New high power 405nm diode?

CRFultz said:

I have enough 6x's on the way to test their life at 200mW

Are these the one's were waiting for?

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Yes, these are the one's we are waiting for..

I've been waiting for them for nearly two months now, cos i need them to kickstart the lens GB, but instead i got one dissapointment after another. So i took matters into my own hands, and now they are on their way to me with USPS Express..

CRFultz said:

How long will the testing take?

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How long the testing will take... Well, it takes as long as the diodes need to die, so the longer it takes, the better.

But from the one 6x i've had for many months now, i am already pretty sure, they can last for a while even at 200mW through plastic lens. It's just the "how long" i want to find out - in hours. That will then tell me how long they will last in the hands of an average user.

For now my estimates (160-170mW after plastics for longevity) may be considered a bit conservative (altho in reality even this is already an absurd power and it's a miracle they can take it), but the testing might just make me more comfortable at setting them a bit higher.

hydrogenman15 said:

Didn't you say that hot diodes could last longer then cold diodes? The 6x got less efficient over time and is it possible that might actually help it? <-- I'm not so sure about that but i thought I might ask you.

--hydro15

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No, i said hot diodes can survive higher currents, than cold diodes. Because it's their output power that causes damage to them, and a hot diode puts out less power, so it's under less stress from this side, but on the other hand, it can then age faster. Especially, if it is driven at constant power, so when it's hot, the APC driver drives it harder to reach the same power. But that scenario is not applicable in our case.

If you had two diodes one more, the other less efficient, and would set them to the same current, the less efficient one would put out less power, and would be under a lower overall strain. But i set these two to the same power, not the same current.

Also, my 6x being less efficient than before has is a result of degradation. If i would have left the current the same, the dropping efficiency would mean less power, reducing the strain on one end, but at the same time, the dropping efficiency is a result of damage accumulating, so while it would be under less stress on average, it already has "cracks", which are spreading.


But i raised the current. I pushed it higher than ever before now. And yet it would seem to be holding up better. But at this point, i don't yet know anything for sure. I set the Nichia to 200mW, and i'm killing it now. Later i will compare the results to a 6x of the same efficiency. My old 6x i will leave where it is, just to see what happens.


A few posts back i explained that theoretically, a lower efficiency diode might survive longer, than a high efficiency diode. But i meant a new lower efficiency diode, not a diode that has a lower efficiency, cos it's half dead.

IgorT said:

[quote author=hydrogenman15 link=1228867955/140#159 date=1230480243]Didn't you say that hot diodes could last longer then cold diodes? The 6x got less efficient over time and is it possible that might actually help it? <-- I'm not so sure about that but i thought I might ask you.

--hydro15

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No, i said hot diodes can survive higher currents, than cold diodes. Because it's their output power that causes damage to them, and a hot diode puts out less power, so it's under less stress from this side, but on the other hand, it can then age faster. Especially, if it is driven at constant power, so when it's hot, the APC driver drives it harder to reach the same power. But that scenario is not applicable in our case.

If you had two diodes one more, the other less efficient, and would set them to the same current, the less efficient one would put out less power, and would be under a lower overall strain. But i set these two to the same power, not the same current.

Also, my 6x being less efficient than before has is a result of degradation. If i would have left the current the same, the dropping efficiency would mean less power, reducing the strain on one end, but at the same time, the dropping efficiency is a result of damage accumulating, so while it would be under less stress on average, it already has "cracks", which are spreading.


But i raised the current. I pushed it higher than ever before now. And yet it would seem to be holding up better. But at this point, i don't yet know anything for sure. I set the Nichia to 200mW, and i'm killing it now. Later i will compare the results to a 6x of the same efficiency. My old 6x i will leave where it is, just to see what happens.


A few posts back i explained that theoretically, a lower efficiency diode might survive longer, than a high efficiency diode. But i meant a new lower efficiency diode, not a diode that has a lower efficiency, cos it's half dead.[/quote]

Ok thanks, I was just wondering.

