Patent application number | Description | Published |
20120148207 | Waveguides Configured To Simultaneously Guide Electromagnetic Waves Of Different Wavelengths - In one embodiment, an waveguide includes a primary core configured to guide electromagnetic waves having relatively long wavelengths, a unit cell having a core configured to guide electromagnetic waves having relatively short wavelengths, the relatively long wavelengths being at least twice as long as the relatively short wavelengths, and a cladding material that surrounds the primary core and the unit cell. | 06-14-2012 |
20120216093 | SOFT-DECISION NON-BINARY LDPC CODING FOR ULTRA-LONG-HAUL OPTICAL TRANSOCEANIC TRANSMISSIONS - Methods and systems for soft-decision non-binary low-density parity-check (LDPC) coding for ultra-long-haul optical transoceanic transmissions are provided. A receiver includes one or more maximum a posteriori (MAP) equalizers configured to decode one or more symbols of an encoded input stream to provide one or more symbol log-likelihood ratios (LLRs). One or more LLR estimators are configured to estimate the log-likelihood ratios of the one or more symbol LLRs to provide one or more bit LLRs. One or more non-binary LDPC decoders are configured to decode the input stream using the one or more bit LLRs to recover an original input stream. | 08-23-2012 |
20120251028 | Polarization-Alternating Optical Signal Generation using CSRZ Modulation - A method for optical chirp-free optical polarization modulation includes dividing a data modulated optical signal into a first optical path and a second optical path, using a Mach-Zehnder intensity modulator in the first optical path for imparting a π phase difference between adjacent symbols of the data modulated optical signal in the first optical path, adjusting a delay and amplitude of symbols of the data modulated optical signal in the second path so that the symbols in the first path and the symbols in the second path are synchronized and have substantially equal power levels, and combining the first and second optical paths so that symbols from the first and second optical paths are in orthogonal polarizations. | 10-04-2012 |
20120263468 | Generation of Optical Quadrature Duobinary Format Using Optical Delay - An optical method for generating an optical quadrature duobinary QDB signal includes receiving a quadrature phase-shift-keying QPSK signal, and adding a delay to the received quadrature phase-shift-keying QPSK signal to generate an optical quadrature duobinary signal. | 10-18-2012 |
20120301146 | Equivalent-Link Backward Propagation Method for Nonlinearity Compensation in Fiber Transmission Systems - A method includes transmitting an optical signal over an optic link in a communication system, the optical link including an optical fiber and optical amplifier; coupling a coherent receiver in the communication system to the optic link for receiving the optical signal; and processing an output from the coherent receiver with digital signal processing DSP in the communication system, the DSP compensating for impairments of the optical signal due to the fiber optic link with an equivalent-link back-propagation. | 11-29-2012 |
20120321303 | Multiple-Symbol Polarization Switching for Differential-Detection Modulation Formats - An inventive method for multi-symbol polarization switching for differential detection optical systems includes modulating a laser source by a DQPSK modulator, driving the DQPSK modulator with a data block configured for generating multi-symbol polarization-switched DQPSK differential-encoded signals, and polarizing the multi-symbol polarization-switched DQPSK signals with a polarizing modulator whose modulation speed is based on how often polarization states vary, wherein the data block provides a bits manipulation to provide the multi-symbol polarization switching thereby enabling differential detection for recovering correct original data by a receiver. | 12-20-2012 |
20120321311 | Coherent Interleaved Polarization-Multiplexing Optical Communications with Single IQ Modulator - An inventive method for coherent interleaved polarization-multiplexing PolMux optical communications with a single IQ modulator includes modulating a light source to generate a 50% return-to-zero RZ signal pulse at a frequency Rs, driving a single IQ modulator with inphase I and quadrature phase Q data at a bit rate of sais Rs to introduce phase modulation on said 50% RZ signal pulse to produce a QPSK pulse signal with all symbols being in a same polarization state without any time overlapping; and polarization modulating said QPSK signal to alternatively convert said QPSK signal into two orthogonal polarizations states enabling an interleaving PolMux signal with a symbol rate of Rs/2. | 12-20-2012 |
