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Originally Posted by
akmetal
Is there a book that has an exhaustive list of all materials that have been used for laser experiments and gives the primary frequency generated from said material (crystals, gases, everything)
There are likely several books on the subject. Google is your friend. Here's a good starting point. A member here has also produced an app that had a pretty comprehensive list of lasing lines, but I can't find a link to it anymore. (Laser Line software - anyone remember this?)
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is there any academic material on say why CO2 produces 10,000 nm and ND YAG produces 1,100 nm.
Short answer: Quantum Mechanics.
More in-depth answer: it's a result of the difference in energy between specific electron excitation states. Different molecules have different "allowed" energy states for their bound electrons. Find a substance that has a pair of meta-stable states corresponding to the wavelength you want and you're on the path. (Note: this is *hard*.)
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Why are crystal lasers more powerful and could gas lasers be just as powerful with the proper cooling and gas circulation?
There is no hard and fast rule about which laser type is more powerful. *Some* crystal lasers are more powerful for a given application, while in other applications gas lasers are better. Some gas lasers are incredibly powerful. (Look into gas-dynamic lasers, deuterium-fluoride lasers, and chemical oxygen iodine lasers.) Likewise, there are massively powerful crystal lasers. (Shiva/Nova comes to mind.) For a given wavelength and operation mode (continuous vs pulsed) you can say that one technology is superior to the other. Change one of the variables, however, and you'll get a different "best" answer.
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I need ~ 1,100 nm but the only laser I could find that will produce primarily in that frequency is a ND YAG laser which is a crystal laser. Does a gas laser exist that produces this frequency, I would think out of all the gasses known to man there would have to be a gas that produces ~ 1,100 nm
There may be several gases that can be made to lase at ~ 1100 nm, but other than the COIL technology mentioned above (hideously expensive, very complicated, and toxic to boot), I'm not aware of one off the top of my head.
More importantly though, this is something that has been researched to death already, and for that specific wavelength range the current "best solution" is YAG, unless you have the resources of a nation-state and want to experiment with the aforementioned chemical oxygen iodine laser. I should point out that this is a bit of a fools errand, however, as the US Government spent over $5 billion developing the COIL (and the modified 747 to carry and power it) before eventually deciding that the technology was a dead end. They are now focusing on YAG and direct diode solutions for output in this wavelength range.
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YAG is a synthetic crystal which means that someone deliberately created this stone for lasers ... how did they know they would need yttrium aluminum garnet and how did they know to dope it with Neodymium?
See above answer about electron energy levels. And if you really want to get deep into it, you're looking at a *bunch* of 400-level (and up) college physics classes to understand the quantum mechanical math behind it. (For the record, I gave up long ago.) Suffice to say that in the early years of lasers (1960's-1980's) the research involved a lot of trial and error. But now with a ton of math (and computers to help), they're getting better about predicting materials that will work for a desired wavelength. And even so, they still struggle. (Look at how long it took to get direct-injection green diodes, for example.)
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Originally Posted by
akmetal
It would still be cool to know the thought process of some one sitting there one day saying ... hey im going to create synethic yittrium aluminum garnet and dope it with neodymium.
Also why use diode lasers to pump it, why not use a CO2 laser to pump the ND YAG laser?
Again, back to Quantum Mechanics and those electron energy levels. To pump (excite) the electrons to high energy levels you need to use a wavelength that is very close to the energy needed for the jump. Long wavelength = small jumps, short wavelength = larger jumps.
If you tried to pump YAG with the output of a CO2 laser you wouldn't be able to achieve a population inversion because you wouldn't be exciting the electrons to the metastable level from which they fall to emit 1064 nm light. At best you'd just heat up the YAG rod.
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Perhaps once I have read through the material I will slowly develop the intuition to develop my own gas or crystal.
Perhaps.
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Originally Posted by
mixedgas
Do you really think if there was a high power gas laser with efficiency better then Co2 and not requiring Deuterium Fluoride or superheated Chlorine,Oxygen, Bromine and dense Iodine vapor moving while burning through a perfectly optically clear laminar flow at upwards of Mach 2.5, that it would not be in production?
HAHA! I had totally forgotten about the flow dynamics of the COIL laser, to say nothing of the H-F / D-F lasers. Excellent point Steve! You know, the more I read about the work on the YAL-1, the more in awe I am at the entire effort. You really have to give them credit for getting the damned thing to lase in the first place, let alone keeping it running inside a plane flying all over the place. Alignment alone had to be a cast-iron bitch! (Airplanes tend to be rather flexible, after all...)
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If there were such a way to make a cheap beast like that my former employer would gladly license it.
Assuming the military didn't grab it first! They'd kill for something like that...
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Originally Posted by
akmetal
That is a very good point. Yea i read about the bromine lasers and they seemed nasty and I dont have any desire to circulate nasty poisen through a cooling system.
Copper Bromide lasers are child's play compared to the lasers Steve was talking about. Seriously, do some reading about the COIL-based YAL-1. If that doesn't give you pause, nothing will.
As for your final comment about the Wright Brothers, remember that the only ones who told them human flight was "impossible" were the uneducated. There were ample examples in nature (birds) that showed it was entirely possible, plus the world already had lighter-than-air vehicles. Most scientists knew it was only a matter of time before someone solved the heaver-than-air problem. The true challenge was *controlled* flight, and that is honestly their biggest innovation. Apart from that it was just some engineering and finding a lightweight engine that made enough power.
In this case, while the laws of physics don't explicitly prevent what you're looking for, a great number of people have spent a lot of time looking, and the consensus is that, for near IR wavelengths, gas lasers are inferior to YAG and direct diode technologies. But even with that caveat, it's still conceivable that they missed something. Still, the Wright Brothers had it easy by comparison.
Adam
