In an example, a communication module includes an optical transmitter, an optical receiver, and a periodical filter. The optical transmitter is configured to emit an outbound optical signal. The optical receiver is configured to receive an inbound optical signal. A first frequency of the outbound optical signal is offset from a second frequency of the inbound optical signal by an amount less than a channel spacing of a multiplexer/demultiplexer implemented in an optical communication system that includes the communication module. The periodical filter is positioned in optical paths of both the outbound optical signal and the inbound optical signal and has a transmission spectrum with periodic transmission peaks and troughs. The first frequency of the outbound optical signal may be aligned to one of the transmission peaks and the second frequency of the inbound optical signal may be aligned to one of the transmission troughs, or vice versa.

Provided is an optical transceiver including: a receiver configured to receive an optical transmission signal including wavelength information from another optical transceiver through a multiplexer/demultiplexer connected to the receiver; and a controller configured to identify a reception wavelength for communication with the other optical transceiver and to determine a wavelength corresponding to the reception wavelength as a transmission wavelength for communication with the other optical transceiver, based on the wavelength information included in the optical transmission signal.

A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the optical ports thereof. In an example embodiment, the supervisory optical circuit provides one or more pathways therethrough for supervisory optical signals, each of these pathways having located therein a respective narrow band-pass optical filter. The supervisory optical circuit further provides one or more pathways therethrough configured to bypass the corresponding narrow band-pass optical filters in a manner that enables backscattered light of any wavelength to cross into the optical path that has therein the unidirectional optical amplifier directionally aligned with the propagation direction of the backscattered light.

A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Provided is an optical transceiver including: a receiver configured to receive an optical transmission signal including wavelength information from another optical transceiver through a multiplexer/demultiplexer connected to the receiver; and a controller configured to identify a reception wavelength for communication with the other optical transceiver and to determine a wavelength corresponding to the reception wavelength as a transmission wavelength for communication with the other optical transceiver, based on the wavelength information included in the optical transmission signal.

A system and method for performing an in-service optical time domain reflectometry test, an in-service insertion loss test, and an in-service optical frequency domain reflectometry test using a same wavelength as the network communications for point-to-point or point-to-multipoint optical fiber networks while maintaining continuity of network communications are disclosed.

Systems and methods for increasing throughput of a photonic processor by using photonic degrees of freedom (DOF) are provided. The photonic processor includes a multiplexer configured to multiplex, using at least one photonic DOF, multiple encoded optical signals into a multiplexed optical signal. The photonic processor also includes a detector coupled to an output of an optical path including the multiplexer, the detector being configured to generate a first current based on the multiplexed optical signal or a demultiplexed portion of the multiplexed optical signal. The photonic processor further includes a modulator coupled to and output of the detector, the modulator being configured to generate a second current by modulating the first current.

Aspects relate to a photonic processing system, a photonic processor, and a method of performing matrix-vector multiplication. An optical encoder may encode an input vector into a first plurality of optical signals. A photonic processor may receive the first plurality of optical signals; perform a plurality of operations on the first plurality of optical signals, the plurality of operations implementing a matrix multiplication of the input vector by a matrix; and output a second plurality of optical signals representing an output vector. An optical receiver may detect the second plurality of optical signals and output an electrical digital representation of the output vector.

Aspects relate to a photonic processing system, a photonic processor, and a method of performing matrix-vector multiplication. An optical encoder may encode an input vector into a first plurality of optical signals. A photonic processor may receive the first plurality of optical signals; perform a plurality of operations on the first plurality of optical signals, the plurality of operations implementing a matrix multiplication of the input vector by a matrix; and output a second plurality of optical signals representing an output vector. An optical receiver may detect the second plurality of optical signals and output an electrical digital representation of the output vector.

An encoding circuit includes an allocator to allocate a symbol to bit-strings within a first frame, a converter to convert values of target-bit-strings that exclude a predetermined-bit-string so that, as a region within the constellation is closer to a center of the constellation, a number of symbols allocated in the region is larger, a generator to generate an error-correction-code of the bit-strings, and an insertion circuit to delay the error-correction-code and insert the error-correction-code in the predetermined-bit-string within a second frame that succeeds the first frame, wherein the allocator allocates, to the bit-strings, one symbol that corresponds to the values of the target-bit-strings, the one symbol being within a quadrant that corresponds to a value of the predetermined bit-string, and wherein the converter switches, based on the value of the predetermined-bit-string, association relationships between the values of the target-bit-strings before and after the conversion.