800mw Green. Upgrade to 10W pump

blrock · Aug 8, 2011

I've just put my 4-watt-quad-blue-build on hold as I blew one of the 445s this weekend. (Had 4 in series @ 24V 1.2A. The first one in the line LED!)

For a while now I have been toying with the idea of stripping my Lambdapro lab 800mw greenie, rebuilding it and pumping the crystals with some nice 10W+ 808 from my fibre system. I know the fibre system is nicely tuned to 808. A while back I pumped the small crystal from a laser pointer and got some extreemly bright green. Of coarse this only lasted a few seconds after which the crystal caught on fire!

I reason that the crystals in this lab laser could handle a lot more 808nm. Goal being 2W green. Everything is already TEC cooled in the system.

Even if things go wrong and the greenie never works again, it should be a fun project.

Will keep you posted

joeyss · Aug 8, 2011

Woah might want to take it slow. I'd say turn the current upslow from 6 to ten watts while watching the crystals. This will be epic if it works.

HaloBlu · Aug 8, 2011

Certainly a great project!
I've become interested in fiber coupled diodes recently.

Did you build the driver? How difficult is it to cool? Would you have a pics on hand?

Meatball · Aug 8, 2011

Before you go blasting your YAG with 10W, it would be good to know if the fiber output is polarized or not. Also, how well can the fiber output be focused? You will need a thin waist diameter to ensure there is enough power density near the center of the medium.

Cyparagon · Aug 8, 2011

Even if you cool it, they have poor thermal conductivity. You'll probably end up destroying the coatings. Additionally, they can only double so much light.

It's like putting a nitrous oxide system on a moped. Just buy a better bike.

blrock · Aug 8, 2011

HaloBlu said:
Certainly a great project!
I've become interested in fiber coupled diodes recently.
Did you build the driver? How difficult is it to cool? Would you have a pics on hand?

It's a SDL-8110 system:

Sorry. Pic really small

blrock · Aug 8, 2011

Meatball said:
Before you go blasting your YAG with 10W, it would be good to know if the fiber output is polarized or not. Also, how well can the fiber output be focused? You will need a thin waist diameter to ensure there is enough power density near the center of the medium.

Not sure about the polarization...but it can be focused to really small spot

blrock · Aug 9, 2011

So today was the day I stripped my Lambdapro 800mW laser. The laser was only outputting 480mW.

The laser was a nightmare to take apart. Basically everything had been badly cemented together. The ND:YV04 was about 3x4mm. Couldn’t get to the KTP. TOTALLY CEMENTED!!!

After a simple setup(cable ties and thorlab mounts. WORLDS SIMPILIEST 1.2 WATT GREEN LASER

) I pumped a full 10W into the ND:YV04 and got a nice 1.2W. Only about 10% efficient, but it was damn bright. The output dropped very quickly as the crystal heated. Couldn’t see any immediate damage to the crystals visually.

If I find the time I may built it into a unit with some TEC cooling. Better alignment should also improve the output

RIP lambdapro

PS: I also pumped between 1 and 10W into those little 473 modules from EEbay that are floating about. Tek something something. Can’t remember what they called.
I got nothing! Not even a milliwatt 473 

Meatball · Aug 9, 2011

^^Nice work there.

Did you focus the output into each of your Nd:YVO4 setups? Or just the green one?

To get blue out of that B&W Tek setup, you may have to remove the crystal assembly altogether. But I would start with 1W for the 473 system... 10W is way too much!

blrock · Aug 9, 2011

Meatball said:
^^Nice work there.

Did you focus the output into each of your Nd:YVO4 setups? Or just the green one?

To get blue out of that B&W Tek setup, you may have to remove the crystal assembly altogether. But I would start with 1W for the 473 system... 10W is way too much!

I removed the lens from the fiber cable then put the fiber as close to the YV04 as possible.
So as soon as the 808 leaves the fiber is goes straight into the YVO4. It's similar to having the YV04 close to a C-mount 808.

As for the B&W.....I only bought the cystal assemble. It didn't come with the shaping optics,PSU etc. I got just the asemble which is mounted on the TEC.
Do these little guys have OC/HR mirrors? It does look like it. Unlike the green I was playing with which has a coated YVO4. So there are no OC/HR mirrors in the Lambdapro assembly.

LSRFAQ · Aug 10, 2011

Your fiber has a huge NA (Numerical Aperture) which is a positive angle, which will lower the pump density really, really, fast. Its non-linear math, but you can cook up a approximation if you know your fiber core and cladding sizes. You need a simple focusing lens between your fiber and the crystal to get rid of the positive NA and switch to a focused spot.

Steve

rhd · Aug 10, 2011

Do you have any sense as to what the ebay 473s typically run their IR diodes at?

I have a working one sitting here, I wouldn't mind testing the IR output if the diode is accessible. I haven't done much in the way of looking inside of the casing yet.

ARG · Aug 10, 2011

What is the regular pump diode output on a 800mW green?

Meatball · Aug 10, 2011

rhd said:
Do you have any sense as to what the ebay 473s typically run their IR diodes at?

I have a working one sitting here, I wouldn't mind testing the IR output if the diode is accessible. I haven't done much in the way of looking inside of the casing yet.

The current varies with the output sensed by the photo sensor. I believe its gone up to around 2A if you "cut off" the sensor output. I'll try and find my source for this.

ARGLaser said:
What is the regular pump diode output on a 800mW green?

Assuming about 20-25% efficiency, you can count on about 3.5W being there to pump with. If you've got a great green which has been "critically aligned" with a corrected pump beam and with nice OC and HR coatings, it can be tuned down to just above 3W. Count on 4W if the YAG is not critically aligned with the pump source and doubler.

Bluefan · Aug 10, 2011

Pumping a 473nm is more difficult than usual because it's a level 3 laser. The pump will need to overlap the cavity mode. Anything less causes major absorbtion and no lasing, anything more is wasted is used in inefficient higher order modes. A level 3 laser has a much higher threshold, so even with high power a too low intensity means no output, as you found out. Try focussing to a very small spot, with proper alignment I think some blue should be possible.

blrock · Aug 10, 2011

ARGLaser said:
What is the regular pump diode output on a 800mW green?

I was going to measure it(after resoldering the wires) but forgot. I'll do it this weekend and let you know

800mw Green. Upgrade to 10W pump

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