cavity laser including a semiconductor laser diode for outputting an optical signal, and a wavelength selection filter. The user-selectable laser may allow a user to select a wavelength selection filter which is optically coupled with the semiconductor laser diode and selectively causes oscillation at the wavelength of an optical signal output from the semiconductor laser diode. | 06-27-2013 |
20130223796 | ARRAYED WAVELENGTH GRATING ROUTER (AWGR) FOR WAVELENGTH MULTIPLEXING AND DEMULTIPLEXING - An Arrayed Waveguide Grating Router (AWGR) for wavelength multiplexing and demultiplexing is provided. According to an aspect, by generating phase differences of a plurality of received optical signals through an arrayed wavelength in which a plurality of waveguides having a predetermined length difference with respect to each other are arranged, and then coupling the optical signals with the different phase differences, wavelength multiplexing and wavelength demultiplexing are simultaneously performed using the maximum constructive interference and/or destructive interference effect of optical signals. | 08-29-2013 |
20130294768 | OPTICAL LAYER MONITORING APPARATUS AND METHOD THEREOF - An optical layer monitoring apparatus and method thereof are provided. According to an embodiment of the present invention, an optical layer monitoring apparatus including an optical time domain reflectometer (OTDR) function so as to monitor an optical path of a passive optical network (PON), and a method for improving accuracy of measured monitoring results using the optical layer monitoring apparatus are provided. Therefore, it is possible to enable a user to continuously detect distortion or attenuation along the optical path, and to quickly recover from the distortion or attenuation along the optical path when distortion or attenuation is detected. | 11-07-2013 |
20130302029 | WAVELENGTH TUNING TIME MEASUREMENT APPARATUS AND METHOD FOR MULTI-WAVELENGTH PASSIVE OPTICAL NETWORK - A wavelength tuning time measurement apparatus and method for a multi-wavelength passive optical network (MW PON) are provided. The wavelength tuning time measurement apparatus for measuring a wavelength tuning time of a wavelength-variable light source included in the MW PON system includes an optical filter configured to pass only light of a certain wavelength bandwidth and a photo detector configured to sense light passing through the optical filter. The wavelength tuning time is a time taken from a time when a wavelength change signal is transferred to the wavelength-variable light source, to a time when light starts to be successively sensed by the photo detector. | 11-14-2013 |
20140133502 | WAVELENGTH-TUNABLE OPTICAL TRANSMISSION APPARATUS - A wavelength-tunable optical transmission apparatus including an optical array unit comprising a plurality of light sources whose wavelengths are changed, an optical driving unit configured to receive an electrical signal transmitted from an external circuit, generate the current and input the generated current to the optical array unit, and a control unit configured to control the magnitude of current input to the optical array unit by controlling the optical driving unit. | 05-15-2014 |
20140147118 | APPARATUS FOR TRANSMITTING/RECEIVING VARIABLE-WAVELENGTH OPTICAL SIGNAL - There is provided an optical transceiver apparatus including an optical transmitter configured to transmit light of variable wavelength, an optical receiver configured to receive light generated from an opposite light source, and a controller configured to perform initialization to a wavelength corresponding to when an intensity of light received by the optical receiver is greater than or equal to a reference power, while varying the wavelength of light output by the optical transmitter. | 05-29-2014 |
20140153873 | OPTICAL COUPLING MODULE FOR SILICON PHOTONICS CHIP - An optical coupling module for a silicon photonics chip in which a grating is formed on an optical waveguide, and a material having an intermediate refractive index between refractive indexes of a core and a cladding for side surface optical coupling of the silicon photonics chip is provided. The optical coupling module which is optically coupled with an internal/external optical fiber comprises a core transmitting light, and a cladding covering the core and holding the light in the core through total internal reflection, wherein a grating is formed at one end of the core, and a refractive element is formed between the one end of the core and the cladding, has an intermediate refractive index between the refractive indexes of the core and the cladding, and is optically coupled with the internal/external optical fiber. | 06-05-2014 |
20140153933 | TRANSMITTER OPTICAL SUB-ASSEMBLY - A multi-channel transmitter optical sub-assembly (TOSA) is provided. The multi-channel TOSA includes a stem including a sub-mount, a plurality of light sources mounted on the sub-mount, a common ground pad disposed at the sub-mount and connected to ground electrodes of the light sources in common, a common lead pin installed at the stem, and connected to the common ground pad, and a thermistor mounted on the sub-mount along with the light sources. | 06-05-2014 |
