6x diode window is broken - will it live?!

[FireMyLaser]

I ordered a bunch of parts for my portable rgv project now, and I decided to harvest the diode in my 6x sled from glenn. Truth is I have never harvested a 6x sled before, but I think it went pretty well. But when I got the diode out with it's little heat sink I saw that the window was loose. I was like F*** ME GODF*****GDAMNIT!!
But anyways I wouldn't give up, maybe I could save it. I'm not gonna go in detail how, but I managed to never have the diode faceing up so the window couldn't get to the die, get it out of it's little heat sink and carefully remove the can with knife and finally install it in a sure module. I connected the diode to my test driver and slowly turned up the current to 100mA... it wasn't dead (yay).
It seems to be pretty strong at 100mA, I will run it at 180mA ones installed in a heat sink - but will it live on? I know it has been some discussion about blu-ray diodes might get a short lifetime when de-canned, but I have never really been sure about it myself. So if anyone knows from real life experience, what can I expect from my poor diode?
I even bought a fancy 405 super awesome lens for this thing ARG!

 

[daguin]

There are several "open can" violet diodes running out there. The main challenge with this is "stuff" settling on the die. Use a little teflon tape on the threads of your lens to help seal it and leave the lens in to limit exposure to contaminants.

Peace,
dave

 

[FireMyLaser]

That was my plan from the start. Even glue the lens so it wouldn't move for anything, so the three beams always will stay tight. But now I feel like this diode will have a short life no matter what I do, so it's not worth effort to installing in my white fusion kit and secure the whole thing with epoxy...

 

[pullbangdead]

I would avoid glue around it, just because a lot of glues fume. With super glue it's obvious, because it fumes so much that it can't go by unnoticed, but I would be afraid of other glues fuming as well. Maybe that's not a concern and I worry too much about it, but I try to keep glues away from diodes in general.

To be honest, I'm still not buying that the oxidizing environment of normal air is actually causing degradation of the diode. The facet coats are oxides, like SiO2, TiO2, Ta2O5, etc., so I have trouble believing that facet oxidation is really happening without a can on there. What is there to oxidize, the glass that's already 2/3 oxygen when deposited in the first place?

I've read where someone on here posted a theory that the high intensity of light at such a high photon energy (405nm photons have a lot more energy than red photons, of course) can cause organics to break down and deposit crap on a facet or something like that. I've never observed that, I've never read it anywhere else, but I've never seen it disproven either. I can't say for 100% certain that it doesn't happen, but I'm not going to say that it does either. Maybe someone has some more evidence? I haven't personally done any lifetime tests with open cans (it's on my to-do list), but all of our testing is done with lasers still on the wafer, which means no can and in the open air. We don't run them very long for normal tests, so maybe it's just something that takes too long for us to see it in normal tests, but I've never witnessed it.

I know that doesn't totally help you with your predicament. I also know changing a blown diode is difficult in those builds, and so I don't want to make any promises that I can't guarantee. But if it were me, and I had already removed the window carefully and the laser is working and in a module, I'd do exactly like you're saying and forget about it. I personally have a phr with a missing window that's well over a year old now, still kicking. It's very easy for me to chalk up blown diodes with missing windows to the physical damage that is very likely when the window breaks and when removing the can, I don't have any trouble at all blaming any diodes that die like that on physical damage instead of degradation.

So really, I can't guarantee anything, but if it was me: I'd seal the module up with the lens, and forget about it.

 

[FireMyLaser]

Allright, thank you for your input. I'll seal it up and hope for the best. If it dies I will post it, along with the estimated runtime. If the diode was in argon or something like that, wound the environment be like in a can?

 

[pullbangdead]

I honestly don't know what they put in the cans. I seriously doubt it's argon or a noble gas, too expensive. My first guess would be dry nitrogen, but it very well could've been just dry air, or even just regular old cleanroom air (which is typically around 50% humidity).

If you have a nitrogen source, or even just a dry air source, and can blow that into the area while you're putting the lens in, I don't suppose it could hurt to displace regular old dirty air with a clean/dry gas. Not sure how much it would help, but I don't think it would hurt. I wouldn't worry about trying to do it in a glovebox or anything, but can't hurt.

 

[LarryDFW]

Fire My Laser;

Here is the quote from Sharp, who makes Red laser diodes open to the air:

The blue-violet laser beam decomposes air-borne materials because of its short emission wavelength. Thus, when the outer air comes inside the package, the decomposition of materials intensifies, resulting in contamination such as the adhesion of carbon, etc on the semiconductor laser chip and so on. This causes the degradation of light output, which shortens the diode life. Such contamination will not occur in a CAN package, which can maintain airtightness.

Keep a lens assembly with tight threads on the BR diode,
don't use it for burning, and you should be O.K.

LarryDFW

 

[Flaminpyro]

If it's going in your WF you should have no problems at all only the tinyest amount of thread sealer or locktight on the threads will keep them in place and so will teflon tape and it will seal out the air, I like the dry N2 but where you going to find it in a small amounts, if you do let us know.


@ PBD thanks for that technical explain, I liked it !

@ larry thanks for the company info VG !

 

[FireMyLaser]

Thanks a million for the information guys! I was just curious about the gas environment, I don't have access to any of them though.
So pretty much: I seal the module around the lens, threads and at the back of the diode and just let it run. The small amount of trapped air inside the module will decompose and get sterile. And hopefully that small amount of dirt makes no effect on the diode.

 

[FireMyLaser]

All right, *sigh* it is now dead. It died after a short use just after I FINISHED the alignment which took like 5 hours... the diode was completely sealed up but I can tell that a tiny bit of dirt has somehow fallen right in front of the die, which probably killed it. Man this sucks!