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Voltage and Current to get best power out of diode

Comidt

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Hi
I don't know if this has been answered before, but tomorrow I'm getting a variable current + voltage power supply and want to run my diode off that to get best power and figure out what to tune my labby output to.
So what is the voltage and current that I'll get the most out of my little friend?
Thanks Guys ;)
 



Benm

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Re: Voltage and Current to get best power out of d

You want to run in straight off a lab supply with no external circuitry?

If its a good supply, that would be doable. I'd start out with current limiting set at 100 mA or so, voltage at zero. Connect the LD, and slowly bring up the voltage. The LD should start lasing around 2 to 2.5 volts, and the current limiting will prevent it from drawing too much.

Start with voltage at zero though! Many lab supplies have stabilizing capacitors straight on the output, after the current limiting circuitry. These can blow out your LD despite current limiting if you set current limit but connect the LD while the supply is giving a high voltage.
 

Comidt

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Re: Voltage and Current to get best power out of d

i don't know now, i thought it would be a good idea, cause of it's nice stable output
 

chimo

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Re: Voltage and Current to get best power out of d

Comidt said:
Hi
I don't know if this has been answered before, but tomorrow I'm getting a variable current + voltage power supply and want to run my diode off that to get best power and figure out what to tune my labby output to.
So what is the voltage and current that I'll get the most out of my little friend?
Thanks Guys ;)
For a laser diode, you can control current or voltage but not both. LDs (as well as other semiconductor devices) operate on a "curve".

This is important: The curve will change depending on the temperature of the device. If you initially (when it's cold) power the device with a regulated (fixed) voltage the current will rise on its own as the device heats up. If you forget and have not set the maximum current to a safe level on your power supply the LD can self-destruct quite nicely. That's why you always want to power your LD with a regulated current source.

If you read Sam's laser FAQ, there are several mentions of how lab power supplies have fried LD's due to noise on the output. I would read the FAQ because it gives tips on how to avoid this outcome and has tons of other helpful information.

Good luck. :)
 

Benm

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Re: Voltage and Current to get best power out of d

Lab supplies make good current sources though, as long as you stay in current (not voltage) limited operation it should fine regardless of diode temperature.

As for noise on the output: Try hooking your power supply with some load on it on a scope and give the controls a good twist. Most have clean outputs but there can always be a flaw or defect.
 

o_DEATH_ANG3L_o

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Re: Voltage and Current to get best power out of d

Why not just use Daedal's cicuit? It's cheap, fun, and works insanely great for laser diodes.
 

Gazoo

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Re: Voltage and Current to get best power out of d

Comidt said:
Hi
I don't know if this has been answered before, but tomorrow I'm getting a variable current + voltage power supply and want to run my diode off that to get best power and figure out what to tune my labby output to.
So what is the voltage and current that I'll get the most out of my little friend?
Thanks Guys ;)
Comidt,
I have answered this dozens of times...the GB diode will burn very good and last a long time with 160ma's applied. This seems to be sort of like a sweet spot between burning power, and diode life. Simple as that... ;)
 

catdog

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Re: Voltage and Current to get best power out of d

Be careful using a lab power supply - some have a tendency to dump their full voltage to the output when you first turn it on before correctly regulating the output. It happens regardless of what the voltage/current is set to, and only lasts for a millisecond or so (you need a oscilloscope to capture it) - but from experience it can be enough to kill laser diodes!
 

Comidt

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Re: Voltage and Current to get best power out of d

Thanks all, especially Gazoo, I will try that now.
 




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