Polarization controller and polarization mode dispersion compensator

A polarization mode dispersion compensator comprising:

• a first polarization controller to control a state of polarization of an input modulated light such that a part of the wavelength components of the input light is in a first state of polarization;
• a demultiplexer to demultiplex the light output from the first polarization controller into a plurality of wavelength components;
• a second polarization controller including liquid crystal modulation devices to control the plurality of wavelength components to be in a second state of polarization;
• a phase controller to control the respective phases of the wavelength components, the respective states of polarization of which are controlled by the second polarization controller;
• and
• a multiplexer to multiplex the plurality of wavelength components output from the phase controller.

A polarization control method comprising:

• causing a first polarization controller to control a state of polarization of an input modulated light such that a part of the wavelength components of the input light is in a first state of polarization;
• demultiplexing, by a demultiplexer, the light output from the first polarization controller into a plurality of wavelength components;
• causing a second polarization controller including liquid crystal modulation devices to control the plurality of wavelength components to be in a second state of polarization;
• and
• multiplexing, by a multiplexer, the plurality of wavelength components output from the second polarization controller,
• wherein the demultiplexer and the multiplexer are separate.