Patent ID: 6185345
Filing Date: 2001-02-06
Classification: G02B

Abstract:
An unbalanced Mach-Zehnder interferometer comprising:first and second fused tapered couplers, each fused tapered coupler being responsive to the reception of at least one first and second optical input signals for generating separate predetermined first and second optical output signals, wherein the first and second output signals from the first fused tapered coupler are coupled via first and second optical waveguides, respectively, to respective first and second optical inputs of the second fused tapered coupler, and first and second output signals from the second fused tapered coupler are provided as first and second output signals from the unbalanced Mach-Zehnder interferometer; andvariable delay providing means coupled in one of the first and second waveguides coupling the first and second optical output signals from the first fused tapered coupler to the first and second optical inputs of the second fused tapered coupler for introducing a predetermined variable delay into an optical signal passing therethrough for maintaining a relative delay between the first and second waveguides at a constant value.