Various embodiments of a monolithic transceiver are described, which may be fabricated on a semiconductor substrate. The monolithic transceiver includes a coherent receiver module (CRM), a coherent transmitter module (CTM), and a local oscillation splitter to feed a local oscillation to the CRM and the CTM with a tunable power ratio. The monolithic transceiver provides tunable responsivity by employing photodiodes for opto-electrical conversion. The monolithic transceiver also employs a polarization beam rotator-splitter (PBRS) and a polarization beam rotator-combiner (PBRC) for supporting modulation schemes including polarization multiplexed quadrature amplitude modulation (PM-QAM) and polarization multiplexed quadrature phase shift keying (PM-QPSK).

Various embodiments of a monolithic transceiver are described, which may be fabricated on a semiconductor substrate. The monolithic transceiver includes a coherent receiver module (CRM), a coherent transmitter module (CTM), and a local oscillation splitter to feed a local oscillation to the CRM and the CTM with a tunable power ratio. The monolithic transceiver provides tunable responsivity by employing photodiodes for opto-electrical conversion. The monolithic transceiver also employs a polarization beam rotator-splitter (PBRS) and a polarization beam rotator-combiner (PBRC) for supporting modulation schemes including polarization multiplexed quadrature amplitude modulation (PM-QAM) and polarization multiplexed quadrature phase shift keying (PM-QPSK).

An optical transmission device includes: a first receiver circuit, a second receiver circuit, a switch circuit, a terminator circuit, a packet buffer, a clock generator, and a signal generator. The first receiver circuit converts an optical signal received via a first route into a first electric signal. The second receiver circuit converts an optical signal received via a second route into a second electric signal. The switch circuit selects the first electric signal or the second electric signal. The terminator circuit extracts a packet from an electric signal selected by the switch circuit. The packet buffer stores the packet extracted by the terminator circuit. The clock generator generates a clock signal. The signal generator generates a continuous signal that includes the packet stored in the packet buffer by using the clock signal.

A quantum key distribution device is provided with an encoding unit which encodes an optical pulse train; an intensity modulating unit which subjects the encoded optical pulse train to N (where N is an integer at least equal to 3) types of intensity modulation having mutually different intensities, with different timings; and a first key distillation processing unit which generates an encryption key on the basis of a data sequence obtained by removing data obtained from an optical pulse having a specific modulation pattern from a data sequence used by the encoding unit and the intensity modulating unit.

A quantum key distribution device is provided with an encoding unit which encodes an optical pulse train; an intensity modulating unit which subjects the encoded optical pulse train to N (where N is an integer at least equal to 3) types of intensity modulation having mutually different intensities, with different timings; and a first key distillation processing unit which generates an encryption key on the basis of a data sequence obtained by removing data obtained from an optical pulse having a specific modulation pattern from a data sequence used by the encoding unit and the intensity modulating unit.

Systems and methods are provided for zero-added latency communication between nodes over an optical fabric. In various embodiments, a photonic interface system is provided that comprises a plurality of optical routing elements and optical signal sources. Each node within a cluster is assigned an intra-cluster wavelength and an inter-cluster wavelength. All the nodes in a cluster are directly connected and each node in a cluster is directly connected to one node in each of the plurality of clusters. When an optical signal from a different cluster is received at a node serving as the cluster interface, the photonics interface system allows all wavelength signals other than the node's assigned wavelength to pass through and couple those signals to an intra-cluster transmission signal. Zero latency is added in rerouting the data through an intermediate node.

Systems and methods are provided for zero-added latency communication between nodes over an optical fabric. In various embodiments, a photonic interface system is provided that comprises a plurality of optical routing elements and optical signal sources. Each node within a cluster is assigned an intra-cluster wavelength and an inter-cluster wavelength. All the nodes in a cluster are directly connected and each node in a cluster is directly connected to one node in each of the plurality of clusters. When an optical signal from a different cluster is received at a node serving as the cluster interface, the photonics interface system allows all wavelength signals other than the node's assigned wavelength to pass through and couple those signals to an intra-cluster transmission signal. Zero latency is added in rerouting the data through an intermediate node.

An optical transmission and reception system includes an optical transmitter including an optical modulator that optically modulates a transmission signal containing a known signal inserted at predetermined intervals and transmits it to an optical transmission line, and an optical receiver including an optical RC circuit that converts an optical modulation signal received from the optical transmission line into a complex time series signal, a photoelectric conversion element that converts the complex time series signal into an electrical intensity signal, and a digital signal processing unit that performs learning using the known signal as a teaching signal and performs demodulation, based on learning results, using the electrical intensity signal received from the photoelectric conversion element.

An optical transmission and reception system includes an optical transmitter including an optical modulator that optically modulates a transmission signal containing a known signal inserted at predetermined intervals and transmits it to an optical transmission line, and an optical receiver including an optical RC circuit that converts an optical modulation signal received from the optical transmission line into a complex time series signal, a photoelectric conversion element that converts the complex time series signal into an electrical intensity signal, and a digital signal processing unit that performs learning using the known signal as a teaching signal and performs demodulation, based on learning results, using the electrical intensity signal received from the photoelectric conversion element.

A communication network includes a coherent optics transmitter, a coherent optics receiver, an optical transport medium operably coupling the coherent optics transmitter to the coherent optics receiver, and a coherent optics interface. The coherent optics interface includes a lineside interface portion, a clientside interface portion, and a control interface portion.