Patent ID: 6795242
Filing Date: 2004-09-21
Classification: G02B,G02F

Abstract:
An optical circulator device for coupling three or more optical fiber ports, the device comprising:first and second refraction elements each having a refraction axis perpendicular to a propagation axis, wherein each refraction element is arranged so that light traveling in a forward direction parallel to the propagation axis and having a first linear polarization orientation is refracted by a first angle relative to the refraction axis along a refraction plane defined by the propagation and refraction axes, and light traveling in a forward direction parallel to the propagation axis and having a second linear polarization orientation perpendicular to the first polarization orientation is refracted by a second angle along the refraction plane opposite the first angle, wherein the first and second refraction elements are arranged opposite each other relative to the propagation axis, with anti-parallel refraction axes and with parallel refraction planes so that light refracted by one refraction element is refracted back parallel to the propagation axis by the other refraction element; first and second polarization orientation elements coupled to opposite ends of the first and second refraction elements, respectively, the first and second polarization orientation elements each including a Faraday rotator element and a bi-layer waveplate film deposited thereon; and first and second polanzatiofl beam splittina (PBS) films deposited on said first and second polarization orientation elements, respectively, wherein the end face of each of the first and second PBS films opposite the polarization orientation elements defines one or more port coupling regions each for coupling light signals from an optical fiber port, wherein the first and second PBS films are dimensioned and arranged so as to split a light signal in a forward direction into two parallel beams of light linearly polarized perpendicular to each other, and to combine parallel beams of light linearly polarized perpendicularly to each other in the reverse direction into a single beam of light; wherein the first polarization orientation element is arranged with respect to the first refraction element and the first PBS film so as to orient the polarization of both of the parallel light beams of a first optical signal propagating alone a forward direction from a first port coupling region on the first PBS film parallel to the first linear polarization orientation so that both beams are refracted by the first angle by the first refraction element, and to orient the polarization of two beams linearly polarized parallel to each other propagating in the reverse direction so that they are polarized perpendicular to each other; and wherein the second polarization orientation element is arranged with respect to the second refraction element and the second PBS film so as to orient the polarization of both of the parallel light beams of a second optical signal propagating along a forward direction from a second port coupling region on the second PBS film parallel to the second linear polarization orientation so that both beams are refracted by the second angle by the second refraction element, and to orient the polarization of two beams linearly polarized parallel to each other propagating in the reverse direction so that they are mutually perpendicular; whereby the first optical signal passes from the first port coupling region to the second port coupling region, and the second optical signal passes from the second port coupling region to a third port coupling region.