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Driving a Diode laser with an Analog Signal

SeaJay

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Oct 29, 2025
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I was wondering if anyone had experience driving a laser diode with a modulated intensity.

For a side project I am toying with, I want to modulate an audio signal onto the intensity of a red laser say [something like this](https://www.farnell.com/datasheets/3215790.pdf)

I imagine I can use a linear voltage regulator to get the voltage right for this application, but I am a little stuck on how to vary the current.

I imagine there is a method of making an OpAmp do this, but I don't have a whole lot of experience with the electronics side of things. So I was hoping others here might be able to point me in the right direction

Cheers!
 





Ths link didn't get formatted correctly. But it is a pretty standard 3 pin, 635nm 7mW diode laser
 
"The Laser Cookbook" by Gordon McComb has several methods in great detail.
 
"The Laser Cookbook" by Gordon McComb has several methods in great detail.
Brilliant, chapter 13 describes the thing i am trying to do exactly!

In case any future readers stumble across the thread, here is the circuit diagram the book suggests. (since there is nothing worse when googling than finding a thread describing your problem, shortly followed by a "I fixed it" and no answer)
 

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