vivification of 405nm laser diode

[try]

hi,
this post is about vivification of some kind of dead diode.
If your diode emits no light, but there's some voltage drop on it (say 0.7V @ 30mA ), connect it to voltage source 5.0-5.5V (not current-limited) and it will shine back again.

Besides, does somebody has good (or bad) explanation for this?

 

[lasersbee]

If you do not current limit a high current PS and inject
5.5V into a 405nm LD you could possibly LED your Laser
Diode or damage it.
Just the voltage spike produced when hooking the LD to
an unregulated current supply can damage the LD.

I suggest you do a little research and reading about LD
Drivers and why they are used.

Some 405nm LDs will require more than 30mA to Lase.

You should never run a Laser Diode without some type of
current regulation...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[MarioMaster]

He's talking about what we here call "zombie diodes" where after a diode has already been damaged, they can be brought back to life (sort of) by significantly increasing the current to the diode.

My guess is that while the lasing cavity is damaged, it is still there for the most part and significantly increasing the forward current causes the remains of the die to emit significantly more energy than normal which causes the remains of the resonator to function again (albeit poorly)

 

[lasersbee]

Oops.. I missed the "dead diode" in his post.. :yabbem:

Yeah you are right you can sometimes get a dead LD
to put out something by over driving it but the current
to output ratio sucks big time.


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

 

[try]

My guess is that while the lasing cavity is damaged, it is still there for the most part

I do not think that lasing cavity damaged since 1)voltage across diode drops from 5.8V downto 0.7V 2)no light at all were present, not even from LED.
Both symptoms AFAIK can not be connected to cavity damage.

No i cannot damage that particular diode with 5.5V.

 

[Bionic-Badger]

Aren't the end-facets of the resonator cavity catastrophically destroyed when the diode is zombied? So how are you going to cause that diode to lase again by just pumping more power into it? Maybe it'll make the pre-lasing light brighter, but you might as well just use an LED then right?

 

[try]

1. in this particular class of dead diode, laser cavity seems not be destroyed
2. I do not feed more power in it when it alive. It takes 6.5V @80mA normally.
When it dead, it can consume more current at lesser voltage, say 100mA @ 1.2V.
Seems like something inside can grow and short diode circuit, than it can be burned with enough power. Maybe it is tin whiskers, i am not sure.

 

[Bionic-Badger]

Might be interesting to do a macro photo of it to see.

 

[MarioMaster]

It's possible that part of the diode junction melted and created an internal short circuit, increasing the current significantly may have blown out the shorted junction or simply bypassed it due to the chip's own internal resistance at significantly higher current (and temperature leading to higher resistance).

Also, just because the resonator was "catastrophically destroyed" doesn't mean the entire thing was vaporized. Usually the center blows out but perhaps the edges are still reflective enough to lase a bit when sufficiently excited.