Patent ID: 7580599
Filing Date: 2009-08-25
Classification: G02B

Abstract:
1. An optical switch comprising: a plurality of ports through which a beam is input and output; an optical system through which the beam passes; a movable reflector that is enclosed in a casing and reflects, at a variable angle, the beam that has passed through the optical system; and a transmissive window that is disposed in the casing at a position through which the beam passes, is made of a uniaxial crystal, and obtains a phase difference with respect to the beam passing therethrough having a wavelength λ, the phase difference being ·λ/4 times a positive odd integer and resulting from a setting of an orientation of a crystal axis and a thickness of the transmissive window, wherein the thickness of the transmissive window is distributed in a direction in which the ports are arranged such that the phase difference is obtained irrespective of the port through which the beam passes.