Question about drivers and ripple current

Hello, everybody here knows (or should) that laser diodes need a constant current driver to last some time. Often it is mentioned, that the driver should output a low noise Voltage too.

I am thinking of building a laser but there are some questions I have about this ripple problem.
The maximal ripple current isn't mostly mentioned in any data sheet. In high power diodes almost never. So one problem with high ripple current is to over drive the diode for a short time and kill it with this small pulse of to high power, but is this the only problem?

I am asking this question because I would like to build a pulse width modulated laser to regulate the output power. Building a driver with adjustable current wouldn't be that nice because all diodes behave really non linear.
However modulating the laser would be like having a maximum of possible ripple.
Is everything fine as long as I stay under the absolute maximum rating of current during an pulse?
Can I test a laser driver with some usual silicon diodes to simulate a laser diode and test the behavior of the driver?

Greetings, MrMcChicken :yh:

MrMcChicken said:

So one problem with high ripple current is to over drive the diode for a short time and kill it with this small pulse of to high power, but is this the only problem?
...
Is everything fine as long as I stay under the absolute maximum rating of current during an pulse?
...
Can I test a laser driver with some usual silicon diodes to simulate a laser diode and test the behavior of the driver?

Click to expand...

Yes, yes, and yes.

You'll need an oscilloscope. If you're undertaking the task of building your own driver, I hope you knew that already.

Thanks for the response
Yes I know that I need some equipment to do some adequate measurements. Fortunately there is a scope, signal generator and bench power supply sitting on my desk .
I did some first rudimentary tests in LT-Spice. The driver should modulate the pulse width of the current through the diode.
I want the efficiency to be a bit better than usual linear drivers. There will be a switch mode DC/DC converter which delivers the current for the linear driver,
the regulation of the driver will work with about 7.4V (two li-ion cells). I will upload a picture of a first LT-Spice model in which I did some tests.
There are no peaks in this test and the current (R4/R3) and pulse width are separately controllable. A further test is to power this thing from a DC/DC converter to check, how it reacts to some noise at the input.

V1: Signal source for PWM
V2: 2x li-ion
V3: DC/DC converter output

Greetings, MrMcChicken :yh:

(Sorry for this crappy pictures. They are not sized optimally due to size restrictions, and I am a bit in a hurry :undecided