Browse Prior Art Database

FDDI/SC Low Cost High Performance Optical Sub-assembly

IP.com Disclosure Number: IPCOM000121757D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Lasky, RC: AUTHOR [+4]

Abstract

This article is a design for Optical Sub-Assemblies (OSAs) which incorporates a two-stage alignment process and FDDI connector compatibility. The OSA's construction consists of two separate sub-assemblies which, when combined, eliminate z direction shims and reduce mechanical movement of the light source from welding during construction. These features result in lower cost and simpler manufacturing processes than previous designs.

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FDDI/SC Low Cost High Performance Optical Sub-assembly

      This article is a design for Optical Sub-Assemblies
(OSAs) which incorporates a two-stage alignment process and FDDI
connector compatibility.  The OSA's construction consists of two
separate sub-assemblies which, when combined, eliminate z direction
shims and reduce mechanical movement of the light source from welding
during construction.  These features result in lower cost and simpler
manufacturing processes than previous designs.

      The OSA's concept is as follows:  The GRIN lens is first
positioned in the lens mount.  An active alignment is then performed
into a fiber that is fixed in the equivalent xyz position of a fiber
in the finished optical sub-assembly.  The alignment process adjusts
the z position of the lens and the xy position of the housing to the
lens mount containing the GRIN lens to maximize the light launched
into the fiber.  The z positioning of the lens eliminates the
requirement for z shimming.  See Fig. 1a.

      The OSA body, ring stop and ceramic bore are then pressed
together as a separate assembly as in Fig. 1b.

      The two sub-assemblies, laser/lens and body/bore are then
brought together for a second active alignment.  This two-stage
alignment process has the advantage of not magnifying any offset
produced by welding since the lens and light source are one unit.
After this second alignment, the two sub-assemblies are then laser
welded.  See Fig. 1c.

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