摘要:
Methods and systems for decoding symbols transmitted over an optical channel having a cross-polarization modulation (XPolM) impairment, wherein an optical signal is polarized to encode the symbols on an x-polarization and an y-polarization before transmitted. The method including receiving the optical signal transmitted over the optical channel. Sampling the optical signal to produce a sequence of digital samples, wherein each digital sample includes a measurement of each polarization of the optical signal at an instance of time. Selecting a subset of the sequence of digital samples that includes a digital sample and neighboring digital samples on the sequence. Repeating the selecting and the determining for each digital sample remaining in the sequence of digital samples to produce a sequence of cross-talk coefficients; and decoding some of the symbols from the sequence of digital samples using cross-talk models with corresponding cross-talk coefficients, wherein method steps are performed using a processor.
摘要:
Systems and methods are disclosed for data communication by performing RF sub-band multiplexing and demultiplexing by cascading a radio-frequency (RF) mixing module and optical dual-polarized (DP) QPSK modulator forhybrid RF/optical IQ modulation; and performing intra-transceiver optical superchannel switching through the RF sub-band multiplexing.
摘要:
A polarization demultiplexing optical communication receiver is provided with a signal quality change imparting means which imparts a signal quality change to multiplexed two optical signals; and a signal quality monitoring means which compares signal qualities of the two optical signals with each other after the multiplexed two optical signals imparted with the signal quality change are subjected to polarization separation so as to specify the two optical signals based on a result of the comparison. This makes it possible to reduce transmission characteristics degradation of a polarization-multiplexed optical signal, and to implement transmission having high reliability.
摘要:
A blind equalization technique of high-order QAM signals is provided. A method implemented at a receiver-side in an optical communication network receives an optical signal and performs a two-step polarization tracking process on the received optical signal. Using another method, a polarization multiplexed optical transmission is received by a receiver and a polarization tracking process is performed by applying two different algorithms in parallel. One algorithm may be a decision directed least means square (DD-LMS) algorithm. Another algorithm may be a constant modulus algorithm (CMA).
摘要:
The invention relates to an optical spectrum inverter, configured for counteracting phase distortion effects in an optical channel over a predefined frequency range, to an inverter node, configured for duplex operation in at least two wavelength channels, and to a method for counteracting phase distortion effects in an optical channel. The optical spectrum inverter comprises an optical receiver comprising a polarization diversity unit configured for polarization resolved detection, wherein the optical receiver is configured for receiving an optical input signal comprising a first wavelength span and for converting the optical input signal to an electrical signal, and an optical modulator connectable to the optical receiver and configured for modulating the electrical signal onto an optical signal, wherein the optical modulator comprises an optical filter which is configured for selecting a second wavelength span of the optical signal corresponding to an optical output side band of an inverted spectrum of the optical channel such that phase distortion effects are counteracted at least partly over the predefined frequency range. In this way, an optical spectrum inverter is provided which is simple and cost-effective to realize and allows higher optical power levels in conjunction with a higher capacity per optical channel and is also adapted for longer transmission distances.
摘要:
An optical receiver having a plurality of optical IQ modulators arranged in a butterfly configuration and configured to operate as an optical polarization de-multiplexer. The optical receiver further has (i) an opto-electric circuit configured to apply optical homodyne detection to an optical input signal received by the optical receiver and (ii) a controller configured to generate one or more control signals for driving the IQ modulators of the plurality based on one or more electrical feedback signals received from the opto-electric circuit.
摘要:
In order to reduce influence of noise due to a phase deviation, and to estimate an amount of phase compensation with superior accuracy in a polarization multiplexing/demultiplexing optical communication system, a signal processing circuit includes: optical frequency deviation estimating unit for estimating a frequency deviation which is a difference between a frequency of local light and a frequency of the optical carrier wave which is included in a signal data which corresponds to the polarizations and are generated by mixing a plurality of the optical carrier waves with the local light, which optical carrier wave is phase-modulated and have polarizations able to be demultiplexed and for outputting the estimated frequency deviation as an estimated value; for outputting the estimated frequency deviation as an estimated value; optical frequency deviation compensation amount analyzing unit for calculating an amount of frequency compensation which is an amount of compensation to make a phase of the signal data rotated so as to reduce the frequency deviation, on the basis of a plurality of the estimated values estimated per the signal data; optical frequency deviation compensating unit for making the phase of the signal data rotated correspondingly to the amount of the frequency compensation; optical phase deviation estimating unit for estimating a phase deviation included in each of input signal data and is a difference between a phase of the optical carrier wave and a phase of the local light; and optical phase deviation compensating unit for making the phase of the signal data rotated correspondingly to the phase deviation.
摘要:
A polarization demultiplexing optical communication receiver is provided with a signal quality change imparting means which imparts a signal quality change to multiplexed two optical signals; and a signal quality monitoring means which compares signal qualities of the two optical signals with each other after the multiplexed two optical signals imparted with the signal quality change are subjected to polarization separation so as to specify the two optical signals based on a result of the comparison. This makes it possible to reduce transmission characteristics degradation of a polarization-multiplexed optical signal, and to implement transmission having high reliability.
摘要:
Methods, systems, and devices are described for formatting of data streams to be transmitted over fiber optic channels, and for processing received optical signals. A data transmission device may include a digital coding and modulation module that encodes a digital data stream, inserts unique words into the digital data stream, and modulates the encoded data stream and unique words onto optical channels for transmission over an optical fiber. A demodulation and decoding device may include a unique word identification module that identifies the unique words inserted in each optical channel stream, determines one or more characteristics of the plurality of optical channels based on the unique words, and provides the one or more characteristics to one or more other modules in the demodulator and decoding device.
摘要:
This disclosure describes techniques to sample electrical data streams in coherent receivers. For instance, an analog-to-digital converter (ADC) samples the received electrical data stream at a sampling rate that is nominally twice or greater than twice the symbol rate of the electrical data stream that the ADC receives. A digital filter receives the digital data stream from the ADC, and digitally filters the digital data streams to output a filtered digital electrical data stream at an effective sampling rate that is less than the sampling rate and less than twice the symbol rate, and greater than or equal to the symbol rate.