Potmodding/powersetting

[Toke]

How does one decide the correct current for a pump diode?

I have several pens, two app. 50mW, and now one +120mW green.
The 50mW use app. 0.5A the +120mW about 0.75A.

I am planning* on making a P/I curve for the 50mW ones and trying to find some optimal point.
Does anyone have a guideline for they would look like and where to set the "correct" current?

*2.5W Lasersbee on the way.

 

[RA_pierce]

Most 808nm diodes increase in power (pretty much) linearly with an increase in current.
Voltage should be 1.8-2.2V.

You will have to know the specs of the diode if you want to drive it within limits.

Generally, you can estimate that a 0.5W diode will want approx. 500mA for 500mW output, give or take.
For a 1W diode you should be ok with 1-1.2A.

 

[Toke]

Well, yes ok.

My question was more how to determine when the crystal set-up is getting as much power as it can take.

 

[Cyparagon]

Probably when turning up the pump power no longer increases output power as linearly.
The output as a function of pump power should have some sort of "knee"

 

[Toke]

Yes, sounds likely.

Hopefully there is something obvious on a P/I curve.

 

[RA_pierce]

When I'm pumping crystals, I like to add a good amount of heat-sinking first.

I find that it's easiest to orient the crystals for the best output (TEM00, stable power, etc.) with low pump power and then crank it up little by little and make adjustments.

You will know that your crystals are saturated if/when, like cyparagon says, the increase in green output hits a knee.
Another sign is if the green output starts to drop off quickly after 10-15 seconds of continuous operation.

I've found that the best method of setting the current on greenies is to set it conservatively so that it increases in power as it warms up instead of peaking quickly and then dropping off after a few seconds.

It helps to have an IR filter, too.

 

[Toke]

Thanks.
It will be interesting to try.

 

[anselm]

Have you seen this lady's data about her DIY green built?
Diane's Laser Page

 

[Toke]

Amazing. :bowdown:
And quite interesting how much emphasis she places on crystal temperature.
I think I will just stick to adjusting some greens for now.

 

[qumefox]

ALC60x's are 'legendary'? I know I have 3 maybe 4 of them sitting around.