Patent ID: 7233717

Claim:
A reflective optical switch comprising: an input/output port portion having a plurality of fibers; a polarization separator/combiner for separating lights in the same optical path whose polarizing directions are orthogonal to each other and combining lights in different optical paths, the polarization separator/combiner including a birefringence element for separation/combination and a birefringence element for polarization dispersion compensation so that polarization dispersion is compensated for by setting the optic axis of the birefringence element for polarization dispersion compensation relative to the optic axis of the birefringence element for separation/combination so as to reverse the correspondence of two incident lights having orthogonal polarizing directions to ordinary and extraordinary lights between the two birefringence elements; a Faraday rotation angle changer; a polarization rotator for changing the relationship in polarizing direction between lights in different optical paths from orthogonal to parallel or from parallel to orthogonal; a birefringence element for optical path control for controlling optical path shift in response to polarizing direction; and a polarization rotating reflector for rotating polarizing direction 90 degrees on forward and return paths, wherein the input/output port portion, the polarization separator/combiner, the Faraday rotation angle changer, the polarization rotator, the birefringence element for optical path control, and the polarization rotating reflector are arranged along the optical path in that order, and wherein the Faraday rotation angle changer includes a Faraday element and an electromagnet for controlling 90-degree change in polarizing direction of transmitted light thereof.