Browse Prior Art Database

Photodiode Array for Monitoring Individual Lasers in a Laser Array

IP.com Disclosure Number: IPCOM000044584D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Mooney, PM: AUTHOR

Abstract

An array of GaAs laser chips may be mounted on a silicon submount in which photodiodes have been fabricated so that each laser may be monitored individually. In laser array applications it is often necessary to control the output of each laser independently. While it may be possible to do this by controlling each laser sequentially using a large area photodetector, if this is not feasible, individual photodetectors must be used to monitor each laser separately. It is customary to package a discrete photodetector with a semiconductor laser for the purpose of monitoring the light output from a rear facet of the laser. It is also often the case that the laser diode is mounted on a silicon submount.

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Photodiode Array for Monitoring Individual Lasers in a Laser Array

An array of GaAs laser chips may be mounted on a silicon submount in which photodiodes have been fabricated so that each laser may be monitored individually. In laser array applications it is often necessary to control the output of each laser independently. While it may be possible to do this by controlling each laser sequentially using a large area photodetector, if this is not feasible, individual photodetectors must be used to monitor each laser separately. It is customary to package a discrete photodetector with a semiconductor laser for the purpose of monitoring the light output from a rear facet of the laser. It is also often the case that the laser diode is mounted on a silicon submount. This is especially convenient for aligning optical fibers to the lasers or when multiple lasers, which must be electrically isolated from each other, are mounted epi-side down. Electrical isolation of the individual lasers is achieved either by using intrinsic silicon or by making diffused p-n junction diodes in conducting silicon, such that when a reverse bias is applied to these p-n junction diodes, the flow of current into the silicon submount is prevented. When an array of two or more lasers is to be mounted in this fashion, an array of silicon photodiodes could be fabricated in the silicon submount such that each laser may be monitored separately by an individual photodetector. Little additional processing of the silicon is required. The drawing shows a schematic diagram of a silicon submount with two laser chips mounted on it in a side view (Fig. 1A) and top view (Fig. 1B). In order to electrically isolate the lasers, the silicon subst...