20140161446 | OPTICAL AMPLIFIER (OA)-BASED REACH EXTENDER AND PASSIVE OPTICAL NETWORK SYSTEM INCLUDING THE SAME - The TWDM-PON system includes a service provider equipment configured to comprise a plurality of Optical Line Terminals (OLTs), wherein each OLT provides a service in a TWDM scheme; a subscriber equipment configured to comprise a plurality of an Optical Network Units (ONUs), wherein each of the plurality of ONUs utilizes a service provided from one of the plurality of OLTs using an optical signal of an arbitrary wavelength; an Optical Division Network (ODN) configured to transmit multi-wavelength downstream optical signals and multi-wavelength upstream optical signals; and a Reach Extender (RE) configured to comprise at least one of a downstream optical amplifier and an upstream optical amplifier, wherein the downstream optical amplifier is configured to amplify the multi-wavelength optical signals simultaneously, and the upstream optical amplifier is configured to amplify the multi-wavelength optical signals simultaneously. | 06-12-2014 |
20140161461 | TIME AND WAVELENGTH DIVISION MULTIPLEXING - PASSIVE OPTICAL NETWORK (TWDM-PON) SYSTEM AND COMMUNICATION LINK METHOD THEREOF - A Time Wavelength Division Multiplexing-Passive Optical Network (TWDM-PON) system and a communication link method thereof are provided. The communication link method is a method whereby an Optical Network Unit (ONU) which has established communication link to one Optical Line Terminal (OLT) establishes communication link to a different OLT. The ONU receives a wavelength change instruction to change a wavelength thereof to an operating wavelength assigned to the different OLT, and change the wavelength in response to the wavelength change instruction to synchronize to a downstream signal of the operating signal. In addition, the ONU receives an upstream discovery grant signal from the different OLT, and transmits an acknowledgement message to notify the receipt of the upstream discovery grant signal, so that the ONU establishes communication link to the different OLT. | 06-12-2014 |
20140186035 | OPTICAL NETWORK UNIT HAVING POWER SAVING FUNCTION AND POWER SAVING METHOD THEREOF - An optical network unit (ONU) having a power saving function for reducing power consumption in an optical network and a power saving method thereof are provided. The ONU includes a first signal transmitter-receiver unit configured to transmit and receive a signal to and from an optical line terminal, a second signal transmitter-receiver unit configured to transmit and receive a signal to and from customer premises equipment through multiple communication ports, a signal processing unit configured to control a signal to be transmitted and received through the first signal transmitter-receiver unit and the second signal transmitter-receiver unit, and a processor configured to control powers of the first signal transmitter-receiver unit and the signal processing unit according to whether data traffic is received through the plurality of communication ports. | 07-03-2014 |
20140186042 | OPTICAL RECEIVER HAVING WAVELENGTH RECOGNITION FUNCTION, AND DEVICE AND METHOD FOR RECOGNIZING WAVELENGTHS USING THE SAME - Provided are an optical receiver having a wavelength recognition function, and a device and method for recognizing wavelengths using the same. The optical receiver according to an embodiment of the invention includes a splitter configured to split light intensity of input optical signals, a first receiver configured to photoelectrically convert the optical signals split using the splitter, a filter having different pass band characteristics based on wavelengths of the optical signals split using the splitter, a second receiver configured to photoelectrically convert the optical signals passing through the filter, and a comparator configured to compare the optical signals respectively, photoelectrically converted by the first and second receivers and recognize wavelengths of the input optical signals. | 07-03-2014 |
20140186043 | PASSIVE OPTICAL NETWORK REACH EXTENDER BASED ON WAVELENGTH TUNABLE OPTICAL MODULE AND METHOD THEREOF - Provided are a passive optical network reach extender based on a wavelength tunable optical module and a method thereof. According to an embodiment of the invention, a passive optical network reach extender includes a first optical splitter configured to receive an optical signal from an optical line terminal and split the signal into optical signals having a multiplexed wavelength, a wavelength tunable remote relay configured to receive the optical signals split from the first optical splitter, and select and control an available wavelength for each port, a wavelength multiplexer configured to multiplex a wavelength of the optical signal output from the wavelength tunable remote relay, and a second optical splitter configured to split the optical signal multiplexed by the wavelength multiplexer into a plurality of optical network units. | 07-03-2014 |
