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Direction/Angle for simple YVO4-KTP Crystal

equal

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Hi,

how is your experience with such a crystal module?
Is the alignment important? I think the polarization of the diode is not unimportant. Does anyone know how to align the crystals?

Greetings
 

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Alaskan

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Both LPF and Google are your friend: https://www.rp-photonics.com/vanadate_lasers.html

Vanadate crystals are naturally birefringent, which eliminates thermally induced depolarization loss in high-power lasers. Also, the laser gain is strongly polarization dependent (→ polarization of light); the highest gain is usually achieved for polarization along the c axis. The pump absorption is also strongly polarization-dependent (except at special wavelengths), which can cause problems e.g. when using a fiber-coupled pump source with drifting polarization.

Nd:YVO4 lasers are usually diode-pumped, but can also be lamp-pumped. Compared with Nd:YAG (→ YAG lasers), Nd:YVO4 exhibits a much higher pump absorption and gain (due to the very high absorption and laser cross sections), a broader gain bandwidth (around 1 nm), a much broader wavelength range for pumping (often eliminating the need to stabilize the pump wavelength), a shorter upper-state lifetime (≈ 100 μs for not too high neodymium concentrations), a higher refractive index, a lower thermal conductivity, and birefringence. The consequences of these differences for various modes of laser operation are the following:
  • For continuous-wave operation, Nd:YVO4 allows overall similar performance to Nd:YAG in cases with medium or high power. Whereas the thermal conductivity is worse, the temperature coefficient of the refractive index is smaller, so that thermal lensing is not stronger. Due to its high gain efficiency, Nd:YVO4 is better than Nd:YAG for lasers with very low threshold pump power.
  • Nd:YVO4 is extremely well suited for passively mode-locked lasers with very high pulse repetition rate; nearly 160 GHz have been demonstrated. This feature results mainly from the high laser cross sections and the strong pump absorption.
  • For Q-switched lasers, Nd:YVO4 does not allow for pulse energies as high as for Nd:YAG, because its capability for energy storage is lower than that of Nd:YAG due to the lower upper-state lifetime and the high gain efficiency. On the other hand, Nd:YVO4 is better suited for high pulse repetition rates, where it still allows the generation of fairly short Q-switched pulses.
Compared with Nd:YVO4, Nd:GdVO4 has a similar thermal conductivity, a slightly shorter emission wavelength (1063 nm), a somewhat larger gain bandwidth, lower emission cross sections, and still higher pump absorption. Note, however, that the published data concerning thermal conductivity of vanadate crystals differ considerably, so there are some significant uncertainties.

Pay no attention to the man behind the curtain.... This place ought to be renamed Laser Oz.
 
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kecked

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That reminds me of the video you posted. So just say you don’t want to help me. Hehehe.

All good stuff but I think that was like drinking from a fire hose.

hey do you have safety glasses. Did you read the stickies.


dude eveytwith lasers is not easy nor cheap. Alignment is everything. Sometimes you need to be incredibly precise. If you want to play try finding a dpss laser that’s low power that you can open and tweak to see how stuff works. Casix use to make a crystal with the coatings and all lined up so all you did was add an 808nm diode. This is somewhatinexpensive but rewarding to just see something work.

you can try an 808nm pump diode and a piece of coated nd:yvo4 and play with optics to couple the diode to the crystal and how temperature plays a role. That makes infrared so you need a meter to see it. Then you can add in ktp and play again with temp to see some visible photons. Take it one step at a time and protect your eyes. You’ll really need to do a bunch of reading. You might find a kit for this. Alaskan and the others are amazing sources of reference but you need to learn to crawl first. I mean I’m not going toss crystal symmetry cutting and phase matching nor lensing at you to start. Beam coupling quality. Thermal and electronic effects with upper population inversions. Etc.... you just want to see some photons. I think?

then I could be full of myself too.
 

Alaskan

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Glad you posted that, this is an area of interest for me too. Just that his question was something you could easily find the answer to, but members here are often willing to help regardless because sometimes finding the right search term is the problem, if you can't ask the right question, you cannot find the right answer.
 




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