110 results about "Cross-phase modulation" patented technology

The polarization direction of a signal is rotated by a polarization controller so as to be orthogonal to the main axis of a polarizer. A control pulse generator generates control pulses from control source with a wavelength which is different from the wavelength of the signal. The signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the signal, during the time period in which the signal and the control pulse coincide, has its polarization direction rotated by cross phase modulation, and is amplified by optical parametric amplification. The signal, during the time period in which the signal and the control pulse coincide, passes through the polarizer.

The method according to the present invention includes the steps of inputting an optical signal having a first wavelength and probe light having a second wavelength different from the first wavelength into a nonlinear optical medium, broadening the spectrum of the probe light through cross phase modulation between the optical signal and the probe light inside the nonlinear optical medium, and extracting a signal component including a modulated component of the optical signal and having a band narrower than the band of the spectrum broadened. According to the present invention it can be possible to provide a method and device which can easily convert the wavelength of signal light into an arbitrary wavelength in performing optical 3R functions.

Decreasing the average transmitted power in an optical fiber communication channel using multilevel amplitude modulation in conjunction with Pulse Position Modulation (PPM). This multilevel PPM method does not entail any tradeoff between decreased power per channel and channel bandwidth, enabling a lower average transmitted power compared to On/Off Keying (OOK) with no reduction in aggregate data rate. Therefore, multilevel PPM can be used in high-speed Dense Wavelength Division Multiplexed (DWDM) systems where the maximum number of channels is traditionally limited by nonlinear effects such as self-phase modulation (SPM), cross-phase modulation (XPM), four-wave mixing (FWM), stimulated Brillouin scattering (SBS), and stimulated Raman scattering (SRS). This modulation technique can enable an increased number of channels in DWDM systems, thereby increasing aggregate data rates within those systems.

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.

Systems and method of compensating for transmission impairment are disclosed. One such method comprises receiving a wavelength-division multiplexed optical signal. The received optical signal has been distorted in the physical domain by an optical transmission channel. The method further comprises propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel. The backward propagation fully compensates for fiber dispersion, self-phase modulation, and cross-phase modulation (XPM) and partially compensates for four-wave mixing (FWM).

The present disclosure provides systems and methods for the compensation of signal distortion in fiber optic communication systems and the like. More specifically, the present disclosure provides an orthogonal polarization detection and broadband pilot (OPDBP) technique for the compensation of nonlinear cross polarization (i.e. nonlinear cross polarization modulation) (XPolM) induced noise and nonlinear nonlinear cross phase modulation (XPM) induced noise in a high data rate polarization multiplexed (PM) multilevel-quadrature amplitude modulated (M-QAM) channel due to neighboring channels. This approach allows for the compensation of both XPolM and XPM simultaneously, providing several dBs of optical reach extension. The approach uses a pilot tone based orthogonal polarization detection scheme with broadband (i.e. a few GHz wide) filtering of the pilot tones.

An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially.

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.

The present invention relates to the all-optical logic AND operation in a SOA (semiconductor optical amplifier)-based Mach-Zehnder interferometer. More particularly, it relates to the technology making feasible ultra high-speed logic operations while maintaining a small size and a low input power by utilizing a cross-phase modulation (XPM) wavelength converter composed of semiconductor optical amplifiers in the form of a Mach-Zehnder interferometer with nonlinear characteristics.

The invention relates to a method of reducing the intensity distortion induced by cross phase modulation in a wavelength division multiplexed optical fiber transmission system comprising a transmission line made up of a plurality of optical fiber segments with repeaters interposed between successive optical fiber segments, the transmission system having N different wavelength channels, where N is an integer greater than unity. In each repeater interconnecting first and second consecutive fiber segments, a time offset is introduced between the channels in such a manner that compared with the inlet of the first optical segment, the (n+1)and the nchannels are offset by taun at the inlet to the second fiber segment, where n is an integer less than or equal to N, where taun is selected to be greater than zero and less than a value that eliminates correlation between the intensity distortion contributions of each fiber segment.

An optical signal (116) is modulated with a transmitted electrical signal comprising an information-bearing component (122) and a pilot tone (120) having a predetermined frequency. Transmission of the signal results in distortion, including nonlinear optical transmission impairments. A method of receiving the signal includes detecting the optical signal to produce a received electrical signal (X) comprising a distorted variant of the transmitted electrical signal. The pilot tone is extracted from the received electrical signal using a filtering operation (308) having a predetermined characteristic, and a compensation signal determined based upon the extracted pilot tone. The compensation signal is applied to the received electrical signal (X) to produce a compensated signal (Y) having reduced distortion. The predetermined characteristic of the filtering operation (308) is represented by one or more parameters having values selected so as to substantially maximise a measure of quality of the compensated signal.

