593nm laser question

[Schrecken_Licht]

So, since I now own one of these rather rare yellow/orange laser pointers, I got to wondering exactly how these lasers work in comparison with more common DPSS laser wavelengths. I looked around Sam's Laser FAQ and really didn't see anything (it's late so I didn't have much time to look since you can spend hours going thru all the stuff on that site).

So if 532nm is produced by doubling the output of Nd:YVO, then how do you get the 593nm? That is half of 1186nm, however, I don't know off hand of any laser crystal that produces that wavelength (or of any other laser type). All I know is it is something more complicated and harder to achieve than a 532nm pointer (hence the extreme price and low power).

 

[FrothyChimp]

It's the summation of two wavelengths (1064nm and 1342nm) that resonate within a cavity and frequency doubled. So you get two solid state lasers for the price you pay but the output is only a single wavelength. The difficulty in creating 593.5nm is that the different wavelengths oscillating in the cavity also have different indices of refraction with respect to the HR, OC, YAG/YVO4 rod and the NLO.

 

[Schrecken_Licht]

I would never have guessed that.....I saw something about how yellow lasers work but that was a long time ago and I didn't remember where I saw it. That explains the price one has to pay to get yellow....

 

[Justin]

You can visualize it by thinking that there are two infrared photons created in the diode, which each have a low energy, and these two photons are then annihilated and recombined to form a single photon with a total amount of energy equal to the sum of the energies of the two inital photons. Since higher energy equals shorter wavelength, two long-wavelength photons can combine to produce a single short wavelength photon. I suppose this reaction would also work backwards if you have the right mechanism.

This is a visualization based on the "light-as-particles" way of thinking. You can also describe it in terms of waveforms and frequency summing but it's not as easy to illustrate.

There is an equation somewhere linking photon energy to wavelength but I can't find it at the moment. Anyone?