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big problems with sharp 185 mW 638 nm diodes

reloader45

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Hello,

today I got two sharp laser diodes
Sharp GH0631IA2G 185mW 638nm Laser Diode

from DTR.

I pressed one into a 12 mm Copper heatsink from DTR and connected it to a brand new 500 mW driver from X-wossee.

Nothing happened! No current, no laser light. After that, I connected the diode direct to a power supply, set to 100 mA. There was only a little red glow. After raising the current to 280 mA,m the output was under 1 mW.
The same thing with the other diode. The result, 75€ blown in the wind. I also checked the data sheet of this diodes. They should have a normal polarity.
I am really confused what happend. Next time I will connect new diodes first to a LM317 laser driver, they are more robust than this expensive laser driver.
Maybe DTR has an idea what went wrong.

best regards

Edgar
 



reloader45

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Hello,


attached, you can find a photo of the pressed diode.

sharp 185 mW 638 nm.jpg

best regards

Edgar
 

diachi

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How did you set the current on the driver?

Did you use any ESD protection while handling?

No current suggests incorrect polarity. Be nice if the datasheet was more clear.

Looks like it could be pressed a little further too. Hard to tell with that picture. Should be fine for testinf and soldering though.
 
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reloader45

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Hello,

I got two 500 mA drivers today from X-.wossee. They are set below 100 mA. I tested the remaining driver with a dummy load, it works fine as usual.
I will see what DTR will answer. Maybe it helps to extract the diodes, to see if I got the correct diodes.


best regards

Edgar
 

paul1598419

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From your photo it does look like the diode is not seated all the way into the copper module. Much of the ability to transfer heat comes from seating the diode's rim to the self that the diode seats against. I don't think this caused your problem, but it will cause you another problem if duplicated with a good diode.
 

reloader45

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Hello,

below one photo of the extracted diode and one photo of the second diode. All I could find was the number on the bottom of the diode.
Is that new for the sharp diodes?

sharp 3.jpgsharp 2.jpg


best regards

Edgar
 

reloader45

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Hello,

I set all my 5,6 mm diodes this way, so that the back of the module touches the bottom of diode to get an additional heat transfer.


best regards

Edgar
 

paul1598419

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Not all Sharp diodes have SB numbers around the window. It is nice when they do as I have used them for showing different pinouts and wavelength ranges.

I would seat the diode all the way into the module. Back halfs can often press against the back of fulled pressed diodes.
 

DTR

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Sorry to hear that.. Lets see if we can figure out what happened here. It sounds like nothing had happened yet with it connected to the driver. I am betting the power supply might be the culprit. If you can give some details of the power supply used and the exact process of attempting to power the diodes. I am guessing something was preventing driver from activating the output and nothing had happened to the diode at that point. These are extremely easy to pop on a bench power supply. If a clean supply the exact process I would use is power on the supply. set voltage and current to zero. Connect the diode and then turn the voltage up till it kicks into constant current. Then turn the current up. When done turn current down then voltage down. Disconnect the diode and power down the supply. Even with my nicest BK supply that was $800 used if the voltage is not set to zero when connecting a diode with this low a forward voltage instant LED.

On why the driver was not powering can you make a pic of how it was connected, which would show the specific model and the power source powering it.

I can help ease the pain but lets get to the bottom of what happened.


Hello,


but the DTR back halfs will not touch the back of a full pressed diode. I checked this.

What is more confusing to me is the fact, that the sharp diodes from other seller have 3 pins.



best regards

Edgar
YEa the copper back was designed for the base of the 9mm diodes. On other sizes it is not required to keep the diode thermally stable so they just adds more mass to the module.

That picture is not right on their site. These have a tall can an two pin. Recent batches are serialized printed on the base.

Never rely on third party info to be accurate. There is no verifiable datasheet for this diode publically listing on sharps FTP so only for sure info is on their product catalog page.

Refer to the GH0631IA2GC's terminal connection type which is "9" Then go to the terminal connection section which shows two pin.


LIke the Oclaro variant(which is a three pin) also has an extended tall can.
 
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reloader45

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The driver I used was dead after the first trial. I tested it after that with a dummy load. I connected the diode to a laboratory power supply with the power on to avoid spikes from switching. The voltage looks normal and I could increase the current, but the diode loóks dim like a LED.
I can check the diode tomorrow with an lm317 driver, because i will not risk the other laser driver. But I am sure, this will not change the situation.
It is late in Germany, but I would like to know, why other red sharp diodes have 3 pins?


best regards

Edgar
 

logsquared

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Did you short the output of the driver before connecting the diode? Residual charge in the caps can kill SM diodes real quick.
 

DTR

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With the power on and the voltage and current set to zero? That part is very important with these 638nm type diodes even the 700mW variants. If there is any potential on the supply when connecting it will pop them.

They have all kinds of pinouts if you see sharps page with all the different terminal connections.

Did you short the output of the driver before connecting the diode? Residual charge in the caps can kill SM diodes real quick.
While that is always great advice when first connecting a diver to a diode It does not sound like the driver was turning on at all since there was no light but did see what sounds like an LED output on the power supply with both the diode that was tried with the driver and the one that was not if I understand correctly. Still very limited info though. Will follow up tomorrow and try to get more detail.
 
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paul1598419

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LEDed diodes still work according to the Vf and current, but because of COD they don't lase. I don't see this diode causing a failure of your driver. It was likely damaged in some other way or it was faulty to begin with.
 
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reloader45

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Hello.

it was late last night, so let me resume what happens.

I got a brand new Diode from DTR and a brand new 500 mA laser Driver from x-wossee.

I did not check the laser Driver with a dummy load, because they normaly are adjusted below 100 mA.

So I connected the Driver to the laser Diode. Nothing happenend. I had 4,2 V Input to the Driver, but Zero current. I adjusted the potentiometer of the Driver, nothing happend.

Next, I resoldered the Driver and tried to run the Diode with a laboratory power supply.
Voltage was ok, and then I set the current from 100 mA to 280 mA. The Diode only shows a dim red light below 1mW.
The same with the other Diode.
Later I tested the Driver with a dummy load, no current !

my conclusions:

-the Driver was dead just from the beginning
-Laser diodes do not like laboratory power supply

I have only one question to DTR: Do you test the diodes before you sell them, and if yes, how do you test them?

The threshold of these diodes is quite high. Is it possible to test them without cooling?

my consequences from this waste of money:

I will test every new Driver with a dummy load bevor I use them.

I will test every new Diode with a robust and working LM 317 Driver before i will connect them to a expensive laser Driver.


best regards

Edgar
 

mojo_1234

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Hi Edgar, are you really sure that the driver is/was the problem? These diodes are highly sensitive to ESD e.g. diode pins are not crossed/connected when pressing or soldering leades - diode turns to LED
 




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