An optical module has an optical modulator configured to perform phase modulation on each of divided light components of an input light and output at least two phase-modulated signal lights, a semiconductor optical amplifier configured to amplify the phased-modulated signal lights in a same polarization mode, and a polarization multiplexer configured to convert the amplified signal lights into two orthogonally polarized signal lights and multiplex the orthogonally polarized signal lights.

An optical transceiving apparatus includes an optical transmitting device performing polarization multiplexing on and transmitting as polarization multiplexed signal light, a first signal light of a predetermined polarization direction and a second signal light of a polarization direction different from the predetermined polarization direction; an optical receiving device receiving the signal light transmitted from the optical transmitting device through an optical transmission path; an acquiring unit acquiring information indicative of magnitude relation of intensity between the first signal light and the second signal light included in the signal light received by the optical receiving device; and a control unit controlling the magnitude relation of intensity between the first signal light and the second signal light included in the signal light output from the optical transmitting device, to be opposite to the magnitude relation indicated by the information acquired by the acquiring unit.

An optical transceiving apparatus includes an optical transmitting device performing polarization multiplexing on and transmitting as polarization multiplexed signal light, a first signal light of a predetermined polarization direction and a second signal light of a polarization direction different from the predetermined polarization direction; an optical receiving device receiving the signal light transmitted from the optical transmitting device through an optical transmission path; an acquiring unit acquiring information indicative of magnitude relation of intensity between the first signal light and the second signal light included in the signal light received by the optical receiving device; and a control unit controlling the magnitude relation of intensity between the first signal light and the second signal light included in the signal light output from the optical transmitting device, to be opposite to the magnitude relation indicated by the information acquired by the acquiring unit.

A control device which controls an operation of a compensation device which compensates for birefringence and/or polarization mode dispersion, which is received by signal light having propagated through an optical transmission line, by digital signal processing using a finite impulse response filter includes: a detection signal reception unit which receives a detection signal which is a signal indicating a detection result of a detection device which optically detects polarization fluctuation in the optical transmission line; and a setting unit which decides a setting regarding an update frequency or an update interval of the number of taps of the finite impulse response filter or an update frequency or an update interval of a tap coefficient of the finite impulse response filter, based on the detection result of the detection device.

Systems and methods for performing polarization compensation in optical fiber-based quantum telecommunications systems are provided. The system includes a polarization modulator optically coupled to a photon source by an optical fiber and at least one controller coupled to the polarization modulator. The at least one controller is configured to determine, using a machine learning model and/or a lookup table, a feedback parameter based on one or more measurements of a polarization of probe photons at a location along the optical fiber, the probe photons being generated by the photon source; and using the feedback parameter, to change a setting of the polarization modulator to change a polarization of quantum data photons propagating in the optical fiber subsequent to the probe photons.

A method includes separating, by a polarization splitter rotator, an input light signal into a first light signal having a first insertion loss and a second light signal having a second insertion loss that is different than the first insertion loss; and attenuating, by an optical attenuator, the first light signal or the second light signal in order to compensate for a polarization dependent loss between the first light signal and the second light signal such that a total optical power of the first light signal and the second light signal is independent of a polarization state of the input light signal.

A polarization fluctuation detection apparatus receives a plurality of optical signals output from the transmitter through a transmission line through which the plurality of optical signals are transmitted in a predetermined direction at propagation velocities different from each other. The polarization fluctuation detection apparatus includes a fluctuation detection unit configured to detect polarization fluctuations of the plurality of received optical signals, and an estimation unit configured to estimate a position where the polarization fluctuation has occurred in the transmission line based on a difference between the times at which the polarization fluctuations are detected in the plurality of optical signals.

A method of transmitting information comprising the steps of: (a) transmitting at least one photon via a fibre; (b) characterizing the fibre by determining at least one depolarization loss caused by the fibre; and (c) compensating for polarization altering effects of the fibre; wherein a single photon source is used for delivery of individual polarized photons in harsh environments.

The disclosed systems and methods are for reducing polarization dependent loss in an optical link including: i) changing, by a state of polarization (SOP) controller, an SOP of an optical signal propagating in the optical link; ii) computing, by a link controller, a polarization dependent loss (PDL) in a portion of the optical link; iii) generating, by the link controller, a control signal according to the PDL; and iv) based on the control signal, changing, by the SOP controller, the SOP of the optical signal.

The present invention relates to a method and a device for dual-polarisation, fiber-optic SDM transmission. The transmission method uses specific I/Q coding that makes it possible to combat the effects of PDL. The modulation symbols to be transmitted on the 2N polarisation states of the N basic spatial channels are broken down into real and imaginary values (220). A real vector composed by concatenating these real values and imaginary values is then constructed. A first invertible linear transformation, represented by a dense real matrix, is applied (230) to the resulting real vector to provide a transformed real vector. Complex transmission symbols are formed by I/Q combination (240) of the components of the transformed vector, the transmission symbols then modulating the different polarisation states of the basic spatial channels.