Optical arrangement for suppressing outerband crosstalk in a wavelength selective switch

Abstract

An optical device includes at least three optical ports. An optical arrangement arranges an optical beam received from any of the optical ports into a first polarization state. A dispersion element spatially separates the optical beam into a plurality of wavelength components. An optical power element converges each wavelength component in at least one direction. A programmable optical phase modulator steers the wavelength components through the optical arrangement, the dispersion element and the focusing element to a selected optical output. The programmable optical phase modulator includes an active area that performs the steering and a non-active area surrounding the active area. A polarizing arrangement located in an optical path between at least one of the optical ports and at least a portion of the non-active area of the programmable optical phase modulator is configured to arrange optical energy into a second polarization state orthogonal to the first polarization state.