Patent application number | Description | Published |
20080231944 | OPTICAL EQUALIZATION OF MULTI-LEVEL SYMBOL CONSTELLATIONS - A method of optically equalizing a multi-level (amplitude or phase) optical signal through the effect of an optical equalizer wherein the optical equalizer (OEQ) is placed at either a transmission end or a receiver end of the optical communications link and a tap delay characteristic of the OEQ need not be determined by symbol spacing, rather it may advantageously be adjusted to desirably compensate non-linear mapping performed in the modulation process or simultaneous operation on a plurality of wavelength division multiplexed (WDM) channels. | 09-25-2008 |
20090003830 | LOSS OF SIGNAL DETECTION - An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters. | 01-01-2009 |
20150086201 | Data Multiplexing And Mixing Of Optical Signals Across Propagation Modes - An apparatus, e.g. an optical device, includes an optical transmitter and a mixer. The transmitter is configured to transmit a plurality of optical data channels that each include at least one spectral component at a same frequency. The mixer is configured to combine a first data channel with a second data channel. The combining is such that first and second optical channels output by the optical transmitter each include contributions from the first and second data channels at the same frequency. | 03-26-2015 |
Patent application number | Description | Published |
20080285983 | MODULATION SCHEME FOR TEDONS - A system and method for increasing transmission distance and/or transmission data rates using tedons and an encoding scheme to reduce the number of ones in a data signal is described. For example, the method for increasing transmission distance and transmission data rate of a fiber optical communications link using tedons includes the steps of encoding a data signal to be transmitted using an encoding scheme that reduces a number of ones in the data signal, transmitting the encoded data signal over the fiber optical communications link, receiving the encoded data signal and decoding the encoded data signal. | 11-20-2008 |
20090067841 | FIBER AND WIRE COMMUNICATION SYSTEM - This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node. The mux-node may route upstream communication signals received from the mini-fiber nodes as downstream signals to other mini-fiber nodes also connected to the mux-node without head-end interaction. | 03-12-2009 |
20110052196 | Narrow-band DPSK apparatus, system, method - System, apparatus and methods are provided for optical communication which tolerates the tight filtering effects from concatenation of reconfigurable optical add drop multiplexers (ROADMs). An exemplary system includes a receiver configured to receive a Narrow-Band Differential-Phase-Shift-Keyed (NB-DPSK) optical signal. The receiver includes a Delay Line Interferometer (DLI) with a path length difference of less than approximately one bit period and a detector for detecting DLI output to form an electrical signal. The bandwidth of the NB-DPSK optical signal is less than approximately one-half of a first bit rate of a transmitter from which the NB-DPSK optical signal is received. The electrical signal is processed to decode transmitted data. A corresponding transmitter amplifies a first input signal having a first bit rate; and drives a DPSK modulator after amplification to generate the NB-DPSK optical signal, which has a bandwidth less than approximately one-half of the first bit rate. | 03-03-2011 |
20120057863 | FREQUENCY-DEPENDENT I/Q-SIGNAL IMBALANCE CORRECTION FOR COHERENT OPTICAL TRANSCEIVERS - In one embodiment, a coherent optical receiver has a digital signal processor that processes one or more digital I/Q-signal pairs to recover data carried by a modulated optical signal in a manner that mitigates, based on calibration data retrieved from a memory or on appropriate performance measures and feedback mechanisms, the detrimental effects of frequency-dependent imbalances between the I and Q sub-channels of at least one of the I/Q channels of the receiver. In various embodiments, the calibration data can be generated and written into the memory at the fabrication facility or in situ while the receiver is being operated in a calibration mode. Alternatively or in addition, the calibration data can be generated and dynamically adjusted online during normal operation of the receiver. | 03-08-2012 |
20130236175 | Method And Apparatus For Space-Division Multiplexing Systems - A space division multiplexed (SDM) transmission system that includes at least two segments of transmission media in which a spatial assignment of the two segments is different is provided. For example, the SDM transmission may include a first segment of transmission media having a first spatial assignment and a second segment of transmission media having a second spatial assignment, wherein the first spatial assignment differs from the second spatial assignment. An example method obtains an optical signal on a first segment of transmission media having a first spatial assignment and forwards the optical signal on a second segment of transmission media with a different spatial assignment. The transmission media may be a multi-core fiber (MCF), a multi-mode fiber (MMF), a few-mode fiber (FMF), or a ribbon cable comprising nominally uncoupled single-mode fiber (SMF). | 09-12-2013 |