Patent ID: 7162108
Filing Date: 2007-01-09
Classification: G02B,G02F

Abstract:
1. A variable optical attenuator formed of a planar lightwave circuit that includes a waveguide structure embedded in a cladding layer supported on a substrate, the lightwave circuit containing a cross-configured π (pi)-shifted Mach Zehnder interferometer comprising: a first optical coupler having a device input and a first output and a second output; a second optical coupler having a first input and a second input and a device output; a first channel waveguide optically coupling the first output of the first optical coupler to the first input of the second optical coupler; a second channel waveguide optically coupling the second output of the first optical coupler to the second input of the second optical coupler; and respective heaters disposed on the first and second channel waveguides for selectively modifying the index of refraction of at least one of the first and second channel waveguides, thereby controlling a transmission power for selectively attenuating an optical signal; and wherein: a portion of the cladding layer on both sides of the first and second channel waveguides has been selectively removed for a predetermined length to form a channel waveguide support structure, said channel waveguide support structure comprising: