What Happens When Two Wavelengths Are Modulated at the Same Frequency?

[MS1984]

hi

what would happen if i modulated two wavelengths with the same intensity modulation frequency?

for example if i had 2.0um light and 1.5um light and modulated them both with the same frequency, would sidebands develop around each wavelength? or would they interfer in a more complicated way, giving a more complex sideband structure?

thanks, let me know if you need me to clarify this at all

 

[mikeph]

Unless you have some nonlinear optical effects I don't see how they would interfere at all. The spectra of each individual modulated signal should just add, no?

 

[Baluncore]

If the light is amplitude modulated by a sine wave, then each carrier would have a side band on each side. There would be no interaction between those carriers or their sidebands. That is so long as the modulation frequency was not so high that the sidebands overlapped.

This is the same signal scenario as the AM radio band.

 

[meBigGuy]

for example if i had 2.0um light and 1.5um light and modulated them both with the same frequency, would sidebands develop around each wavelength?

Yes, just like any other amplitude modulated signal.

or would they interfer in a more complicated way, giving a more complex sideband structure?

No, just like any other amplitude modulated signal.

This of course assumes the system is completely linear. The waves cannot interact in a linear system other than interference pattern like effects.