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Method for Compensating Optical Power Droop Induced From Cross-Talk in A Multibeam Laser Diode Array

IP.com Disclosure Number: IPCOM000101699D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Fouere, JC: AUTHOR

Abstract

This article describes a method to improve control of the light output power of individual beams in a laser diode array. This is accomplished by compensating for change in overall efficiency (of an individual laser diode). Whenever adjacent laser diodes are operating, the compensation is achieved by modifying the drive current for that laser diode in proportion to the drive currents of the adjacent laser diodes.

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Method for Compensating Optical Power Droop Induced From Cross-Talk in A Multibeam Laser Diode Array

       This article describes a method to improve control of the
light output power of individual beams in a laser diode array.  This
is accomplished by compensating for change in overall efficiency (of
an individual laser diode).  Whenever adjacent laser diodes are
operating, the compensation is achieved by modifying the drive
current for that laser diode in proportion to the drive currents of
the adjacent laser diodes.

      As an illustration, consider a two-beam laser diode array where
laser diode LD(1) is operated with a constant drive current Id(1) and
laser diode LD(2) is modulated with a square-wave drive current
Id(2).

      In the prior art, as illustrated in Fig. 1, light output from
laser LD(1) would demonstrate some amount of modulation as a result
of coupling between the two laser diodes LD(1) and LD(2).

      The present method proposes a way to reduce the amount of
modulation in beam 1 by feedforwarding to laser diode LD(1) a known
amount of drive current.  This is shown graphically in Fig. 2.

      Fig. 3 illustrates one embodiment of the invention.  It makes
use of logically addressable current sources.  The level of each
current source is adjusted by calibration so as to compensate exactly
any change in the optical power output of laser diode LD(1).

      This particular embodiment can be extended to each individual
laser...