Integrated optical device with polarization based signal routing

An optical filtering device which comprises:

• a polarization diversity means for splitting an incoming beam of light into two orthogonally polarized sub-beams and for rotating the polarization state of at least one of the polarized sub-beams to provide two sub-beams having a same polarization orientation,
• a routing block having an input port, for directing a polarized light beam launched into the input port along a first path, in one of two directions in dependence upon the polarization state of the polarized light beam,
• an optical filter element for filtering a characteristic of the beam, the filter being optically coupled with the routing block for allowing a first portion of the polarized beam launched into said routing block to pass through said filter and for reflecting a second portion of the beam back to the routing block to follow a second path, and
• a rotator for rotating the polarization of the second portion of the beam so that it follows the second path after reflection from the optical filter element.

A method of routing a polarized optical signal beam comprising

• launching the polarized optical signal beam into a birefringent block having a first end face and a second end face,
• reflecting the signal beam alternatively at the first and the second end face to effect a plurality of reflections,
• rotating the polarization of the signal beam at at least some of the reflections to effect an angular displacement of the signal beam in the birefringent block upon reflection of the beam,
• whereby the signal beam is routed along a zig-zag path through the birefringent block.