150mw Bluray Diode : Test to Destruction!

[billg519]

Well, this weekend I decided to finish one of my bluray projects. I had a few of the 150mw bluray diodes from ebay hanging around, so I decided to start by doing a test on one of the diodes. I set up my current regulated bench supply for 0-400ma output. The laser diode was placed in an Aixiz housing fitted with a clear acrylic lens. The rear aperture of the lens holder was opened out to the lens diameter. Power was measured using my Coherent 210 LPM with Coherent 210 Head. Current was started at 40 ma and increased in 10 ma increments up to 300 ma. This was repeated 3 times, and the average of the readings graphed as shown in the attachment below. This diode surprised me by surviving three trips up to 300 ma, including being left on and running at 300 ma for about half an hour when a phone call interrupted me during the test. After concluding this part of the test, I decided to increase current in 10 ma increments past 300 ma until diode failure occurred. Power levelled off, at 300 ma : 206 mw, 310 ma : 210 mw, 320 ma : 212 mw, 330 ma : 215 mw, 340 ma : 218 mw, 350 ma 220 mw, 360 ma : 220 mw, 370 ma = COD ! After failing, this diode still produces a small level of laser power, maybe 3 - 5 mw, but will not increase output anymore. As the Aixiz housing never became very warm, I feel that I did not overheat the diode. Since it still produces minimal output, I feel that I didn't fry the die or any bonding wires. I think that I simply overpowered the coatings on the output facet, leaving only a tiny area functional.

An interesting observation is the two "knee" areas in the graph. One occurs at the 120 to 140 ma range, power stays at 80 mw. The other area of interest was between 220 and 250 ma, where a drop in output from 170 mw to 155mw occurred before output climbed again after 250 ma.

Hopefully my wanton execution of a poor, innocent bluray laser diode will be of some use and interest to the laser experimenter community. At least I put one of these diodes into a host and fed it 190 ma, giving me a nice strong bluray to enjoy. (5th bluray ... Laser Addiction?)

Bill.  (Who now owns one less bluray diode ...)

 

[daguin]

Thanks for continuing the work on these diodes.  And thank you for sacrificing a diode.   A few questions and a comment.  Are you running this CW or pulsed?  Do you know what diode this was?  Was it harvested from a laser sled?  Does it have a square "brand" on the back?  Are there any number/letters stamped or printed on it anywhere?

Also, your output is VERY much out of line with the numerous destructive tests that have been done by members of this forum.  Have you had your LPM calibrated recently?  Is it a thermopile or an optical calorimeter?  If optical what conversion ratio are you using?  From what wavelength are you using the conversion ratio? I and others get a much higher output reading at currents below 200mA than you have reported.  I personally have one running at 300mA that is putting out over 300mW.  I run them at 190mA all the time getting a consistent 175-180mA

You may want to re-check your set-up and run it again (or you have a VERY different diode than we have been using)

Peace,
dave

 

[thesk8nmidget]

i think dave meant 175-180mw

 

[daguin]

i think dave meant 175-180mw

LOL!!! floppy fingers ;D ;D ;D

Thanks

Peace,
dave

 

[billg519]

Hi Dave,

Nice quick reply! This was run CW. The diode did come from a laser sled of some sort. I know that it was not a PHR-803T diode, as the heatsink was made of a different metal alloy. The diode is what is sold on ebay as a 150mw bluray. (UK based seller) I grabbed a few to try them. My Coherent 210 is a thermal type meter. It is new to me, so the only verification on it is a comparison between its readings and my Lasercheck's readings. (I do realize that a Coherent Lasercheck may not give the best results at 405nm) They are close to each other. The diode has a square code mark on the back, no numbers. Case is not grounded. (Like PHR-803T) Hookup is like PHR-803T. I feel that I have a lesser known diode of some sort here. Of course, not having harvested it myself does not let me know anything about where it came from.

I have PHR-803T diodes bought from PSXBOY. The ones I got behave like the graph I have seen on this forum that graphs several diodes. My PHR's follow the output shown in red on the graph I remember seeing. (Red was lowest output, oh well) I know that there are plenty of members here that have received PHR's that are quite strong. Maybe I should order a new batch of PHR's, test one of them to destruction, and post my results of this. A last, less scientific observation of my batch of PSXBOY PHR's, is that not only were they not as strong as say, yours, on the meters, also they don't burn much better than one of my 100mw reds.

This diode that I killed seemed to give me more power than my PHR's did.

Just flipped back and found the graph I referred to above. Zom-B posted it about his PHR test results where he had four PHR's all different. Figures that I would wind up with the weakest PHR's. His graph is found in the thread about HDDVD diodes, page 25 of this thread. The graph below is what Zom-B posted. My PHR's were all topping out at a little over 110 mw. I did not push them further.

 

[photongeek]

Does anyone know if the LD's in Zom-B's graph were from the same batch(lot)? These things are all machine assembled from the same materials. One would think that they would be identical and that the plots would be much closer. Does anyone have an answer to that?

 

[daguin]

Does anyone know if the LD's in Zom-B's graph were from the same batch(lot)? These things are all machine assembled from the same materials. One would think that they would be identical and that the plots would be much closer. Does anyone have an answer to that?

No one here knows what "batches" anything comes from.  All we know is that they are of the same "type."  Microscopic differences in the crystal and other components have a significant affect on output.

Peace,
dave



@ BillG

Do you have or can you take a macro picture of the square code on the back of the diode?  There are members of the forum here that have software to "read" the square code.

 

[GooeyGus]

Can you take a picture of the die of the laser itself with the can removed?? That will give us a big hint in solving this mystery.

Very interesting indeed, bill!!!

 

[billg519]

Dave, I will put the diode corpse under my microscope and get a shot of the code square.

GooeyGus, I will pop the can off the cadaver and get a microscope shot of the die.

Hopefully I can post these photos tomorrow evening.

Thanks for your interest and assistance.

Bill. (Who needs to buy another batch of PHR's and hope for a good one!)

 

[billg519]

Well, I got the microscope out and took a few shots.

First, the code square on the diode. (40x)

 

[billg519]

Here are a few shots of the die.

First, an into the emitter face shot. (40x) A crack can be seen faintly 3/4 of the way to the right.

 

[billg519]

Next, a shot of the top of the die. (40x)

 

[billg519]

Top of the die again. (40x)

 

[billg519]

Top of the die. (100x)

 

[billg519]

Last shot of the top of the die. (40x)

 

[GooeyGus]

The die and diode 'innards' look identical to a PHR-803T. I have a microscope to compare with my 'known' PHR diodes, but I have no way to take a picture of it. It is highly likely that these diodes were used in sleds OTHER than the PHR-803T sled, we just need to find out which ones!

Very cool! Thanks Bill.