An optical device and method are presented for adjusting a polarization condition of multi-channel light associated with an optical processor system that has a plurality of processing units for processing linearly polarized light. The device comprises a polarization splitting/combining element, and first and second collimator arrays. The first collimator array is accommodated between a multi-channel light transmission system and the polarization splitting/combining element. The second collimator array is accommodated between the polarization splitting/combining element and the optical processor system. The polarization splitting/combining element is has predetermined dimensions and orientation to carry out at least one of the following: concurrently receiving all randomly polarized light beams of the multi-channel light coming from the transmission system and producing from each of the received beams a pair of light components of orthogonal linear polarizations; and concurrently receiving all linearly polarized light components of the multi-channel light coming from the optical processor system and for each channel combining a pair of orthogonally polarized light components into a randomly polarized light beam.