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Current Injection Technique for In-Situ Characterization of Laser Diode Life Tester

IP.com Disclosure Number: IPCOM000120547D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Harding, RF: AUTHOR [+2]

Abstract

A current injection technique has been utilized to perform an in-situ power versus current (P-I) measurement on the laser life tester. This new method extends the function of automatic power control (APC) module such that laser characterization can be done without having to remove the laser diodes from the tester. Damages to the device due to either electrostatic discharge (ESD) or physical handling can be avoided. Furthermore, since disturbances to the tester thermal environment can be minimized, laser lifetime prediction can be done with more confidence.

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Current Injection Technique for In-Situ Characterization of Laser
Diode Life Tester

      A current injection technique has been utilized to
perform an in-situ power versus current (P-I) measurement on the
laser life tester.  This new method extends the function of automatic
power control (APC) module such that laser characterization can be
done without having to remove the laser diodes from the tester.
Damages to the device due to either electrostatic discharge (ESD) or
physical handling can be avoided.  Furthermore, since disturbances to
the tester thermal environment can be minimized, laser lifetime
prediction can be done with more confidence.

      In the evaluation of laser diode reliability, under a constant
light output condition, a commercially available integrated circuit
module is often used in the design of laser life testers to serve as
an automatic power control (APC).

      As the device ages, a decrease in the laser light output will
occur which results in a drop in monitor diode current.  The APC
circuit is designed to sense this monitor current drop and will
increase in the laser drive current until its optical power is
restored to its original value.

      In order to perform the in-situ laser P-I curve measurements on
the life tester, a current source is provided by a 12-bit D/A
converter on a card from within the controller of the life tester.
This variable current is applied to the cathode of the monitor diode
(MD), as shown in Fig...