In the examples provided herein, a polarization diversity receiver system includes a loop waveguide, and a two-dimensional grating coupler formed on the loop waveguide to couple light impinging on the grating coupler having a first polarization into the loop waveguide in a first direction, and to couple light having a second polarization orthogonal to the first polarization into the loop waveguide in a second direction. The system also includes a first output waveguide positioned near the loop waveguide in a first coupling region, a first distributed perturbation having a first resonant wavelength in the first coupling region to cause coupling of light at the first resonant wavelength between the loop waveguide and the first output waveguide, and a first photodetector to detect light propagating out of a first end and a second end of the first output waveguide.

In the examples provided herein, a polarization diversity receiver system includes a loop waveguide, and a two-dimensional grating coupler formed on the loop waveguide to couple light impinging on the grating coupler having a first polarization into the loop waveguide in a first direction, and to couple light having a second polarization orthogonal to the first polarization into the loop waveguide in a second direction. The system also includes a first output waveguide positioned near the loop waveguide in a first coupling region, a first distributed perturbation having a first resonant wavelength in the first coupling region to cause coupling of light at the first resonant wavelength between the loop waveguide and the first output waveguide, and a first photodetector to detect light propagating out of a first end and a second end of the first output waveguide.

According to a signal transmitting method, a signal receiving method, and a related device and system, a generated single-wavelength optical carrier may be split into N subcarriers with a same wavelength by using a splitting device, corresponding data modulation and corresponding amplitude spread spectrum modulation are performed on the N subcarriers by using N spreading codes and N low-speed data signals obtained by deserializing a received high-speed data signal, to obtain N spread spectrum modulation signals, and the N spread spectrum modulation signals are combined and output. A multicarrier generation apparatus or the like having a relatively complex structure does not need to be used for optical carrier splitting, and spectrum spreading does not need to be performed in a phase modulation manner in which a plurality of delay units or controllable phase units are required.

An object of the present invention is to provide an optical transmission system capable of controlling a transmission capacity and a signal processing load of a MIMO equalizer, without depending on the number of propagation modes of the optical fiber. The present optical transmission system includes an optical fiber 11 with the number of spatial modes being L (an integer of 2 or greater), an optical multiplexer 13 connected to one end of the optical fiber 11 and configured to input M (a natural number of L or less) signal beams of light to the optical fiber 11 and cause the M input signal beams of light to be propagated for each of the spatial modes of the optical fiber 11, an optical demultiplexer 14 connected to another end of the optical fiber 11 and configured to demultiplex a propagated beam of light propagated through the optical fiber 11 for each of the spatial modes of the optical fiber 11, N (N=L) receivers 15 configured to each receive a demultiplexed beam of light obtained by demultiplexing the propagated beam of light, a signal generation apparatus 17 configured to generate P (an integer of from M to L) combined signals from the N received signals, and a P?M MIMO equalizer 16 configured to receive the P combined signals to output M demodulated signals.

An optical source comprises a first laser arranged to generate a first optical signal having a first state of polarization (SOP) and a first optical frequency; a second laser arranged to generate a second optical signal having a second SOP, substantially orthogonal to the first SOP, and having a second optical frequency, different from the first optical frequency by a preselected frequency difference; a polarisation beam coupler arranged to combine the first optical signal and the second optical signal into a composite optical signal comprising both the first optical signal and the second optical signal having said substantially orthogonal SOPs; and an output arranged to output the composite optical signal.

An optical source comprises a first laser arranged to generate a first optical signal having a first state of polarization (SOP) and a first optical frequency; a second laser arranged to generate a second optical signal having a second SOP, substantially orthogonal to the first SOP, and having a second optical frequency, different from the first optical frequency by a preselected frequency difference; a polarisation beam coupler arranged to combine the first optical signal and the second optical signal into a composite optical signal comprising both the first optical signal and the second optical signal having said substantially orthogonal SOPs; and an output arranged to output the composite optical signal.

Systems and methods include a transmitter configured to communicate over an optical link to a receiver; and a controller configured to, with the transmitter and the receiver operating in a first operating mode, obtain measurements related to operation over the optical link, determine statistical properties of the optical link based on the measurements, wherein the statistical properties relate to conditions on the optical link, and set a second operating mode of one or more of the transmitter and the receiver based on the determined statistical properties. Each of the first operating mode and the second operating mode refer to associated settings in one or more of the transmitter and the receiver, and there is a trade-off between the first operating mode and the second operating mode and associated margin on the optical link.

A signal processing circuit includes: a processor configured to adjust phases of reception samples which is supplied at a supply interval, according to a phase adjustment amount; and a processing circuit including a finite impulse response (FIR) filter with taps and configured to process, by the FIR filter, each of the reception samples and output output symbols at an output interval different from the supply interval, the processor is configured to: derive initial values of tap coefficients for the respective taps; and derive the phase adjustment amount such that a center of centroids of the tap coefficients at respective output time points of the output symbols coincides with a center of a number of taps of the FIR filter, the tap coefficients at respective output time points of the output symbols being set according to a deviation between the supply interval and the output interval and the initial values.

Aspects of the present disclosure describe fiber nonlinearity induced transmission penalties are reduced both in fibers with large polarization-mode dispersion, and in coupled-core multicore fibers (CC-MCF). In the case of coupled multi-core fibers, the requirement for modal delay is less.

Aspects of the present disclosure describe fiber nonlinearity induced transmission penalties are reduced both in fibers with large polarization-mode dispersion, and in coupled-core multicore fibers (CC-MCF). In the case of coupled multi-core fibers, the requirement for modal delay is less.