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Why exactly do laser diodes need drivers? Why do LEDs just need resistors?

My understanding is that they're very similar to regular LEDs, but LEDs only need a resistor.
What makes laser diodes so special?
Are there circumstances under which laser diodes don't need a full driver circuit?

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Lasers DIODES are LED like structures. They are run in a critical way though that means that as little as 20% more voltage will destroy them, and similarly for current.

It is critically important for a laser diode driver to protect the diode from over-voltage, like even very fast noise spikes, to stop the diode failing prematurely.

jonrb (author)  steveastrouk2 years ago

Does that mean that using a capacitor to smooth any spikes would be insufficient?

Yes, unless you know exactly where to put them. Are you using this diode in a "DC" situation, or are you intending to modulate it ? If you're just running it DC, its a lot easier to be safe. Even a classic LM317 in constant current mode could be used then.

Too
much current and the laser diode will blow. Too little current and the
laser diode will not have sufficient power to turn on and operate.
Therefore, a driver circuit is needed to give precisely the correct
range of current needed so that our diode will operate. Lasers diodes
are more like 3.5 volts and 150 ma and more. So, unlike LEDs that just
need a resistor to limit the current, laser diodes need a driver to push
the right current.

For more detailed info you can visit :

You can also visit : Laser Driver

rickharris2 years ago

I am going to go nuts soon - I penned a fairly long response to this question which has subsequently disappeared.

Have a look here

https://www.instructables.com/id/How-electricity-an...

It may help you understand how these things work.

Lasers and LEDs work differently.

LEDs will work high voltage ranges like 3 to 70 volts and low current like 5 ma.

Lasers diodes are more like 3.5 volts and 150 ma and more.

So LEDs just need a resistor to limit the current and laser diodes need a driver to push the right current.