First transmission device includes a first counter that generates counter value incremented in a specified cycle. Second transmission device includes a second counter that. generates counter value incremented in the specified cycle. Polarization variation monitoring device acquires a first counter value generated by the first counter and a second counter value extracted by the first transmission device from a received frame transmitted from the second transmission device when the first transmission device detects polarization variation, and a third counter value generated by the second counter and a fourth counter value extracted by the second transmission device from a frame transmitted from the first transmission. device when the second detector detects the polarization variation. The polarization variation monitoring device determines an occurrence position of the polarization variation based on the first counter value, the second counter value, the third counter value and the fourth counter value.

First transmission device includes a first counter that generates counter value incremented in a specified cycle. Second transmission device includes a second counter that. generates counter value incremented in the specified cycle. Polarization variation monitoring device acquires a first counter value generated by the first counter and a second counter value extracted by the first transmission device from a received frame transmitted from the second transmission device when the first transmission device detects polarization variation, and a third counter value generated by the second counter and a fourth counter value extracted by the second transmission device from a frame transmitted from the first transmission. device when the second detector detects the polarization variation. The polarization variation monitoring device determines an occurrence position of the polarization variation based on the first counter value, the second counter value, the third counter value and the fourth counter value.

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.

An optical transmitter transmits a data signal. The optical transmitter has an encoder configured to encode the data signal by selecting based on a bit sequence a first symbol and a second symbol from a set of four symbols for each one of at least two transmission time slots. The optical transmitter further has a modulator configured to use in each transmission time slot the first symbol to modulate a first carrier wave and the second symbol to modulate a second carrier wave, and to transmit the two carrier waves over orthogonal polarizations of an optical carrier. Symbols in consecutive transmission time slots have non-identical polarization states.

An optical transmitter transmits a data signal. The optical transmitter has an encoder configured to encode the data signal by selecting based on a bit sequence a first symbol and a second symbol from a set of four symbols for each one of at least two transmission time slots. The optical transmitter further has a modulator configured to use in each transmission time slot the first symbol to modulate a first carrier wave and the second symbol to modulate a second carrier wave, and to transmit the two carrier waves over orthogonal polarizations of an optical carrier. Symbols in consecutive transmission time slots have non-identical polarization states.

An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

An injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

Systems of enhancing contrast of lighting can include a light-transmitting subsystem having a light source to emit a stream or light-signal pulses and an encoding circularly polarizing filter to optically encode the stream of light-signal pulses with circular polarization, and a light-receiving subsystem including a decoding circularly polarizing filter to optically decode the circular polarization of the stream of light-signal pulses and a light imager to receive the stream of light-signal pulses after being optically decoded by the decoding circularly polarizing filter. In another example, the system can include a polarimetric light imaging assembly, a light source to generate a stream of light-signal pulses directed at the polarimetric light imaging assembly, and a control system to synchronously control the light-signal pulses to be emitted from the light source in timed correlation with a component(s) of the polarimetric light imaging assembly.

Systems of enhancing contrast of lighting can include a light-transmitting subsystem having a light source to emit a stream or light-signal pulses and an encoding circularly polarizing filter to optically encode the stream of light-signal pulses with circular polarization, and a light-receiving subsystem including a decoding circularly polarizing filter to optically decode the circular polarization of the stream of light-signal pulses and a light imager to receive the stream of light-signal pulses after being optically decoded by the decoding circularly polarizing filter. In another example, the system can include a polarimetric light imaging assembly, a light source to generate a stream of light-signal pulses directed at the polarimetric light imaging assembly, and a control system to synchronously control the light-signal pulses to be emitted from the light source in timed correlation with a component(s) of the polarimetric light imaging assembly.

An optical transmitter transmits a data signal. The optical transmitter has an encoder configured to encode the data signal by selecting based on a bit sequence a first symbol and a second symbol from a set of four symbols for each one of at least two transmission time slots. The optical transmitter further has a modulator configured to use in each transmission time slot the first symbol to modulate a first carrier wave and the second symbol to modulate a second carrier wave, and to transmit the two carrier waves over orthogonal polarizations of an optical carrier. Symbols in consecutive transmission time slots have non-identical polarization states.