CD Laser and KTP

[joblessalex]

Hi, I have been building lasers for a while now but still know very little on IR. I pulled a cd burner diode and was told it was either 790 or 808nm. I put the crystal in front of it and no change in color at all. What is required to get it to work?

 

[DashApple]

Well if its 808nm ( I think it wont be ) , you are still missing the vanadate to generate the 1064nm for the KTP to SHG to 532nm and still you need mounts and they have to be correctly a lined


I think you should start reading online about the DPSS process and IR diodes ..

 

[shokkunlasers]

KTP and LBO or BIBO aren't magical frequency converters

Theoretically you could sum 1/780nm+1/780nm=2/780nm=390nm
but they don't convert any polarization and power efficient

They need high powers to work efficient and those high powers are normally achieved by putting the crystal into the cavity of the laser you want to convert by SHG or using a q-switched laser with high pulse energy.

Both of those won't work with laser diodes
That makes it hard to do
I know that Coherent and others make direct diode doubled lasers
but
1. they are experts and have tools we can't think of
2. they don't use KTP but LBO and more efficient crystals
3. they correct the diodes output to near TEM00
4. they also use at least 1W pump power not a 200mW cd laser diode

 

[joblessalex]

Well that sure ruined my day. I bought a 5mw green pointer and tore it down. It had only 1 crystal in front of the diode, does that mean it was already 1064?
If such a laser is doubled with a single crystal in that laser, what makes 808nm not a 404nm output? Power and efficiency were not a goal, just a color change. I'll have a look at DPSS lasers and see what I can learn. Thanks for pointing me in the right direction!

 

[shokkunlasers]

In cheap laser pointers KTP and YVO4 are glued together that's why it looks like a single crystal

 

[ultimatekaiser]

Yes it's a.bit harder than just putting the crystal in front of the diode. You need to achieve a certain threshold to lase the yvo4, with a good steady focused beam profile (which the diode alone can't usually give), and the polarizations have to match, angle is important, cleanliness of the crystal, (no fingerprints which ruin the coatings or dust) etc. this is high level physics, and not something so easy to do quickly. There's a lot of factors involved.

Also, cd diodes are 780nm. You need a steady 808nm for this process.