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.

According to an aspect of an embodiment, operations may include receiving a light wave and generating a pumping wave by performing polarization modulation on the light wave based on a bit stream. The pumping wave may include a first polarization component having a first polarization and a second polarization component having a second polarization and having a same wavelength as the first polarization component. The operations may also include emitting the pumping wave in an optical medium such that the pumping wave amplifies an optical signal propagating within the optical medium.

According to an aspect of an embodiment, operations may include receiving a light wave and generating a pumping wave by performing polarization modulation on the light wave based on a bit stream. The pumping wave may include a first polarization component having a first polarization and a second polarization component having a second polarization and having a same wavelength as the first polarization component. The operations may also include emitting the pumping wave in an optical medium such that the pumping wave amplifies an optical signal propagating within the optical medium.

A coherent optical transmitter is in operable communication with an optical fiber an includes a plurality of analog-to-digital converters (ADCs) configured to (i) receive a plurality of radio frequency analog input signals, respectively, and (ii) convert the received plurality of RF analog input signals into a plurality of respective digital data streams. The transmitter further includes a source laser configured to output at least two orthogonal polarization component signals, and at least two polarization modulators configured to modulate (i) an in-phase portion output from a first ADC, (ii) an in-quadrature portion output from a second ADC, and (iii) one polarization component signal of the at least two orthogonal polarization component signals. The transmitter further includes a polarization beam combiner configured to (i) multiplex the respective outputs of the at least two polarization modulators, and (ii) transmit the multiplexed output from the polarization beam combiner to the optical fiber.

A coherent optical transmitter is in operable communication with an optical fiber an includes a plurality of analog-to-digital converters (ADCs) configured to (i) receive a plurality of radio frequency analog input signals, respectively, and (ii) convert the received plurality of RF analog input signals into a plurality of respective digital data streams. The transmitter further includes a source laser configured to output at least two orthogonal polarization component signals, and at least two polarization modulators configured to modulate (i) an in-phase portion output from a first ADC, (ii) an in-quadrature portion output from a second ADC, and (iii) one polarization component signal of the at least two orthogonal polarization component signals. The transmitter further includes a polarization beam combiner configured to (i) multiplex the respective outputs of the at least two polarization modulators, and (ii) transmit the multiplexed output from the polarization beam combiner to the optical fiber.

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.

A radio communication system for duplex communication comprising an optical carrier generator for generating optical carrier signals, a local oscillator (LO) for generating an electrical signal in a radio communication band, an information signal source, electro-optic modulators driven directly at an input electrical port by said information signal and said LO signal to modulate a portion of said optical carrier signal to form a modulated portion being an optical band information signal for transmission over an optical link; and a photodetector remote from said electro-optic modulators for receiving said transmitted optical band information signal from said optical link, and directly generating an electrical signal that is up-converted for radio transmission, or down-converted to a baseband frequency.

A radio communication system for duplex communication comprising an optical carrier generator for generating optical carrier signals, a local oscillator (LO) for generating an electrical signal in a radio communication band, an information signal source, electro-optic modulators driven directly at an input electrical port by said information signal and said LO signal to modulate a portion of said optical carrier signal to form a modulated portion being an optical band information signal for transmission over an optical link; and a photodetector remote from said electro-optic modulators for receiving said transmitted optical band information signal from said optical link, and directly generating an electrical signal that is up-converted for radio transmission, or down-converted to a baseband frequency.

A polarization scrambler using a retardance element (RE) is disclosed. The polarization scrambler may include an optical fiber input to transmit an optical signal, and a beam expander to receive and expand the optical signal to create an expanded optical signal. The polarization scrambler may include a retardance element (RE) to cause a polarization scrambling effect on the expanded optical signal and to create a scrambled expanded optical signal. The polarization scrambler may include a beam reducer to receive and reduce the scrambled expanded optical signal to create a scrambled optical signal. The polarization to scrambler may include an optical fiber output to receive scrambled optical signal. The optical fiber output may transmit the scrambled optical signal to one or more downstream optical components.