20140199074 | ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS-PASSIVE OPTICAL NETWORK COMPRISING OPTICAL NETWORK UNIT AND OPTICAL LINE TERMINAL - An orthogonal frequency division multiple access-passive optical network including a plurality of optical network units each configured to generate orthogonal frequency division multiplexed signals, which are allocated thereto, based on a central frequency for frequency division multiplexing that is allocated in advance, and to use the generated signals in upstream transmission. | 07-17-2014 |
20140219661 | METHOD OF SELECTING WAVELENGTH OF OPTICAL NETWORK UNIT IN PASSIVE OPTICAL NETWORK - Provided is a method of selecting a wavelength of an optical network unit including selecting a pre-loaded default wavelength as an available wavelength candidate or the wavelength that has been changed when a preset wavelength changing condition is satisfied as the available wavelength candidate, acquiring frame synchronization for a downstream signal having the same wavelength as the selected available wavelength candidate, and transmitting a registration request message to an optical line terminal (OLT) from which the downstream signal has been transmitted when the frame synchronization is acquired, assigning the available wavelength candidate to an available wavelength used for communication with the OLT and registering the terminal in the OLT when a registration allowance message is received from the OLT. | 08-07-2014 |
20140233954 | LINK ESTABLISHMENT METHOD FOR MULTI-WAVELENGTH PASSIVE OPTICAL NETWORK SYSTEM - Provided is a method of establishing a link between service provider equipment and subscriber equipment in a multi-wavelength passive optical network system. The method of establishing a link includes acquiring information about a wavelength plan of allocated wavelengths in the MW PON system; transmitting a first signal wavelength initialization request signal on a first upstream wavelength from physical layer to the service provider equipment; waiting for a response from the service provider equipment for a predetermined time interval after transmitting the first signal wavelength initialization request signal; and in response to failing to receive a response to the first signal-wavelength initialization request signal within the predetermined time interval, transmitting a second signal wavelength initialization request signal on a second upstream wavelength to the service provider equipment after the waiting. | 08-21-2014 |
20140292413 | TRANSIMPEDANCE PRE-AMPLIFIER WITH IMPROVED BANDWIDTH - A transimpedance pre-amplifier (TIA) with an improved bandwidth. In the TIA, a feedback circuit is added to a regulated cascode structure to be connected in parallel, so that an input resistance value is reduced and a bandwidth is easily broadened. Alternatively, an inductor is added to the regulated cascode structure, so that an input capacitance is reduced and bandwidth is easily broadened. | 10-02-2014 |
20140294026 | LASER DIODE DRIVING APPARATUS FOR OPTICAL COMMUNICATION - A laser diode driving apparatus for optical communication is provided so as to prepare a low-price and low-power optical transmission and reception apparatus by realizing the high performance laser diode driving apparatus for optical communication with a structure appropriate for a multichannel array that can easily and effectively provide stable bandwidths and high gains of the optical communication laser diode at a transmission end of the optical transmission and reception apparatus. | 10-02-2014 |
20150055956 | PASSIVE OPTICAL NETWORK SYSTEM USING TIME DIVISION MULTIPLEXING - Disclosed is a passive optical network system using a time division multiplexing scheme. According to one exemplary embodiment, the passive optical network system includes a plurality of optical network units (ONUs); an optical line terminal (OLT) to be connected to the plurality of ONUs for communication and to transmit and receive an optical signal to and from the plurality of ONUs using a time division multiplexing (TDM) scheme, wherein each of the plurality of ONUs includes a light source that generates an optical signal with a predetermined intensity even in burst-off state; and an optical filter disposed on a receiving path of an optical receiver of the OLT to filter out an optical noise signal received from an ONU in burst-off state among the plurality of ONUs. | 02-26-2015 |
20150055957 | METHOD OF DETERMINING PHYSICAL LAYER WAVELENGTH OF TUNABLE OPTICAL NETWORK UNIT (ONU) IN TIME AND WAVELENGTH DIVISION MULTIPLEXED PASSIVE OPTICAL NETWORK (TWDM-PON) - A method of determining a physical layer wavelength of a tunable optical network unit (ONU) in a time wavelength division multiplexing-passive optical network (TWDM-PON) is provided. First, a receiving wavelength of a tunable receiver is tuned to a downstream wavelength of one of a plurality of operable channels in a TWDM-PON system. Then, it is checked whether the tunable receiver maintains a state of loss of signal (LOS) for a predetermined period of time or the state of LOS is cleared. In response to a determination that the state of LOS is cleared, the ONU performs subsequent link establishment procedures in the channel, and in response to a determination that the state of LOS is maintained, the receiving wavelength of the tunable receiver is changed to a downstream wavelength of another channel. | 02-26-2015 |