Patent ID: 6834146
Filing Date: 2004-12-21
Classification: G02B,G02F

Abstract:
A method for processing an optical communications signal, the method utilized as a DPSK demodulator and comprising the steps of:coupling at least one first-optical signal into a primary-first-optical circulator input of a first-optical circulator; splicing a primary-first-optical-circulator output port to a first 50:50 coupler input port of a 50:50 coupler; employing a secondary-first-optical circulator output port of said first optical circulator as a first-optical fiber output port of said 50:50 coupler; splicing a primary-second-optical circulator output port to a second 50:50 coupler input port of said 50:50 coupler; employing a secondary-second-optical circulator output port as a second-optical fiber output port; splicing a first 50:50 coupler output port to a first optical fiber, having a first optical fiber length, which is terminated with a first reflector that returns any optical signals back toward said 50:50 coupler; splicing a second 50:50 coupler output port to a second optical fiber, having a second length, which is terminated with a second reflector that returns any optical signals back toward said 50:50 coupler, said first and second reflectors having substantially the same reflection properties; interfering reflected signals from said first and second reflectors as they pass back through said 50:50 coupler; allowing interference products of said reflected signals to propagate back toward said first and second optical circulators, which direct said interference products to said first and second optical fiber output ports; and controlling said first and second fiber lengths and the properties of said reflectors so as to accomplish the desired optical processing in a manner that is resistant to varying environmental influences.