Tunable optical dispersion compensators

An apparatus comprising:

• an input variable optical coupler including output ports, the input variable optical coupler coupled to selectively split portions of an optical signal received from an optical input port into each of the output ports;
• optical dispersion paths each coupled to one of the output ports of the input variable optical coupler to impart dispersion compensation to each of the split portions of the optical signal;
• an output variable optical coupler including input ports each coupled to one of the optical dispersion paths to selectively combine the split portions of the optical signal;
• an optical output port coupled to the output variable optical coupler to output a dispersion compensated optical signal;
• an optical demultiplexer disposed between the optical input port and the input variable optical coupler;
• and
• an optical multiplexer disposed between the output variable optical coupler and the optical output port.

A method of dispersion compensation, comprising:

• splitting an optical signal into first and second portions based on a first tunable splitting ratio;
• applying a first dispersion compensation function to the first portion by propagating the first portion along a first dispersion path;
• applying a second dispersion compensation function to the second portion by propagating the second portion along a second dispersion path;
• recombining the first and second portions based on a second tunable splitting ratio;
• outputting a dispersion compensated version of the optical signal;
• and
• adjusting an overall dispersion compensation between the first dispersion compensation function and the second dispersion compensation function by changing the first and second splitting ratios.

A method of dispersion compensation, comprising:

• demultiplexing a multi-channel optical signal into two input groups of channels;
• coupling a first portion from each of the two input groups of channels into a first dispersion path and a second portion from each of the two input groups of channels into a second dispersion path, based on a first tunable coupling ratio;
• applying a first dispersion compensation function to the first portion by propagating the first portion along the first dispersion path;
• applying a second dispersion compensation function to the second portion by propagating the second portion along the second dispersion path;
• coupling the first and second portions from the first and second dispersion paths into two output groups of channels, based on a second tunable coupling ratio;
• and
• multiplexing the two output groups into a dispersion compensated multi-channel optical signal.

An optical receiver, comprising:

• a processor coupled to synchronous dynamic random access memory (“SDRAM”), the processor to store and manipulate electrical data in the SDRAM;
• an optical-to-electrical (“O-E”) converter coupled to the processor to convert optical data to the electrical data;
• and
• a dispersion compensation unit coupled to the O-E converter, the dispersion compensation unit including:
• an input variable optical coupler including output ports, the input variable optical coupler coupled to selectively split portions of the optical data into each of the output ports;
• optical dispersion paths each coupled to one of the output ports of the input variable optical coupler to impart dispersion compensation to each of the split portions of the optical data, wherein each of the optical dispersion paths includes a bus waveguide and a plurality of cascaded racetrack resonators optically coupled along the bus waveguide;
• and
• an output variable optical coupler including input ports each coupled to one of the optical dispersion paths to selectively combine the split portions of the optical data.