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Alignment Detector on Silicon Optical Bench

IP.com Disclosure Number: IPCOM000048261D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Comerford, LD: AUTHOR [+2]

Abstract

Proper alignment of an injection laser die with respect to a silicon optical bench subcarrier may be automatically detected by providing two contacts on the silicon optical bench which both make simultaneous electrical contact to the laser metal pad if, and only if, the laser die is properly positioned.

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Alignment Detector on Silicon Optical Bench

Proper alignment of an injection laser die with respect to a silicon optical bench subcarrier may be automatically detected by providing two contacts on the silicon optical bench which both make simultaneous electrical contact to the laser metal pad if, and only if, the laser die is properly positioned.

Fig. 1 is a cross-sectional view of a bonded laser die in contact with two alignment sensing contacts 10, 12. The contacts may be defined by photolithographic delineation of a metal layer 14 isolated from the silicon subcarrier 16 by an oxide layer 18. Ab The contacts may be arranged so that a continuous electrical path is formed only when proper alignment is achieved by having the contacts touch only a small region of the gold metal pad 20 of the laser die 22 at opposite diagonal corners of the metal pad. This is shown better in Fig. 2, which is a schematic top view of a silicon optical bench with a registered laser die 22. Also shown in Fig. 2 are lens groove 24, output fiber groove 26, solder bonding channels 28 and solder reservoir 30. Electrical continuity between contacts 10 ind 12 indicates proper laser die registration. Because the diagonal is the longest length on the laser contact pad and the pad size and position (with respect to the laser active region) are well defined, there will be no continuity unless the die is properly aligned and squarely placed on the bonding channel.

This method of detecting proper a...