Question

Which wavelengths can be produced when a nonlinear crystal is illuminated with two beams at 500 nm and 800 nm wavelength?

Answer 1

In a non linear crystal, there are different phenomena that can generate light of different frequencies or wavelength

1) harmonic generation

Harmonics are light rays with frquency double or trople or n times the initial frequency.

So, a second harmonic means that the frequency is doubled, or the wvaelength is halved.

A third ahrmonic is 1/3 of the original frequency.

Since we have light of wavelengh 500 nm and 800 nm,

harmonics can be 500/2 = 250 nm, 500/3 = 166.67 nm, 500/4 = 125 nm and so on.

and 800/2 = 400 nm , 800/3 = 266.67 nm, 800/4 = 200 nm and so on.

2) The next one is sum frequency gegeration.

This is the addition of two frequencies of waves.

For wavelength, this is

For the values available,

3) There is frequency difference generation, similar to summing.

Here,

Additionaly, any combination of frequencies that are formed here can get added or subtracted from one another.