Patent ID: 6404549
Filing Date: 2002-06-11
Classification: G02B

Abstract:
An optical circulator for transmitting light beams in circulation, comprising:a beam input having a first port and a second port; a beam output having a third port; a first light split/combine controller disposed between the beam input and the beam output, said first light split/combine controller comprising a first light split controller and a first light combine controller for separating a beam into an E-ray and an O-ray with perpendicular polarization directions and for combining the E-ray and O-ray with perpendicular polarization directions into one beam, respectively; a light displacement controller, which is disposed after the first light split controller and first light combine controller, to selectively induce a lateral displacement; a second light split/combine controller disposed between the light displacement controller and the beam output, said second light split/combine controller comprising a second light split controller and second light combine controller for separating a beam into an E-ray and an O-ray with perpendicular polarization directions and for combining the E-ray and O-ray with perpendicular polarization directions into one beam, respectively; a first light polarization controller, which is disposed between the first light split/combine controller and the light displacement controller for making two beams with perpendicular polarization directions travel in parallel and for making the polarization directions of the two beam traveling in parallel perpendicular; a second light polarization controller, which is disposed between the light displacement controller and the second light split/combine controller for making two beams with perpendicular polarization direction travel in parallel and for making the polarization direction of the two beams traveling in parallel perpendicular; and a light traveling direction changer, which is a reflector disposed after the light displacement controller to reflect the beam and to change its traveling direction; wherein one portion of one surface of the reflector is coated with an HR film and another portion is coated with an AR film, and the other surface as a whole is coated with an HR film, the round trip distance between the two surfaces being equal to the optical path difference in the first light split/combiner controller between the O-ray and the E-ray entering from the first port to the second port.