Wavelength selective switch

A reconfigurable optical add-drop multiplexer (ROADM) device, comprising at least one wavelength selective switch,

• wherein each of the at least one wavelength selective switch comprises:
• a plurality of optical fibers, configured to receive an optical input signal transmitted by a light source, wherein the plurality of optical fibers comprise a reference optical fiber and at least one other optical fiber, and a fiber core of each of the at least one other optical fiber has a first distance relative to a fiber core of the reference optical fiber in a height direction of the wavelength selective switch, the height direction is a direction perpendicular to a longitudinal axis of the plurality of optical fibers, and the height direction is a switching direction of a beam in the wavelength selective switch and is perpendicular to a dispersion direction of the beam;
• a multiplexing/demultiplexing component, configured to split the optical input signal into a plurality of single-wavelength optical signals in space along the dispersion direction perpendicular to the height direction;
• and
• a liquid crystal on silicon (LCOS) including an array of pixels, wherein the LCOS is configured to:
• receive the plurality of single-wavelength optical signals;
• and
• apply a voltage to a pixel in a location covered by each of the plurality of single-wavelength optical signals, and change a refractive index of a corresponding liquid crystal to change a phase of the single-wavelength optical signal so that an offset of a diffraction spectrum for the single-wavelength optical signal transmitted via the respective other optical fiber is compensated by the first distance of the respective other optical fiber, wherein the offset of the diffraction spectrum is an offset relative to a specified location of a center wavelength on the LCOS, and indicates how far the diffraction spectrum deviates from the specified location of the center wavelength on the LCOS,
• wherein the plurality of optical fibers is further configured to output an optical output signal obtained after the optical input signal is processed by the wavelength selective switch.