574nm 36 mW Yellow Laser

[paul1598419]

I look forward to reading the paper you have in front of you. It sounds like you have this nailed from the information you have given so far. I would expect my example to shift in wavelength and jump as it mode hops........but, it has never done that. It is rock steady at 574nm and ~50 mW. Mine has never exhibited any green light upon activation, nor has it moved on my spectrometer. I am not saying you are wrong......just trying to understand my device.

 

[LSRFAQ]

Two of ours exhibited quick hops to green while warming up. They then mode hopped, and we could watch the yellow climb in wavelength a few nanometers per second until it stabilized. The other started at one yellow wavelength and stayed there. This was observed on a B&W Spectrometer and with an Ocean Optics Spectrometer.
Once warmed up they did not drift much. The other trick is to look at the beam with a high speed photodiode (100 Mhz or so ) and see if it is noisy on an oscilloscope. I have not done that yet.

Steve

 

[paul1598419]

I have watched mine continuously on my spectrometer for as long as 30 minutes now. It starts and stays rock steady at 574nm. I did have a very cheap 532nm laser that did drift up in wavelength as it seemed to warm up. When I reported this I was shot down by a couple members here saying that this was impossible. I also have two multiline 532nm lasers. One does 4 lines and the other, 6.

 

[LSRFAQ]

If it makes you feel better Paul...

ND: YAG THAT I KNOW OF, Off the top of my head with a quick look up.. And there are more with very low gain... But 1064.1 Has far more gain then the rest and generally swamps them by depleting an upper level. BTW, The 1064 nm line bandwidth is about 1.3 nm wide... as is the 972 line.


972
1055.1
1061.5
1064.1
1064.14
1073.8
1074
1080
1088
1105
1116
1123
1318
1338
1414
1444

-----------------------

Steve

 

[paul1598419]

Thanks, Steve. It was you seeing one of these 565nm or 575nm lasers drifting up in wavelength that brought to mind the 532nm one I saw doing the same thing. I can't say why it did this.........just, that it did.

 

[RedCowboy]

If these crystals worked without degrading they would be making lots of them, there is a demand so I can only reasonably assume there is a problem.

Actually I didn't save the email from that reseller who had them, but he pretty much said production problems was the reason he had not received any more yet.

That explains why they had a miss matched driver, someone likely took them out of the trash/bought as salvage and used whatever they could find for a driver.

 

[paul1598419]

Well, I certainly don't want my money back from my purchase of a 575nm one. In total it cost me $65.00, $35.00 of which was shipping. Mine is still rock steady at 50 mW and has not mode hopped once. It doesn't drift nor does it shift and I am still as happy as I was when I received it. I use it at least once a week and if it is going to fail, well, it hasn't given me any indication that it will.

 

[RedCowboy]

I know 532 dpss modules have gotten better over time, but early on some that seemed really stable up and went to pot, but that's a multi issue learning curve the Chinese had to overcome, now this yellow laser single crystal degrading is a shame but in time I hope they work out a solution so future units will have longevity, until then enjoy it while it lasts.

 

[paul1598419]

Well, I got this unit 9 months ago and have used it quite a lot since then. If they are all failing so terribly I would have expected to see some degradation by now. It gets used a lot by me. I had issues with the driver, but have corrected all of those and it has been a great yellow laser for me ever since. Maybe many of these have had issues, but this one doesn't seem to.

 

[aaronnoraa]

Well, I got this unit 9 months ago and have used it quite a lot since then. If they are all failing so terribly I would have expected to see some degradation by now. It gets used a lot by me. I had issues with the driver, but have corrected all of those and it has been a great yellow laser for me ever since. Maybe many of these have had issues, but this one doesn't seem to.

That seems to be a lot more reliable than a decanned NUBM0X and people still buy those and decan them knowing full well what to expect. I wonder if there's something the manufacturer hasn't disclosed other than reliability issues, perhaps sourcing or losing access to a manufacturing plant? It seems odd that they were able to produce examples of a reliable unit and sold them for peanuts, such as the unit Paul purchased, then at some point producing any units at any output suddenly appears to be impossible.

Side question, are these the same crystals that DTR had a sweet image of that had a blue pump diode hitting a slab of crystal and producing yellow output?

 

[paul1598419]

The one DTR had uses a NUBM44 to drive it. These use an IR diode. Somewhere in the 970nm range, IIRC.

 

[LSRFAQ]

After reading paper after paper...
Turns out the dopant metal has a habit of A. Migrating, and B. forming micro-clusters of raw metal in the crystal, and C. forming F Centers of high adsorption. . If your yellow is dying, as in really dead, move the crystal sideways in the laser and retune the pump diode focus and crystal angle. See if it lives. Your pump diode needs to be on wavelength within +/- a nanometer and a half or so, as well for peak power.
The pump diode moves around 0.2 nm /'C . Pump is near 796 nm, although other bands can be used. Wear laser safety glasses when working intracavity, a Watt of pump laser can really damage your eyes.

Steve