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Thread: Wiring/Checking Laser Diodes?

  1. #1
    Join Date
    Sep 2014
    Location
    Colorado, USA
    Posts
    170

    Default Wiring/Checking Laser Diodes?

    Hi all, in a bit of a dilemma, electronics is definitely not my forte but would like some insight as to what I could be doing to help determine the polarity of laser diodes. I know laser diodes are fragile to things such as ESD and I have taken the precautions using an ESD placement mat and a ESD wriststrap and grounded myself appropriately.

    I first tested it using the diode function in my multimeter with my red diodes, got the forward voltage reading all was good.

    I tested on my blue and green diodes in a similar fashion following the pin out diagram based on the datasheets for DTRs single mode diodes, but no reading. At this point I thought I had did something wrong.

    I'm not sure what the best way to test for knowing for testing polarity of laser diodes, because it seems they are so fragile that even small amperage with an incorrect placement of the leads from your multimeter can result in a dead diode.

    I read a few points on LPF and elsewhere that it is better to use a voltage variable power supply and see if the diode lases or not... but even then if I didn't know where the positive and negative ends are suppose to go in the first place couldn't I accidentally kill the diode if I reversed the current with a very small amperage? I understand there are spec sheets for a lot of laser diodes out there that do display the pinout diagram for them. However, if I had randomly found an old laser diode and wanted to test it what is the best way to find its polarity without accidentally killing it?

    TL;DR How do I determine laser diode polarity since they are extremely sensitive to reverse current/voltages?

    I'm sorry if this is a noob question, but most of my diodes came already with their leads attached, and now I'm looking to use new bare diodes with some new mounts to better the output of my little custom build projector.

    All the best,
    Last edited by KANG; 03-28-2016 at 20:36.

  2. #2
    Join Date
    Jun 2008
    Location
    Yellowknife, NT, Canada
    Posts
    2,147,484,113

    Default

    Not really anything to add here but your multimeter may not be working with blue/green diodes because the forward voltage on those is a good chunk higher than with red diodes. I could be wrong but that seems like a reasonable explanation...

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