Install the Nd:YVO4 + KTP ? Distance ? Angle ?

[equal]

hi,

i want to build a green DPSS laser.

i used a 808nm 500mW LD and a "Nd:YVO4+KTP Laser Pumping Crystal".


what is the right way to install the crystal ? What should i consider to get the best efficience ? What is the best crystal working temperature (must i cooling the crystal) ?

Greetings

 

[diachi]

hi,

i want to build a green DPSS laser.

i used a 808nm 500mW LD and a "Nd:YVO4+KTP Laser Pumping Crystal".


what is the right way to install the crystal ? What should i consider to get the best efficience ? What is the best crystal working temperature (must i cooling the crystal) ?

Greetings

You need to have the orientation correct - crystals are polarization sensitive. You may want to install a focusing lens between the diode and crystal set - although it should work without if you can get the crystal close enough.

Temperature depends on the crystal - you will want to mount it to a chunk of metal though - usually with some indium foil in between. Something like this:

Sam's FAQ has an entire section on building simple green DPSS lasers using hybrid crystals - I suggest reading that:

Sam's Laser FAQ - Home-Built Diode Pumped Solid State (DPSS) Laser

You'll also need safety glasses for 532nm/808nm/1064nm before proceeding. 808nm is for all intents and purposes invisible, 1064nm is completely invisible.

Edit:

As you can see - you don't need a focusing lens:

 

[H2Oxide]

What kind of laser are you building? Since you're using a monolithic crystal I'm assuming you want to build a handheld, but if you're planning on building a lab-style laser then there are some other things to take into consideration.

For a handheld, diachi is pretty much spot on. Depending on what diode you're using, you may or may not need corrective optics. If you're willing to de-can your diode and put the crystal set right next to the emitter then you won't need any optics for the pump beam.

As for the temperature, it depends how your crystal was cut and mounted. But it's probably at or slightly above room temperature.

 

[equal]

hi,
THANKS for answering ...

no .. it is not a handheld laser, but the monolithic crystal is the only crystal i have found.
The laser diode is mounted on a tec (peltier) and i play with the settings (current, focus, angle and distance) to get the best values.
I need a reference point to adjust the correct angle for the crystal (90°, 180°, or other ???)

where can i buy payable Nd:YVO4 and KTP ?

Greetings

 

[diachi]

hi,
THANKS for answering ...

no .. it is not a handheld laser, but the monolithic crystal is the only crystal i have found.
The laser diode is mounted on a tec (peltier) and i play with the settings (current, focus, angle and distance) to get the best values.
I need a reference point to adjust the correct angle for the crystal (90°, 180°, or other ???)

where can i buy payable Nd:YVO4 and KTP ?

Greetings

Do you have the crystal set mounted directly to the TEC or do you have it in a chunk of metal that's mounted to a TEC? You'll probably find the best efficiency at around room temperature, maybe a little higher.

May be worth mounting the LD to a TEC too if you haven't - that'll let you tune the wavelength to get better efficiency, assuming it isn't already dead on center.

I'd carefully mark one side of the crystal with a pencil and then use that as a reference relative to the diode/mounting surface.

Payable ND:YVO4 and KTP? Do you mean individual crystals as in not hybrid like what you have?

I've seen this place recommended by a reliable source: Eksma Optics

Other option is to pick up old/surplus crystals from eBay/another member here.

 

[H2Oxide]

I need a reference point to adjust the correct angle for the crystal (90°, 180°, or other ???)

where can i buy payable Nd:YVO4 and KTP ?

Greetings

The crystal set should be parallel to the diode on the pitch and yaw axes. For the roll, it shouldn't really matter, because the KTP is the only polarization sensitive crystal, and it's permanently mounted relative to the Nd:YVO4 at the factory.

Not sure what you mean by "payable", but if you mean separate crystals then Eksma is good option like diachi recommended, and so is Casix.

 

[diachi]

The crystal set should be parallel to the diode on the pitch and yaw axes. For the roll, it shouldn't really matter, because the KTP is the only polarization sensitive crystal, and it's permanently mounted relative to the Nd:YVO4 at the factory.

Not sure what you mean by "payable", but if you mean separate crystals then Eksma is good option like diachi recommended, and so is Casix.

Nd:YVO4 is polarization sensitive too - although it should still work even if you ignore polarization, best efficiency (peak absorption) is achieved when you match the polarization. In the case of hybrid crystals they are cut so that the KTP matches the polarization of the Nd:YVO4 - or should at least be close.

Good suggestion, forgot about Casix!

OP - Keep in mind if you are going for individual Vanadate (Nd:YVO4) and KTP you'll need to ensure the crystals have the appropriate coatings and have the correct cavity mirrors on hand depending on what coatings your crystals have. Mounting the crystals gets more complicated too depending on how you're set up and how much efficiency you are aiming for. You'll need adjustable mounts for any cavity mirrors too.

Relevant section from Sam's FAQ: Sam's Laser FAQ - Home-Built Diode Pumped Solid State (DPSS) Laser

Actually ... that whole DIY DPSS page is worth reading. :wave:

Edit: OP - Wouldn't mind seeing some pictures of what you're working on - if you don't mind that is!

 

[H2Oxide]

Nd:YVO4 is polarization sensitive too - although it should still work even if you ignore polarization, best efficiency (peak absorption) is achieved when you match the polarization. In the case of hybrid crystals they are cut so that the KTP matches the polarization of the Nd:YVO4 - or should at least be close.

Yes, but I doubt OP knows what axis the crystal was cut along, and considering that it probably won't make too much of a difference I decided not to go into it.

 

[diachi]

Yes, but I doubt OP knows what axis the crystal was cut along, and considering that it probably won't make too much of a difference I decided not to go into it.

Yeah, I don't imagine he knows which way it's supposed to be - but figured I'd mention it so that he can try different orientations and hopefully get better efficiency. That's why I said to carefully mark it with a pencil too (ALONG THE SIDE OF COURSE, NOT ON THE CRYSTAL FACES - should have said that earlier in case it wasn't obvious). That way you have a reference point when you're trying different orientations.

But you're right - it should work at any angle on that axis - at least to some extent.