The invention relates to a method for generating a drive source of an ultraviolet optical frequency comb. The method comprises the steps of synchronous control of laser and chirped pulse amplification of optical parameters, wherein ultrashort pulses outputted by a laser with stable carrier phase are divided into two beams; one beam is used as signal light to be amplified for chirped pulse amplification of the optical parameters, and the other beam is used for generating synchronous pumping signals through crossed phase modulation or gain selective amplification; picosecond and nanosecond intense pulse laser is taken as a pumping source for chirped pulse amplification of the optical parameters; and ultrashort and ultra-intense laser output is obtained by utilization of compression of grating pairs at an output end for chirped pulse amplification of the optical parameters. The method has the advantages that the method does not need a complex circuit system, can greatly reduce the requirement on the environment and particularly on temperature and vibration, and can obtain the ultraviolet optical frequency comb which has a wider application scope, relatively high power and high repetition frequency and shorter wavelength.

The invention discloses a method for generating supercontinuum from the communication band to the middle infrared based on a silicon nitride waveguide. The method comprises the steps of step 1, using an ultrashort pulse light source to emit the light which has a frequency of 8-12MHz, and a central wavelength of 1.4-2.2 micrometer, step 2, conducting lens coupling of ultrashort femtosecond pulses which is then infused into a ridge/groove hybrid reverse silicon nitride waveguide with a flat light dispersion, wherein the structure of the silicon nitride waveguide comprises a silica oxide layer arranged on a silicon plate, the grooves containing a single silica ridge is formed on the surface of the silica. The silicon nitride waveguide applies the structure of the ridge/groove hybrid to make the effect area of the light field small, and achieve a big non-linear coefficient of the waveguide. After high peak power femtosecond optical pulses are introduced into the waveguide, non-linear processes of self phase modulation, cross phase modulation, four-wave mixing, soliton frequency shift, dispersive wave generation and the like occur, and finally the supercontinuum from the communication band to the middle infrared is formed.

A crosstalk compensation engine for reducing signal crosstalk effects within a data signal. Demultiplexed data signals corresponding to multiplexed data signals received via a signal transmission medium are processed to significantly reduce one or more signal crosstalk products related to one or more interactions among the multiplexed data signals within the signal transmission medium. Such signal crosstalk products include those resulting from dense wavelength-division mutiplexing of the data signals used to provide the multiplexed data signals, four-wave mixing among the multiplexed data signals within the signal transmission medium, and cross-phase modulation among the multiplexed data signals within the signal transmission medium.

The invention relates to a link damage perception energy efficiency routing method for distinguishing services in an elastic optical network, and belongs to the technical field of optical fiber communications. The method designs a path weight formula based on load balancing for comprehensively considering the link frequency spectrum state and the transmission damage, so as to reduce the nonlineardamage among different channels. Based on the path weight formula, an edge-separated maximum weight path is selected for high-quality services; and an edge-separated shortest energy efficiency path isselected for low-quality services. During spectrum allocation, the spectrum is partitioned according to the ratio of the service rate, and a spectrum allocation mode combining first-time hit and tail-end hit is adopted to reduce the cross-phase modulation between the services of different transmission rates. At the same time, in order to reduce the probability that existing services are blocked since the current transmission service causes damage to the existing services in the network, an optical path reconfiguration mechanism of a physical damage blocking service is designed. The link damage perception energy efficiency routing method for distinguishing the services in the elastic optical network provided by the invention effectively improves the spectrum resource utilization rate and reduces the bandwidth blocking rate and the service transmission energy consumption.

A system for estimating cross-phase modulation (XPM) impairments, wherein the method comprises: determining, according to a pump Jones matrix of a pump channel and a probe Jones matrix of a probe channel of each of fiber spans except for the first fiber span in a fiber transmission system, a polarization mode dispersion (PMD)-induced relative polarization status rotation matrix between channels of the each of fiber spans; and determining, according to the rotation matrix of the each of fiber spans, dispersion of a pump signal of the each of fiber spans, differential delay of the pump signal relative to a probe signal of the each of fiber spans and a gain of the each of fiber spans, polarization crosstalk and phase noise of the XPM impairments in the fiber transmission system. This allows the XPM impairments in the effect of the polarization mode dispersion to be quickly and accurately estimated,