An optical device and method are presented for adjusting a polarization condition of multi-channel light associated with an optical processor system (30) that has a plurality of processing units (PU) for processing linearly polarized light. The device comprises a polarization splitting/combining element (14), which may comprise a prism assembly or a birefrigerent crystal and first and second collimator arrays (12, 16). The first collimator array (12) is accommodated between a multi-channel light transmission system (20) and the polarization splitting/combining element (14). The second collimator array (16) is accommodated between the polarization splitting/combining element (14) and the optical processor system (30). The polarization splitting/combining element (14) is has predetermined dimensions and orientation to demultiplex into light of orthogonal linear polirizations light from the transmission system or multiplex into a randomly polarized light beam light from the optical processor system.