An information processing apparatus, includes: a memory that stores a wavelength defragmentation program; and a processor that performs, based on the wavelength defragmentation program, operations of: selecting an optical line according to a specific sequence in design information to allocate optical lines for respective optical wavelengths within a network; moving a selected optical line to a move-to optical wavelength; stopping, when movement of the selected optical line to the move-to optical wavelength is difficult, a selection of the optical line according to the specific sequence; and selecting a new optical line from optical lines indicated in a priority list.

An optical signal-to-noise ratio (OSNR) measuring device includes a processor, wherein the processor executes a process. The process includes: converting an optical signal to an electrical signal; first acquiring a signal intensity from the electrical signal; second acquiring a noise intensity of a predetermined frequency band from the electrical signal; performing a digital conversion on the noise intensity; and computing an OSNR of the optical signal based on the signal intensity and the converted noise intensity. The predetermined frequency band is a frequency band including a folding noise that occurs when the digital conversion is performed.

An S/N calculation circuit 12 to calculate the S/N ratio of a received signal, and an S/N comparison circuit 13 to compare the S/N calculated by the S/N calculation circuit 12 with a threshold Th are disposed, and a parameter setting circuit 14 controls the radiation state of a beam radiated from a transmission optical system 5 according to the result of the comparison performed by the S/N comparison circuit 13. As a result, even if the state of the propagation environment gets worse, degradation in the communication quality can be prevented and communicative stabilization can be achieved.

A device for coherent detection of data transported in an optical incoming useful signal. The device includes: a first incoming single-mode optical fibre, injecting the incoming useful signal; a second incoming single-mode optical fibre, injecting an optical signal of optical frequency substantially equal to that of the incoming useful signal, referred to as an oscillation signal, a signal mixer in which one of the signals from the first or second fibre is separated into two signals having orthogonal polarisations, and where the other one of the signals from the first or second fibre is mixed with the two separate signals, producing a mixed signal; a detector of the transported data present in the mixed signal; and an amplitude modulator configured to modulate the oscillation signal before it enters the mixer, the modulation pattern having repetitive pulses of the same interval as a symbol time of the incoming useful signal.

The invention relates to a Quantum Key Distribution system comprising a transmitter 300 and a receiver 400 for exchanging a quantum key via a quantum channel 600 through a decoy-state three state protocol wherein the transmitter comprises a transmitter processing unit 340 adapted to use random numbers from a quantum random generator to select a quantum state to encode from different states of intensity and basis, a Pulsed light source 310 adapted to generate an optical pulse, a time-bin interferometer 320 through which the generated optical pulse passes and which transforms generated optical pulse into two coherent pulses separated by the time bin duration, a single intensity modulator 360 adapted to change the intensity of the two pulses individually according to the choice made by the transmitter processing unit 340, and a variable optical attenuator 370 adapted to reduce the overall signal intensity to the optimum photon number per pulse.

Automatic optical link calibration systems and methods include an optical node with an Optical Add-Drop Multiplexer (OADM) multiplexer including a channel holder source; an optical amplifier connected to the OADM multiplexer and to a fiber span; an Optical Channel Monitor (OCM) configured to monitor optical spectrum before and after the optical amplifier; and a controller configured to obtain data associated with the fiber span including measurements from the OCM, determine settings of the channel holder source needed to meet a target launch power profile for the fiber span, and configure the channel holder source based on the determined settings.

The present invention is directed to communication systems and methods. According to an embodiment, a receiving optical transceiver determines signal quality for signals received from a transmitting optical transceiver. Information related to the signal quality is embedded into back-channel data and sent to the transmitting optical transceiver. The transmitting optical transceiver detects the presence of the back-channel data and adjusts one or more of its operating parameters based on the back-channel data. There are other embodiments as well.

A polarization demultiplexing optical communication receiver is provided with a signal quality change imparting means which imparts a signal quality change to multiplexed two optical signals; and a signal quality monitoring means which compares signal qualities of the two optical signals with each other after the multiplexed two optical signals imparted with the signal quality change are subjected to polarization separation so as to specify the two optical signals based on a result of the comparison. This makes it possible to reduce transmission characteristics degradation of a polarization-multiplexed optical signal, and to implement transmission having high reliability.

Managing performance of an optical communications network may be facilitated by digital noise loading techniques. The digital noise loading techniques may include measuring a quality of a communication signal received at a coherent optical receiver, applying digital noise to the communication signal at the coherent optical receiver, and detecting a change in the quality of the communication signal at the coherent optical receiver in response to the application of the digital noise. Based on the change in the quality of the communication signal, an operating characteristic and/or a performance margin of the coherent optical receiver may be determined, prompting or facilitating further actions such as adjusting one or more operating parameters of the optical communications network and/or triggering an alert.

Embodiments of the present application provide a visible light signal receiving and control method, a control apparatus, and a receiving device. The method comprises: determining a communication performance between a visible light signal receiving device and at least one visible light signal transmit device; and in response to an increase in the communication performance between the visible light signal receiving device and the at least one visible light signal transmit device, combining two first logic pixel units of an image sensor related to the at least one visible light signal transmit device as one second logic pixel unit to be read, when reading an inductive charge of the image sensor of the visible light signal receiving device. The method, apparatus, and device of the embodiments of the present application are capable of reducing power consumption of a visible light signal receiving device by changing the charge readout mode of an image sensor of the visible light signal receiving device in response to a change in the communication performance, and are more suitable for visible light communications in complicated mobile scenarios.