9 results about "Wdm transmission" patented technology

There is herein described a method of wavelength division multiplexed (WDM) transmission from a first optical terminal to a second optical terminal, the first optical terminal being communicatively connected to the second optical terminal by a free-space optical link, the method comprising at the second optical terminal, receiving a correction signal transmitted by the first optical terminal over the free space link, generating a slave optical frequency comb using a noise-correction factor that has been determined using the correction signal, receiving one or more component frequencies of a master optical frequency comb from the first optical terminal over the free-space optical link using WDM, the one or more component frequencies of the master optical frequency comb having been modulated with first transmission data, extracting the transmission data from the received one or more component frequencies of the master optical frequency comb using the slave optical frequency comb.

The invention provides an optical fiber channel waveform level modeling method and system based on a low-complexity Transform. The method comprises the following steps: building a coherent optical wavelength division multiplexing transmission simulation system; generating and collecting input and output signal data under different optical fiber cross-section conditions; preprocessing the original data set to realize dispersion separation; constructing data sets A and B for two-stage training; a low-complexity Transform model including sliding window attention, rotation position coding, a feedforward neural network and a residual connection module is established; training the model; and modeling the optical fiber channel by using the trained model. According to the method, the problems of high calculation complexity and limited modeling capability of the existing Transform in optical fiber channel modeling are solved.

The application discloses a filter based on a multi-mode subwavelength grating. The filter comprises a mode demultiplexer for multiplexing and demultiplexing of a base mode and a high-order mode, a subwavelength grating for weakly binding regulation of a mode field of the base mode and the high-order mode, and a straight-through waveguide for output of the base mode. The application introduces a structure of the subwavelength grating and weakly binding regulation of the mode field, and by virtue of excellent flat dispersion regulation characteristics, the application realizes apodization of the grating while keeping consistent local refractive index of the grating, thereby obtaining the filter with high side mode suppression ratio and no free spectral range limitation, and the filter can realize flat and low-loss spectral response, meets the next-generation large-capacity and high-speed wavelength division multiplexing transmission demand, and has the advantages of simple structure, simple process, excellent performance and the like.

In a parallel optical communication system technology, there has been a problem that group delay times are generally different between wavelength channels and between spatial channels and that reception times of an optical clock signal and an optical main signal are misaligned.　An optical communication system 301 according to the present invention performs wavelength multiplexing and transmission of an optical main signal Lsig and an optical sub-signal (clock signal) Lclk to an optical transmission line 50. The optical communication system is characterized in that the optical main signal Lsig and the optical sub-signal Lclk are respectively assigned to a wavelength in a normal dispersion wavelength region and a wavelength in an abnormal dispersion wavelength region of the optical transmission line 50.

There is herein described a method of wavelength division multiplexed (WDM) transmission from a first optical terminal to a second optical terminal, the first optical terminal being communicatively connected to the second optical terminal by a free-space optical link, the method comprising, at the first optical terminal, receiving a correction signal from the second optical terminal over the free space optical link, transmitting one or more component frequencies of an optical frequency comb to the second optical terminal over the free space optical link using WDM, the one or more component frequencies of the optical frequency comb having been modulated with transmission data, where the optical frequency comb has been modified using a noise-correction factor derived from the correction signal

This method includes optimizing, by a gradient descent method, a first parameter used in back propagation processing and associated with XPM and a second parameter used in the back propagation processing and associated with SPM and XPM, wherein the back propagation processing is processing to estimate a waveform at a time of transmission by alternately calculating linear terms and nonlinear terms in a nonlinear Schrödinger equation after receiving an optical signal whose waveform shape changed in a transmission line and digitizing a waveform of the received optical signal, and correct, for each channel of plural channels in the transmission line at a time of wavelength-division multiplexing transmission, waveform distortion caused by SPM that occurs in the channel and waveform distortion caused by XPM that occurs in relation with channels other than the channel; and executing the back propagation processing by using the optimized first and second parameters.

The present invention relates to a method for dual-polarisation WDM transmission over optical fibre. The transmission method uses specific I / Q coding for combating the effects of PDL. The modulation symbols to be transmitted on the 2N polarisation states of the N wavelengths are broken down into real values and imaginary values (220). A first orthogonal linear transformation (230-1) is applied to the vector of the real values thus obtained and a second orthogonal linear transformation (230-2), separate from the first, is applied to the vector of the imaginary values thus obtained. A complex scalar solving an irreducible polynome of [X] in is multiplied with the first or second transformed vector before the two transformed vectors are summed (240) in order to provide a vector of transmission symbols for modulating the different states of polarisation of the WDM channels.

Provided is a network node for a coherent optical wavelength division multiplex (WDM) transmission network including at least one remote port which is adapted to receive from and / or output to neighboring network nodes an optical WDM signal including one or more optical channel signals each lying within an optical channel of an optical WDM transmission band and a predetermined number N of local ports, each local port being adapted to receive from a dedicated coherent optical transmitter an optical add channel signal which is to be integrated in an optical WDM signal that is output at a remote port and / or each local port being adapted to output to a respective dedicated optical receiver an optical drop channel signal. The network node includes an optical router device that defines the at least one remote port and further defines an internal remote port, the optical router device being configured to route one or more selected or all optical channel signals included in the optical WDM signal received at a selected remote port as optical drop channel signals to the internal remote port and / or to route one or more optical add channel signals received at the internal remote port to one or more selected remote ports or to all remote ports. The network node further includes a passive optical filter device which is connected, at an internal remote port of the passive optical filter device, to the internal remote port of the optical router device, and which further defines the predetermined number N of local ports. The passive optical filter device is configured to define N optical bandpass filter functions each of which describes a bandpass filter characteristic between the internal remote port of the passive optical filter device and a selected, respectively differing local port. The passband of each optical bandpass filter function covers two or more neighboring optical channels. The passbands of all optical bandpass filter functions differ from each other with respect to the optical channels covered.

This invention provides a link power control method and system for a coherent optical wavelength division multiplexing (WDM) transmission system, comprising: building a coherent optical WDM transmission simulation system; configuring the transmit power of each channel in the WDM system; using the initial state of the transmit power as input to an execution neural network to obtain adjustment values ​​for the transmit power of different channels, and calculating the channel transmit power using the initial state and the transmit power adjustment values; configuring the attenuation of each channel of the wavelength selection switch in the WDM system; using the initial state of the wavelength selection switch as input to an execution neural network to obtain adjustment values ​​for the attenuation of the wavelength selection switch, and calculating the channel transmit power using the initial state and the attenuation adjustment values. This invention is based on a deep reinforcement learning algorithm, and by adjusting the transmit power of different channels in the coherent optical WDM system and the attenuation of different channels in the wavelength selection switch, it achieves optimized power configuration in the link, thereby optimizing the communication quality of each channel at the receiving end after transmission.