Patent ID: 6028684
Filing Date: 2000-02-22
Classification: G01M,H04B

Abstract:
An optical transmission system comprising:a first optical fiber, said first optical fiber having an input and an output;a second optical fiber, said second optical fiber having an input and an output;a third optical fiber, said third optical fiber having an input and an output;a fourth optical fiber, said fourth optical fiber having an input and an output;a first optical isolator coupled to said output of said first optical fiber, said first optical isolator having an input and an output;a second optical isolator coupled to said output of said third optical fiber, said second optical isolator having an input and an output;an optical coupler having four ports and coupled to the output of said first optical isolator, the input of said second optical fiber, the output of said second optical isolator, and the input of said fourth optical fiber;a first path through said optical coupler coupling the input of said first optical fiber to the input of said second optical fiber;a second path through said optical coupler coupling the input of said second optical fiber to the input of said fourth optical fiber;a third path through said optical coupler coupling the input of said third optical fiber to the input of said fourth optical fiber; anda fourth path through said optical coupler coupling the input of said fourth optical fiber coupler to the input of said second optical fiber.