20130089327 | Polarization Switching for Optical Fiber Communications - A method implemented in a transmission apparatus used in an optical fiber communications system for a polarization switched differential quaternary phase-shift keying (DQPSK) signal is disclosed. The method comprises splitting data into two or more data streams, inputting said two or more data streams to 1-bit DQPSK precoders to perform 1-bit DQPSK precoding, and multiplexing inphase outputs of the 1-bit DQPSK precoders to generate a first output; and multiplexing quadrature outputs of the 1-bit DQPSK precoders to generate a second output. Other methods, apparatuses, and systems also are disclosed. | 04-11-2013 |
20130094851 | Optical Spectral Shaping for Nonlinearity Enhancement in High Speed Digital Coherent Optical Transmissions - A method includes evaluating an optical signal spectrum for estimated filtering parameters of an optical spectral filtering device for shaping optical signal spectrum, determining a feedback for fine tuning the optical spectral filtering device for nonlinearity tolerance enhancement in the optical transmission system, responsive to received optical signal quality in the optical signal spectrum; and using the feedback to adjust said optical spectral filtering device for predetermined shaping and predetermined fiber nonlinearity tolerance in the optical transmission system. | 04-18-2013 |
20130209035 | OPTICAL DISPERSION COMPENSATION MODULE USING FIBER BRAGG GRATING WITH MULTIPLE DEGREES OF FREEDOM FOR THE OPTICAL FIELD - Systems and methods are disclosed for enhancing optical communication by performing dispersion compensation in an optical fiber using a fiber Bragg grating (FBG); and providing increased degrees of freedoms (DOFs) to distinguish forward and backward propagating fields with a passive component. | 08-15-2013 |
20140099128 | Inter-band cross-phase modulation compensation for the mitigation of intra-channel nonlinear impairments in optical fiber transmission - An optical communication system includes a digital signal processer coupled to the coherent receiver, said coherent receiver including a nonlinearity compensation module for compensating for nonlinear effects in fiber in the optical link for increasing capacity or transmission distance of the fiber, the nonlinearity compensation module includes a spectral slicing of the signal into bands, computing nonlinear interaction between the bands with parameters opposite to those of the fiber to reverse the non-linear effects in the fiber, and only certain nonlinear interactions between bands are considered thereby reducing complexity of the nonlinearity compensation. | 04-10-2014 |
20140178071 | GENERATION OF POLARIZATION-ALTERNATED QPSK FORMAT - Methods, structures and systems for generating different polarization multiplexed signals wherein the drivers of the modulators are generic while a software-controlled manager allows the carrying of any standard 10 G/40 G/100 G data while—at the same time—being adaptively adjustable according to specific link requirements and users' requests in both dispersion-managed and uncompensated links. | 06-26-2014 |
20140310580 | Cyclic Decoding for Cascaded Forward Error-Correction FEC Codes - A computer implemented method for a cyclic (forward-backward) decoding for a forward error-correction FEC scheme includes decoding a given k−1 | 10-16-2014 |
20140314411 | OPTICAL NYQUIST SUPERCHANNEL GENERATION USING MICROWAVE LOW-PASS FILTERING AND OPTICAL EQUALIZATION - Disclosed are structures and methods for generating a Nyquist superchannel. | 10-23-2014 |
20150026541 | Iterative Decoding for Cascaded LDPC and TCM Coding - At a receiver side, to enhance the performance of concatenated LDPC and TCM coding, an iterative decoding between TCM decoder and LDPC decoder enables improvement in the reliability of received LLRs of each symbol after each iteration. A SOVA output of the TCM is used for LDPC decoding, and then the updated LLRs from LDPC decoder are further looped back to the TCM decoder for the next iteration. In such a manner, the decoding performance could be significantly improved after just several iterations. | 01-22-2015 |
20150043680 | Rhombic-QPSK Modulation for Improved Tolerance to Nonlinearity in Fiber Communication Systems - This invention proposes an alternative modulation format for channels that present improved performance when such channels co-propagate with existing intensity modulated channels. This modulation format is named Rhombic-QPSK (R-QPSK) and it is designed in such a way that it presents more tolerance to phase noise created by the nonlinear interaction with the legacy channels. | 02-12-2015 |