Ok, old degraded 6x still holding up at 260mW after medium custom lens. Nichia still fine at 200mW after plastics. There probably is some degradation going on, but so far it is too soon to tell. Now that i think of it, setting it to 199mW would have given me 10 times the resolution, and wouldn't really influence the testing. But if i keep changing the power it will be hard to keep track of degradation...


I also got my new 6x's in just now, so the testing begins...

Hey Igor, I am looking to start my own testing of 6x diode. At this point I think the more we gather and compare reports, the faster people will want it and GBs are going to move along faster and cheaper.

So GGW-H20L is the only confirmed sled with this diode? Is there quick way to get one shipped for testing ? I am talking to one guy to look for under $60 supply in small amounts hopefully.

best regards

Miloš

I will put some of my 6x's on a cycler circuit, and keeep them running (ON for 5 minutes / OFF for 5 minutes to simulate normal use and add the power up/down related stresses) till they die at different powers. The beam will hit a photo transistor, which will turn on a time recorder. That way i can just leave them run, and when they die, the beam won't come out, and won't toggle the time recorder anymore..

So when i see a diode is dead, i just disconnect the time recorder, put it on a reader, and it tells me how long the diode has survived that particular power. I did that with PHRs, but PHRs are cheap. With 6x's on the other hand, this becomes an expensive experiment, so i have to choose the test powers wiselly.


The GGW-H20L is the only sled with this diode, yea... I can get them at a decent price, but there is a minimum order quantity.. Other than that, they will be available in various GBs. The few that are in circulation now all came from a small off forum turbo buy that i did with a small number of participants all pitching in big time (we had to buy 200 PHRs on top, just to get our hands on a few 6x's).


Umm.. Miloš, drop me a PM...

Miloš said:

Hey Igor, I am looking to start my own testing of 6x diode. At this point I think the more we gather and compare reports, the faster people will want it and GBs are going to move along faster and cheaper.

So GGW-H20L is the only confirmed sled with this diode? Is there quick way to get one shipped for testing ? I am talking to one guy to look for under $60 supply in small amounts hopefully.

best regards

Miloš

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I don't think the diode on this thread is in a GGW-H20L, but i'm not sure. I don't think we have found it in a sled yet. I think Igor was just comparing them

robjdixon said:

[quote author=Miloš link=1228867955/160#164 date=1230667240]Hey Igor, I am looking to start my own testing of 6x diode. At this point I think the more we gather and compare reports, the faster people will want it and GBs are going to move along faster and cheaper.

So GGW-H20L is the only confirmed sled with this diode? Is there quick way to get one shipped for testing ? I am talking to one guy to look for under $60 supply in small amounts hopefully.

best regards

Miloš

Click to expand...

I don't think the diode on this thread is in a GGW-H20L, but i'm not sure. I don't think we have found it in a sled yet. I think Igor was just comparing them
[/quote]

Oh, i thought Miloš was asking about the 6x diode - if the GGW is the only sled with the 6x diode. A minute before that i was replying to him in DanQ's testing thread, and i confused the two threads..


Were you asking about the 100mW Nichia or the 6x, Miloš?

The Nichia is not in any sleds we know of. It could be, it would probably work in a 6x writer, but it's a completelly new diode. Not the same as 6x, even tho the electrical characteristics are nearly identical. But the beam profile isn't.

IgorT said:

[quote author=robjdixon link=1228867955/160#166 date=1230716776][quote author=Miloš link=1228867955/160#164 date=1230667240]Hey Igor, I am looking to start my own testing of 6x diode. At this point I think the more we gather and compare reports, the faster people will want it and GBs are going to move along faster and cheaper.

So GGW-H20L is the only confirmed sled with this diode? Is there quick way to get one shipped for testing ? I am talking to one guy to look for under $60 supply in small amounts hopefully.

best regards

Miloš

Click to expand...

I don't think the diode on this thread is in a GGW-H20L, but i'm not sure. I don't think we have found it in a sled yet. I think Igor was just comparing them
[/quote]

Oh, i thought Miloš was asking about the 6x diode - if the GGW is the only sled with the 6x diode. A minute before that i was replying to him in DanQ's testing thread, and i confused the two threads..


