Patent ID: 6556746
Filing Date: 2003-04-29
Classification: G02B

Abstract:
A device, comprising:first and second separate optical paths joined to each other at two separate locations to form an input joint and an output joint, said input joint configured to receive input optical signals from either one of said first and said second optical paths and split a received optical signal into a first optical signal into said first optical path and a second optical signal into said second optical path, said output joint configured to combine said first and said second optical signals to cause optical interference therebetween, wherein at least said first optical path is formed by an optical fiber engaged to a substrate to form two optical fiber coupling ports on one side of said substrate which partially constitute said input and output joints, respectively, wherein said substrate includes first and second opposing substrate surfaces to have an elongated groove formed over said first substrate surface at each location of said input and said output joints, and at least one opening formed at one end of each elongated groove, each opening formed through said substrate to extend between said first and second substrate surfaces, wherein said optical fiber passes through each opening from said second substrate surface to said first substrate surface to have a first fiber portion disposed in said elongated groove at location of said input joint and a second fiber portion disposed in said elongated groove at location of said output joint, each of said first and said second fiber portions having a portion of fiber cladding removed to form one of said two optical fiber coupling ports to allow for evanescent coupling of energy between said first and said second optical paths, and wherein said optical fiber has a first evanescent monitoring surface located on one side of said input joint and formed by removing a portion of fiber cladding for evanescently sampling an input signal to said first and said second optical paths, a second evanescent monitoring surface located on one side of said output joint and formed by removing a portion of fiber cladding for evanescently sampling an output signal to said first and said second optical paths; a first optical detector located to receive a sample of said input optical signal from said first evanescent monitoring surface of said optical fiber; and a second optical detector located to receive a sample of said output optical signal from said second evanescent monitoring surface of said optical fiber.