Abstract: An optical polarization encoding device has been invented which allows wavelength dependent processing of polychromatic optical signals without prior separation into narrow wavelength bands. The invention comprises a stack of variable and fixed birefringent elements which introduces, on passage through the stack, a wavelength dependent polarization onto a polychromatic optical signal of arbitrary polarization. Desired polarizations are achieved simultaneously at all wavelengths contained within the incoming signal by independently varying the birefringence and/or crystallographic orientation of each element within the stack. The encoded signal may be subsequently be processed, e.g. rerouted or attenuated, as a function of wavelength using polarization dependent devices. The encoding stack is rendered polarization insensitive by dividing the incoming optical signal, with a polarization beam splitter, into two beams of orthogonal polarization prior to passage through the stack.