Jose Yee Chan

US Patent:

6424667, Jul 23, 2002

Filed:

Dec 4, 1998

Appl. No.:

09/205910

Inventors:

John G. Endriz - Belmont CA
Jose Chan - Belmont CA
Edmund L. Wolak - Palo Alto CA
G. Rainer Dohle - San Jose CA

Assignee:

JDS Uniphase Corporation - San Jose CA

International Classification:

H01S 522

US Classification:

372 36

Abstract:

Laser modules that are operated intermittently are prone to stop operating after only a few thousand cycles or less. The laser modules sometimes experience a significant increase in operating temperature before they stop operating and, in some cases, manifest an opening of the electrical circuit that connects the laser diodes in the stack of laser subassemblies. In extreme cases, the laser module disintegrates into component subassemblies. These problems arise from structural failures in affixing agents like solder that are used to affix component parts to each other. The structural failures are caused by cyclical thermal expansion and contraction of component parts that exceed the elastic limit of the solder. Resistance to global plastic deformation (creep) and to local plastic deformation (fatigue) is improved by selecting materials to reduce mechanical strain and increase resistance to creep and fatigue, by altering the structural design of the laser module to reduce mechanical strain induced into the affixing agents, and by altering operational practices to reduce the range of temperatures imposed on laser module components. One design method improves resistance to creep and fatigue by controlling the thickness of the affixing agents used to affix component parts to each other.