Patent ID: 6438278
Filing Date: 2002-08-20
Classification: G02B

Abstract:
A fiber optical circulator, comprising:a. first dual core glass capillary for housing two optical fibers of a first port and a third port respectively; b. a first collimator lens for collimating a light beam from said first port; c. a first birefringent crystal for dividing said collimated light beam into two orthogonal components with a displacement; d. a first Faraday rotator for rotating the state of polarization of said two components; e. a first pair of half-wave plates each for passing a respective one of said two components, and causing said two components to be in the same state of polarization in a particular direction; f. a crystal prism having a planar portion with an optical axis designed to allow light components polarized in said particular direction to pass without displacement but create a displacement in light components polarized in another direction perpendicular to said particular direction, such that said two components in the same state of polarization in said particular direction passes the crystal prism without displacement, and said crystal prism further having a prism portion with symmetrical surfaces having a prism angle designed to correct the angles of said two components, causing said two components to be parallel to a central axis of said circulator; g. a second pair of half-wave plates each for passing a respective one of said two components, and changing the state of polarization of said two components; h. a second Faraday rotator for rotating the state of polarization of said two components to be orthogonal; i. a second birefringent crystal for combining said two orthogonal components into a combined light beam; j. a second collimator lens for focusing said combined light beam; k. a second dual core glass capillary for housing another optical fiber of a second port to receive said combined light beam; and l. said circulator providing a circulating path for a light beam from said optical fiber of said second port to be circulated into said optical fiber of said third port, and further expandable to a four or more ports optical circulator based on the angle correction property of said symmetrical surfaces of said prism portion of said crystal prism.