Does the ruby laser (the first invented laser) have nonlinear behavior?

[Sciencestd]

Hello Everyone!

I read about the function of the ruby laser which made from ruby crystal and has three energy levels. There is radiationless transition to what so called metastable level and then the electrons there stimulated to transit to ground energy state. The question is: does this process considered as nonlinear optics? does ruby laser has nonlinear optics concept? One of what also confused me that when I read in a book that the nonlinear optics born was in 1961 after the invention of the first laser (ruby laser), and there they could get second harmonic generation... So please if you can explain these things tom me I will be glad for that known that I'm bit new in this field. Thank you!

 

[shjacks45]

Not sure what you are looking for with "non-linear". Like most lasers, a minimum number of phosphor in the exited state before a laser discharge can occur. Others like He-Ne lasers keep enough molecules in the exited state to discharge continously. Perhaps a threshold for emission is your non-linear.
True non-linear optics, like Lithium Iodate, can mix two light frequencies and get a third light frequency. Or it can double or tripple single frequencies e.g. turn an infrared laser beam into a blue laser beam.

 

[shjacks45]

Not sure what you are looking for with "non-linear". Like most lasers, a minimum number of phosphor in the exited state before a laser discharge can occur. Others like He-Ne lasers keep enough molecules in the exited state to discharge continously. Perhaps a threshold for emission is your non-linear.
True non-linear optics, like Lithium Iodate, can mix two light frequencies and get a third light frequency. Or it can double or tripple single frequencies e.g. turn an infrared laser beam into a blue laser beam.

I used "phosphor" to simplify atomic emission (chrome in ruby), emission from organic dye molecules, emission from charge anhiliation in semiconductors (bandgap laser).

 

[tech99]

For harmonic generation I think you need a coherent oscillator like a laser. Before the invention of the laser, we had neon tubes, for example, which just created incoherent optical noise. A parallel to this is the radio frequency oscillator, which has harmonics, and the spark gap, which does not.

 

[DaveE]

Ruby is non-linear, to some extent. You can find the data with a web search. However, non-linear optical materials isn't a beginner level of physics.

In practice, it isn't used as a non-linear material in optical design since there are much, much more efficient nonlinear crystals (KDP, KTP, LBO, BBO, etc.). It may be of interest if you want to design a modern Ruby laser (which I don't think anyone does these days); it would come into play as a lossy element in the gain medium. Except for some CW lasers, frequency doubling (or mixing) is typically done outside of the laser resonator to avoid the loss issues with non-linear optics from interfering with the laser gain. There are typically fewer constraints on the non-linear crystals when they don't have to be inside the laser resonator.

I suspect that what they meant was that Ruby lasers were a light source that allowed evaluation of non-linear behavior in other materials. Ruby was one of the early sources of pulsed high peak power laser light, which you want if your looking for non-linear behavior.

 

[Sciencestd]

Thank you all for the answers, it directed me and explained a lot of things to me. :)
Sure if I have further questions so I will post it here ;)