Patent ID: 6856642

Claim:
An optical resonator, comprising: a polarization dependent coupling device for coupling light having a first state of polarization into a first path, and for coupling light having a state of polarization perpendicular to said first state of polarization into a second path; a polarization modifying device; and a filter, wherein said polarization dependent coupling device receives, from a first propagation direction, a light beam having said first state of polarization, and couples said light beam to said polarization modifying device, wherein said polarization modifying device modifies a polarization of said light beam, before said light beam reenters said first path from a second propagation direction, in order to couple into said second path a portion of said light beam traveling in said second propagation direction, and wherein said filter is arranged in an optical path of said light beam after passing said polarization dependent coupling device in said first propagation direction and before reentering said polarization dependent coupling device in said second propagation direction.