Were you asking about the 100mW Nichia or the 6x, Miloš?

The Nichia is not in any sleds we know of. It could be, it would probably work in a 6x writer, but it's a completely new diode. Not the same as 6x, even tho the electrical characteristics are nearly identical. But the beam profile isn't.[/quote]

I was indeed asking about 6x diodes where we are starting to get GBs and slowly our hands on. Not Nichia. Although Nichia according to spec sheet is certainly something extra to look forward to. I like spec sheets where a lot of our speculation is answered and we don't have to waste time and money in order to realize its limits and potencial.

sorry for confusion.

Sorry to confuse guys! I asked this question in wrong thread.

So when are we going to do a GB on these new nichia diodes?

Igor;

This was from an article on 400mw continuous power 405nm laser diodes:

"Unfortunately, it is very difficult to address these weaknesses with a conventional ridge-waveguide laser design , which can only maintain single mode emission at low output powers.

Above an output power that is referred to as the kink level, emission switches to a higher order mode that is incompatible with the focusing optics used to read from, and write to, the disc."

It mentions the "kink" and changes in focus.

LarryDFW

Which sounds like it could be measured or demonstrated with a transmissive diffraction grating.

Do you have one handy, Igor, or shall I send you one?

(Incidentally, the magic diode has been magically disappeared by the maid, who is obsessive about vacuum cleaning. I will try to find a new one, now that I've given her a brief tour of the wide range of toxic powders on my workbench that will go straight through the vacuum cleaner and into the air she's breathing while working. She has been very careful to avoid my workbench after that, so the next one should be safe. It's not the only diode to suffer a terrible fate before I told her that, I'm afraid.)

LarryDFW said:

Above an output power that is referred to as the kink level, emission switches to a higher order mode that is incompatible with the focusing optics used to read from, and write to, the disc."

It mentions the "kink" and changes in focus.

LarryDFW

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Yeah, i know what happens in a kink. The spot starts splitting into two, basically a larger area that moves to the "left" and a smaller that moves to the "right". It's somewhat similar to mode hopping, this is easiest to observe with PHRs or 4x's, or the so called 12x, where it was really bad. There, half the spot simply went missing.

The reason it mentions focus is, that if the diode was in a kink at the power where it should burn holes in the disk, the holes could be imperfect and the written data could be ruined, since a deformed spot wouldn't focus into the same tiny area as it normally would..


But the weird thing is, i can't find a kink in 6x's or in the Nichia at "survivable" powers. A PHR can be set above a kink and live for a number of hours. Sometimes long enough to convince you it's gonna urvive.

But DanQ plotted a 6x up to 300mA, where it did 295mW after a plastic lens, and i didn't see a kink in the graph... Unless it was skipped, but i think it should still be noticable.. I fear i will need to kill a 6x, just to see if they have a kink or not. But the strangee thing is, they definitelly do NOT have it anywhere close to their pulsed power rating, not even 100mW above it..

suiraM said:

Which sounds like it could be measured or demonstrated with a transmissive diffraction grating.

Do you have one handy, Igor, or shall I send you one?

(Incidentally, the magic diode has been magically disappeared by the maid, who is obsessive about vacuum cleaning. I will try to find a new one, now that I've given her a brief tour of the wide range of toxic powders on my workbench that will go straight through the vacuum cleaner and into the air she's breathing while working. She has been very careful to avoid my workbench after that, so the next one should be safe. It's not the only diode to suffer a terrible fate before I told her that, I'm afraid.)

Click to expand...

It's actually very easy to spot a kink visually, even if you don't do a full plot. No diffraction grating necessary. An enlarged spot on the wall shows it, i can even see it in a parallel beam, either when shining it through a yellow filter, or with smoke..

Unless the kinks are much less pronounced with the higher power diodes? Hmm..

A higher power diode may be able to sustain more modes in the cavity than a lower power one (free spectral range), so you may see a more smooth jump with a high power diode, I guess. Essentially, a closely spaced set of modes may resemble a broad single mode, while a few sparse modes may appear fully distinct.

Worth a thought, though.

this discussion arouses me! it's like laser Pron..