New high power 405nm diode?

[IgorT]

Thank you again, Kage and Jay, for alerting me about this diode! I hope what you're getting in the mail expresses my gratitude...


As i said, Susie was very cooperative with this little project. She misunderstood my doubts about the diode (i thought it was a harvested PHR), and was genuinelly worried, that the factory she got it from (not her factory) is lying about it. So she offered to split the cost of the sample with me, just in case the results would be bad. (Thank you for that Susie!)


But i asked many questions before paying, she answered them all, and from the story alone, i was sure the diode is real. I asked for it to be factory sealed in ESD bag, and it was - the laser show factory prepared the sample flawlessly. I asked for photos of the packaged sample, before sending PP, and i got that too, and by the time i paid, i had no doubts, this diode would not only be good, but would teach us a lot as well!


We finally have a 405nm diode WITH a datasheet! ;D

 

[IgorT]

Edit: What, No Kink?  :-?

No kink, Kage! And that is no kink up to almost 300mW raw output!!!!

I can't believe it myself!

But the power increase was steady. I did the plot in 5mA increments, and got around 6mW increase every time. No drop of any kind. I need to repeat this range looking for kinks with the visual method, but i don't think there was one...

The tiny jump in power happened, because it suddenly shot over 200mW, i had to switch the range, but i also had to zero-in the meter before that. So i turned the current down, set the meter to 2W range and 0mW, and started again. I guess the diode cooled off a bit in the meanwhile, as the currents i already tested showed a few mW more, so i corrected them, and continued. The corrections start at 170mA, so that's where the power jumps a bit, but it's a straight line after that again.

If i did it in 1mW resolution from the start, it would be a completelly straight line!



EDIT: It's not a virgin anymore, no. In fact by now, it's a dirty whore. No diode should be forced to do what this one just had to...  
Near 300mW raw power!! I don't believe any diode available right now can survive this for very long. I don't want to push it too hard.

I want to compare it to 6x's. So i guess i'll set it to 200mW after plastic. That's still ~250mW raw power. Next i have to plot my old 6x. I hope i can soon plot new ones too..


EDIT 2: Altho it is so tempting to go higher!  :'(
I need to resist!  ;D

The temptation is killing me!

 

[roSSco]

Temptation can be a bitch!

 

[game-genie]

I know you are testing it for only a few hours [?] , but with how many mA should we feed this diode to get an acceptable Lifetime ? Because 250 mW sounds too good to be true :-?

regards
game

 

[IgorT]

Indeed.. ;D


I want to compare it to a 6x, i know the rate at which a 6x degrades at 200mW, but this little monster seems capable of a bit more. But then again, it could be the one and only for a while, or forever. I don't want to just kill it.

If i had one or two more, i'd set it to 220mA and enjoy it while it lasts. But since there is only one, i want to learn as much as possible from it.


Otherwise, as i mentioned at the very beginning, there is always a chance, that the sample would be a random freak. That's why i was hoping for two. Two freaks in a row are less likelly.


But there are always diodes that are different from the majority. Some PHRs have a kink at 100mA, others don't have it till 200mA.. Same with 4x's. I had 4x's with kinks at 80mW, and two with no kink whatsoever as far as i dared test them. Altho one of them died in only seconds at 170mA.. But if i were to continue the plot of the other, theoretically it is possible i would get a graph like this.

Only after testing all 11 i had, did i learn more about them. The 4x's turned out to be quite inconsistent. Soon i'll be plotting 11 6x's (plus an old one on top), and then i will finally know how consistent they are..


I'm sure some 6x's will have a graph not unlike this Nichia diode... That is why i now need to test the beam profile, wavelength, losses in plastics and so on.


Theoretically, this diode could be a really good 6x. Or it could be a completelly new diode.. In any case, i am very glad to have the chance to test it.

 

[IgorT]

I know you are testing it for only a few hours [?] , but with how many mA  should we feed this diode to get an acceptable Lifetime ? Because 250 mW sounds too good to be true  :-?

regards
game

What is "acceptable lifetime" to you? 3-20 hours like a PHR at >150mW? Or do you use your lasers a lot and want at least a hundred hours?


I really don't know at this point. Problem is, i would need to test more of these to learn what they are trully capable off. Like i explained above, there are differences, and this could just be a random freak. But it is those differences, that tell me what they can do on average..

I will soon have a truckload of 6x's to test, and that will tell me more. If this diode is the same as the one used in 6x drives (it could be), then i would say 160-170mW for a decent life (but not "forever" = thousand(s of) hours). 130-140mW if you need reliability (like in a scanner). If you are happy with a shortened life, then up to 200mW. But it will die at 200mW after plastic. Because like i said, no diode available to us so far can survive >250mW raw output. That is above the pulsed ratings of all diodes we know. And when a blu diode is forcing 200mW through a plastic lens, there is over 250mW behind it.


But it will take some accelerated aging tests to find out for sure. But there is no rush. I don't see this diode becoming available in the very near future.


Hmm.. I think i'll set it to 220mW...  :



Otherwise, where did you get 250mW? The diode did a max of 230mW through a plastic lens.
Keep in mind, when i talk about powers, i may talk about three different powers - raw output, power through a 405nm AR coated glass lens (slightly less), and power through an AixiZ lens (much less).

 

[john_lawson]

DROOL

 

[game-genie]

Thx!
One last question:
What does "kink" mean ?

s spoštovanjem! (My slovenish is even worse than my english ^^")
game

Edit: Oh ... I did not read your last post ... Damn i´m to slow...

