Infrared light wavelength divider, feasible?

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neazoi

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HEllo, this is more like a physics question, but I did not know where to ask, so hopefully some of you may have any hints.

Is that possible (and how) to divide the light wavelength of an IR source to produce mm wave microwaves?

One way I was thinking, could be the use of a substance. Similar to the phosphor, which absorbs UV light and emits lower wavelength green light, a suitable substance for IR could exist?
 

At optical frequencies, the process is referred to as "parametric downconversion" whereby a higher energy (higher frequency [shorter wavelength] = higher energy) photon is 'converted' to two lower energy photons in a non-linear optical medium.

The challenge is finding a medium/material that exhibits sufficient non-linearity for the wavelength in question (and available power) to make the pitiful efficiencies of the process tolerable. For near-IR/visible wavelengths, crystalline samples of weird substances like lithium/potassium niobate/tantalate are often used. For the mm wavelengths though, I wouldn't have a clue! Something about nitrogen vacancies and quantum dots rings a bell of familiarity but I can't recall having heard of anything practical - but my experience in the field is nearly 10 years old... (so undoubtedly there's now a funky metamaterial available that might do the trick

Sounds fascinating!
 
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    neazoi

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Thanks very much for the info, this is a kickstast to see what is going on in this field!

Practically, this could lead to easy production of mm wave frequencies using cheap power IR diodes as sources. Provided that the cost of this "substance" will be low enough the whole system would cost way too less than a mm gunn device or multiplier. (at least that is what I have thought)

Then why not using an IR laser to produce laser in the mm frequencies instead of using the big and bulky free electron laser? However this "substance" may well decohere the laser, so this could be of no use.

These are just ideas that come into my mind, thanks for helping!
 



To my knowledge so far nobody invented an "IR divider". Terahertz and high mm-wave signals are either generated by multiplication of a lower frequency, or, by beating two IR or light signals in a nonlinear element.
Both methods are state of the art now, and both generate a lot of noise which limits the use of mm-wave and GHz devices.
Frequency dividers that are commercially available can operate up to ~50 GHz; their principle is a lock-in oscillator, so the input signal power must be within a window.
You have an opportunity to go into the problem and try to invent a novel way of generating mm-wave and THz signals with a better noise output.
 
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    neazoi

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One of the problems with a divider is that the photon energy drops as the wavelength increases, so you end up dumping a lot of energy in the divider.

Daft thought:
Intracavity Stokes shift a near IR laser followed by mixing the direct and stokes shifted beams in a non linear crystal?
Phase matching the non linear element at the differene frequency would be interesting and the walk off angle would probably be extreme.

Phase noise would be horrible, even with some kind of intra cavity etalon, but phase noise in THz sources is always horrible.
 
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    neazoi

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