A wavelength selective switch comprising: one or more optical input ports configured to receive one or more input optical beams the one or more input optical beams having a plurality of wavelength channels; one or more optical output ports, each of the one or more output optical ports being configured to receive one or more wavelength channels of the plurality of wavelength channels; a first optical wavelength dispersion element configured to receive the one or more input optical beams with predetermined uniform polarization orientation and to separate the plurality of wavelength channels of the one or more input optical beams; a first polarization modulator array; polarization conditioning components configured to condition input optical beams such that the one or more input optical beams have a uniform polarization orientation; one or more switch pairs, each switch pair including a second polarization modulator array (226, 326, 330) and a birefringence element (222, 322, 328), each switch pair configured to provide a separation angle between two specified polarization orientations, and each of the first and second polarization modulator arrays (224, 226, 326, 330) having a plurality of polarizing modulation cells, wherein each cell is configured to independently change a polarization orientation of an optical beam passing through the cell; one or more optical components for directing optical beams corresponding to respective wavelength channels to respective different polarizing modulation cells of the first and second polarization modulator arrays (224, 226, 326, 330); beam folding optics arranged such that output optical beams from the arrays (224, 226, 326, 330) are returned along a return path to the output ports; a second optical wavelength dispersion element configured to combine two or more separate output optical beams from the arrays (224, 226, 326, 330) each having one or more different wavelengths, into a recombined beam having the plurality of wavelength channels; and a polarization beam splitter configured to route received recombined optical beams to particular one or more output paths according to polarization orientation, wherein the wavelength selective switch is configured to perform the output port routing separately from polarization switching by the modulator arrays (224, 226, 326, 330) on the recombined switched optical beams. one or more optical input ports configured to receive one or more input optical beams the one or more input optical beams having a plurality of wavelength channels; one or more optical output ports, each of the one or more output optical ports being configured to receive one or more wavelength channels of the plurality of wavelength channels; a first optical wavelength dispersion element configured to receive the one or more input optical beams with predetermined uniform polarization orientation and to separate the plurality of wavelength channels of the one or more input optical beams; a first polarization modulator array; polarization conditioning components configured to condition input optical beams such that the one or more input optical beams have a uniform polarization orientation; one or more switch pairs, each switch pair including a second polarization modulator array (226, 326, 330) and a birefringence element (222, 322, 328), each switch pair configured to provide a separation angle between two specified polarization orientations, and each of the first and second polarization modulator arrays (224, 226, 326, 330) having a plurality of polarizing modulation cells, wherein each cell is configured to independently change a polarization orientation of an optical beam passing through the cell; one or more optical components for directing optical beams corresponding to respective wavelength channels to respective different polarizing modulation cells of the first and second polarization modulator arrays (224, 226, 326, 330); beam folding optics arranged such that output optical beams from the arrays (224, 226, 326, 330) are returned along a return path to the output ports; a second optical wavelength dispersion element configured to combine two or more separate output optical beams from the arrays (224, 226, 326, 330) each having one or more different wavelengths, into a recombined beam having the plurality of wavelength channels; and a polarization beam splitter configured to route received recombined optical beams to particular one or more output paths according to polarization orientation, wherein the wavelength selective switch is configured to perform the output port routing separately from polarization switching by the modulator arrays (224, 226, 326, 330) on the recombined switched optical beams.