Disclosed is a transmitter that modulates a single-wavelength laser signal with multi-level amplitude modulation on each of two polarizations, with an additional multi-level inter-polarization phase modulation. In an experimental setup, four-level amplitude modulation is used on each of the two polarizations, and four-phase inter-polarization phase modulation is used. Other numbers of levels may be used, in variations of the disclosed techniques and apparatus. Also disclosed is a corresponding receiver, which includes a DSP algorithm that recovers, simultaneously, the information on the multiple intensities imprinted by the transmitter on each polarization and the information from the multi-level inter-polarization phase modulation.

Disclosed is a transmitter that modulates a single-wavelength laser signal with multi-level amplitude modulation on each of two polarizations, with an additional multi-level inter-polarization phase modulation. In an experimental setup, four-level amplitude modulation is used on each of the two polarizations, and four-phase inter-polarization phase modulation is used. Other numbers of levels may be used, in variations of the disclosed techniques and apparatus. Also disclosed is a corresponding receiver, which includes a DSP algorithm that recovers, simultaneously, the information on the multiple intensities imprinted by the transmitter on each polarization and the information from the multi-level inter-polarization phase modulation.

An optical multiplexing device includes: a control light generator that generates control lights each being a continuous wave light and a subcarrier signal based on an insertion signal having respective optical frequencies, polarized states of the control lights being perpendicular to each other; and at least one nonlinear optical medium that modulates a carrier light based on the control lights.

An optical multiplexing device includes: a control light generator that generates control lights each being a continuous wave light and a subcarrier signal based on an insertion signal having respective optical frequencies, polarized states of the control lights being perpendicular to each other; and at least one nonlinear optical medium that modulates a carrier light based on the control lights.

A communications system receives a plurality of input data streams and applies a different orthogonal function to each of the plurality of input data streams. The system processes each of the plurality of input data streams to spatially locate a first group of the plurality of input data streams onto a first carrier signal and to spatially locate a second group of the plurality of input data streams onto a second carrier signal. The system temporally locates the first carrier signal and the second carrier signal onto a third carrier signal and transmits the third carrier signal over a communications link.

An optical demultiplexer that includes at least one a hybrid phase shifter configured to receive a light signal over a fiber element, the light signal including polarized optical signals. Each phase shifter includes a thermo-optic phase shifter configured to phase shift the light signal, an electro-optic phase shifter configured to phase shift the light signal, and a coupler configured to maintain polarization of the polarized signal components. The optical demultiplexer also includes control circuitry configured to regulate the thermo-optic and electro-optic phase shifters.

Techniques are described for characterizing a receiver front end of a pluggable optical module. The pluggable optical module receives an optical signal that includes a first portion having a first polarization and a second portion having a second polarization. The first portion and second portion are not coherent with one another and the power of the first portion and second portion is equal.

Techniques are described for characterizing a receiver front end of a pluggable optical module. The pluggable optical module receives an optical signal that includes a first portion having a first polarization and a second portion having a second polarization. The first portion and second portion are not coherent with one another and the power of the first portion and second portion is equal.

A first optical network device groups a plurality of FlexO instance frames into one group, where each of the plurality of FlexO instance frames carries one OTU signal; then, performs multiplexing on the plurality of FlexO instance frames grouped into one group, to generate one first FlexO frame; next, performing scrambling and FEC processing on the first FlexO frame to generate one second FlexO frame and send it to a second optical network device. If a rate of the FlexO instance frame is 100 Gbps and two FlexO instance frames are grouped into one group, the 200 G optical module can be used in the transmission method.

A data storage system is disclosed that includes a recirculating loop storing data in motion. The data may be carried by a signal via the loop including one or more satellites or other vessels that return, for example by reflection or regeneration, the signals through the loop. The loop may also include a waveguide, for example an optical fiber, or an optical cavity. Signal multiplexing may be used to increase the contained data. The signal may be amplified at each roundtrip and sometimes a portion of the signal may be regenerated.