Re: [DIYbio] Could we use optical heterodyning to boost UV bands into VIS?

I'm not sure exactly what this has to do with biology, but...

Non-linear optical phenomena do in fact exist, but they are hard to achieve.  Under the right conditions (high optical flux, special crystals or absorbent materials), you can get two photons to combine into one.  

The standard 532 nm laser is actually a 1064 nm laser with a frequency-doubling crystal.  Trying to make this relevant to biology, there's a technique called two-photon excitation microscopy which is sometimes a nice way to do fluorescence work.  The excitation source wavelength is far from the fluorescence emission wavelength, so working with fluorescent dyes with short Stokes shifts becomes much easier.  You don't need to design a high-performance optical rejection filter for the excitation source. 

There are other, more complex nonlinear optical phenomena.  Some introductory reading:

On Monday, June 12, 2017 at 6:15:50 PM UTC-7, Nathan McCorkle wrote:

On Jan 9, 2013 11:02 AM, "John Griessen" <> wrote:
On 01/09/2013 12:19 AM, Patrik D'haeseleer wrote:
I suspect his professor meant that the *frequencies* get added and subtracted. Which you achieve by multiplying the signals.

Probably.  That kind of treatment "transforms"  the nonlinear into the linear for ease of calculations.

Hmm, I am still thinking about this sort of thing, and just came across an article that seems to confirm that this sort of technique works/exists... but for some reason (dogma/history/technical-language-barriers??? or something else I'm failing to understand) they don't call it optical heterodyning, but rather 'sum frequency generation':

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