I tried to Google this but couldn't find an answer, so I was hoping the geniuses here might have some knowledge of this.

My very basic understanding of waves is that when they intersect they can can change the amplitude of the resulting wave, but is there a way to intersect them that changes the frequency of the resulting wave?

Reason I ask is I'm ultimately wondering if you could intersect two IR lights (low frequency) and form visible light (at a higher frequency).

Thanks!

no a electromagnetic wave cannot change anothers frequency.

Quote:

Original post by The_Neverending_Loop no a electromagnetic wave cannot change anothers frequency.

While the waves themselves don't change, can't you produce different 'frequencies' by overlaying a number of distinct waves on each other? So the produced frequency is different from the individual waves?

Or was I really asleep when reading about Fourier stuff?

I don't think it's possible to combine two infrared lights to make visible light. In sound (and maybe light too?) you can get beat frequencies when you combine two sounds with similar frequency (the beat frequency turns out to be the difference of the two frequencies) but this presents as a periodic change in amplitude in the original frequency wave, which is not what you want, and is also slower, which is also not what you want.

You can fake all kinds of waveforms (e.g. square waves) by combining series of sine waves, but these all require a series of higher harmonic frequencies (integer multiples of the original frequency).

Offhand I don't see any way of combining low frequency sine waves to approximate one of a higher frequency and my intuition is that it's completely impossible.

You should have a look at the superposition principle. Basically, this tells you that no, you can't, because the frequency spectrum of a superposition of multiple waves is just the sum of the frequency spectrum of the individual waves.

However, that's only true for waves that respect the superposition principle. You might want to have a look at nonlinear optics. In nonlinear media, it is possible to do precisely what you are talking about. However, the article claims that these phenomena are only possible at a very high intensity (such as those provided by a pulsed laser). But they do give an example on the wikipedia page where IR waves are converted to visible light.

In nonlinear optics you are introducing a medium though, which is not the same case of 2 ENM waves acting on eachother. Waves basically just sum their amplitudes

There are some exotic wave properties though that exist but all of them involve something physical, for example in the compton effect (Iam not sure if I spelled it right) the wavelength and hence the frequency of a photon can change as it collides with an electron.

It has been a while since I took my Optics class tho so maybe I might be forgetting something, but as memory serves me waves interacting with dont effect eachother.

[Edited by - The_Neverending_Loop on December 15, 2010 11:31:16 AM]

figure it out, invent holograms, make trillions of dollars.

Seriously no exaggeration. Trillions of dollars.