A passive dual polarization unit and coherent transceiver and/or receiver including one or more passive dual polarization units are provided. An example passive dual polarization unit includes a polarization splitter configured to split an input signal into a TE mode and TM mode signals; TE/TM splitters each designed to split the TE/TM mode signals into first TE/TM signals and second TE/TM signals; a first TE signal polarization rotation component for receiving the first TE signal and providing a third TM signal having the same magnitude and time dependence as the first TE signal; a first TM signal polarization rotation component for receiving the first TM signal and providing a third TE signal having the same magnitude and time dependence as the first TM signal; and TE/TM couplers that couple the second TE/TM signals and the third TE/TM signals to generate output TE/TM signals.

A communications system may include a transmitter node, a receiver node, and an optical communications channel coupling the transmitter node and receiver node. The transmitter node may include a pulse transmitter and a pulse divider downstream therefrom. The receiver node may include a pulse recombiner and a pulse receiver downstream therefrom.

A communications system may include a transmitter node, a receiver node, and an optical communications channel coupling the transmitter node and receiver node. The transmitter node may include a pulse transmitter and a pulse divider downstream therefrom. The receiver node may include a pulse recombiner and a pulse receiver downstream therefrom.

Methods and systems for transmitting a signal. A first signal from a first device operating in spatial multiplexing transmission is concatenated with a second signal from a second device operating without spatial multiplexing transmission to generate a concatenated signal in a non-linearly superpositioned constellation, in which a portion of the constellation corresponding to the first signal is symmetrical about each of the real and imaginary axes. The concatenated signal is processed according to transmission processing of the second device, to generate a processed signal. The processed signal is transmitted.

Embodiments of this application provide a clock phase recovery apparatus and method, and a chip. The clock phase recovery apparatus includes an ADC, a dispersion compensation unit, a digital interpolator, a MIMO equalization unit, and a clock offset phase obtaining unit. The ADC is connected to the dispersion compensation unit, and the dispersion compensation unit is connected to a first input end of the digital interpolator. An output end of the digital interpolator is connected to an input end of the MIMO equalization unit, and an output end of the MIMO equalization unit is connected to an input end of the clock offset phase obtaining unit. The digital interpolator is configured to adjust, based on first offset phase information output by the clock offset phase obtaining unit, a dispersion-compensated signal output by the dispersion compensation unit.

Embodiments of this application provide a clock phase recovery apparatus and method, and a chip. The clock phase recovery apparatus includes an ADC, a dispersion compensation unit, a digital interpolator, a MIMO equalization unit, and a clock offset phase obtaining unit. The ADC is connected to the dispersion compensation unit, and the dispersion compensation unit is connected to a first input end of the digital interpolator. An output end of the digital interpolator is connected to an input end of the MIMO equalization unit, and an output end of the MIMO equalization unit is connected to an input end of the clock offset phase obtaining unit. The digital interpolator is configured to adjust, based on first offset phase information output by the clock offset phase obtaining unit, a dispersion-compensated signal output by the dispersion compensation unit.

A device (10;150;200) is configured to receive an optical signal. The device comprises a dispersion compensator (210a) comprising a plurality of optical dispersion compensator units (220). Each optical dispersion compensator unit comprises a plurality of delay elements (20;40). The dispersion compensator (210a) is configured to selectively activate one or more of the optical dispersion compensator units (220). The dispersion compensator (210a) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit (200).

A device (10;150;200) is configured to receive an optical signal. The device comprises a dispersion compensator (210a) comprising a plurality of optical dispersion compensator units (220). Each optical dispersion compensator unit comprises a plurality of delay elements (20;40). The dispersion compensator (210a) is configured to selectively activate one or more of the optical dispersion compensator units (220). The dispersion compensator (210a) is configured to compensate for dispersion of the optical signal with the activated one or more optical dispersion compensator unit (200).

Systems and methods are provided for receiving an optical signal from an optical fiber, including: coupling via an optical coupler the optical signal from an optical fiber into first and second waveguides, wherein the optical signal comprises TE and TM polarized optical signals and the optical coupler couples the TE polarized optical signal into the first waveguide and the TM polarized optical signal into the second waveguide; equalizing the TE and TM polarized optical signals from the coupler to equalize optical power levels of the TE and TM polarized optical signals; optically combining the equalized TE and TM polarized optical signals; and transmitting the combined optical signal to a photodetector.

Communication of light signals and optical cables can be managed to mitigate error associated with using optical cables to communicate light signals. A communication management component (CMC) can embed respective timing synchronization pulses in respective lights signals having respective wavelengths. The light signals can be typical light signals or can be squeezed and twisted to generate a desired twisted light signal. The light signals can be transmitted via the optical cable to a receiver. A CMC, at the receiver end, can determine error associated with the transmission of the light signals via the optical cable and respective characteristics of the respective light signals, including respective arrival times of the respective timing synchronization pulses and respective light intensity or power levels of the respective light signals. From the respective characteristics, CMC can determine a compensation action to perform mitigate the error with regard to subsequent transmissions of light signals.