Acceptable lifetime would be around 40-60 Hours ... But anyway thank you again that you are sharing your results with us ;D

Edit²: Where did I read 250 mW .. I think i have eaten too much today ... Sry :-[

 

[IgorT]

Kink is when you plot a diode, and the straight line suddenly breaks, and the power actually drops, as you increase the current. Then it takes a lot more current to get the diode out of that kink. Inside the kink, the beam is often very distorted, and... Well.. Diodes don't really like being driven in a kink or even above one. They can't survive that for long.


Look for example at the graph of a diode, that was supposed to be a 12x Blu Ray writer diode. The low position of the kink prooved it is a low power HD-DVD READER diode.. Not that we didn't know that before hand (due to Daguin finding identical sleds on ebay). But the graph prooved it beyond the shadow of a doubt. No high power diode would have a kink so low. But a low power diode can be without a kink up to very high powers.


405nm's are strange and bizzare diodes. Where a 405nm has a kink, a 660nm would have a KNEE. The power simply wouldn't increase any further after that. It would almost flatline. Basically, you can't set a 660nm diode above the knee, even if you try.

But due to the 405nm's having only kinks, and increasing the current brings them out of them, we can set them to powers that should be completelly impossible with what is available to us. And then they often live long enough to fool you into thinking they will survive. Then one day you turn them on, and poof.


Look at this 4x diode plot, to see what a kink looks like. If this was a red, the graph would not start going up again after that.

 

[ska8r411]

IgorT,what would you say the lifetime of this laser would be at 230mW?

Looks awesome!

 

[danq]

EDIT 2: Altho it is so tempting to go higher! cry
I need to resist!

Go! Go! Go! Go!
Higher!
Higher!
Higher!
Go! Go! Go! Go! Higher! ;D ;D ;D

 

[game-genie]

Thanks Igor =]

regards game

 

[jayrob]

Wow Igor! Nice work...

The next obvious question is, will you be the 'point man' on a GB for these diodes? :
Jay

 

[IgorT]

Edit: Oh ... I did not read your last post ... Damn i´m to slow...

Acceptable lifetime would be around 40-60 Hours ... But anyway thank you again that you are sharing your results with us  ;D

Edit²: Where did I read 250 mW .. I think i have eaten too much today ... Sry :-[

40-60 hours.. I think that's what a 6x would do at 200mW.... Not 100% sure yet, but i will kill several to find out.

~250mW is the raw output (before the lens), when the power after a plastic lens is 200mW...

 

[IgorT]

Wow Igor! Nice work...

The next obvious question is, will you be the 'point man' on a GB for these diodes? :
Jay

Well, my first turbo GB worked out just fine..  It also wouldn't be impossible, since the tray is tiny and passes our customs safelly... :

If anyone does it, it should be done EXTREMELLY carefully! These would come in a tray, and when packaged, they would be dangerously exposed. In a sled, they are somewhat protected. These should not even be looked at without an ESD bracelett..



But let me do some more testing first. There are many more tests to do! Also, i'll be getting the 6x's in about a week, and i will plot them all, and do some comparisons. If this is the same diode, there is not much point, if we can get them cheaper from sleds. If it is better, on the other hand.....

As i said, this could be the 6x. But theoretically it could also be a freak 4x! Only a torture test will tell us for sure.


But it's such a pretty diode. Just touching it's beautiful long legs feels like sacrilege. Never mind cutting them and soldering to them!
But getting a full tray of them is so tempting..  ;D


I don't know if i will have time for a GB. It's real crazy at work latelly and i have to start the lenses ASAP... We shall see.. Testing first!



EDIT: Oh, i forgot about this. There is only one thing, that bothers me about this diode.. It has a very strong yellow halo! I used to think this is a sign of damage when i first noticed it. After testing all my diodes for it, i found it is present in all of them to some degree. Sometimes it is brighter, other times it is barelly noticable. But it seems to be a common occurance. I write these things down for every diode, in order to see if any patterns emerge. But so far i haven't seen any. I really hope this halo is meaningless, it's just worrying.

Oh, and obviously it would not be present in all of them. I'd expect the occurance to be similar to that with PHRs and such..



Anyway, i decided to set this diode to 220mW.. My 6x was at a similar power and did not die instantly, so.... Here's hoping..

 

[IgorT]

Well i just couldn't go to sleep without turning it into a laser first. I set it to 214mA, where it is doing around 224mW! Need to let it cool off and measure again.... I might lower the current a bit tho.

The beam is definitelly rounder than anything i have ever seen so far! I'd say this diode has the best aspect ratio of all 405nm's. I couldn't really take a good look at it while plotting it, but i still noticed the round shape on the thermopile... Now that i looked at it better, it's simply incredibly round. And fat of course..

At the same time, the "yellow halo" is stronger than ANY i have ever seen! I really hope this doen't mean anything bad.. :-/
Looking against the beam, i can see this strange purple glow coming from the diode, next to the beam. Projected through a filter, it's like two overlapping blobs off to each side of the slow axis of the beam. I have seen it many times before, just never this strong.


Anyway, i don't think it's a 6x anymore. It's similar from some aspects, but also much different. The wavelength is a bit higher than with my 6x, but not as high as some PHRs. This diode might actually be a higher power than a 6x. It's definitelly not lower. The low Vf seems to be a good indicator of this. That is where they are the most similar.


It is a very interesting diode, and there is much more testing to be done.. After catching some sleep, that is..