Ian Jeremiah Hutagalung

US Patent:

20050135728, Jun 23, 2005

Filed:

Dec 17, 2004

Appl. No.:

11/015223

Inventors:

Anca Sala - Troy MI, US
Duncan Harwood - Santa Clara CA, US
Barthelemy Fondeur - Mountain View CA, US
Anantharaman Vaidyanathan - Cupertino CA, US
Robert Brainard - Sunnyvale CA, US
Sanjay Thekdi - Santa Clara CA, US
Thomas Nguyen - San Jose CA, US
Ian Hutagalung - San Jose CA, US

Assignee:

JDS UNIPHASE CORPORATION - San Jose CA

International Classification:

G02B006/12

US Classification:

385014000, 385140000

Abstract:

The invention relates to a variable optical attenuator constructed as a Mach Zehnder planar lightwave circuit, particularly including a channel waveguide support structure for heat isolation and stress relief to reduce polarization dependent loss (PDL) and power consumption in the device. Power reduction trenches comprise longitudinal segments having small stress relief pillars of cladding material left in between them in the etching process. The waveguides of the MZI are supported by a main pillar structure and integral stress relief pillars which remain after removal of the trenches. The waveguide is surrounded by air on three sides for improved heat isolation. The performance of the present invention shows substantial improvement in PDL and extinction ratio over the prior art continuous trench design, and also, to a smaller degree, over the case where power reduction trenches are not used at all. Segmented trenches appear to allow for the lowest stress on the two waveguide arms of all the cases including no trench and trenched devices.