Say I have a carrier laser (optical) frequency $\omega_c$: $E=E_0 e^{i\omega_c t}$.

I propagate it through an electro-optical modulator that modulates the phase by $\beta \sin\Omega t$: $E = E_0 e^{i\omega_c t + i\beta \sin(\Omega t)}$.

If $\beta \ll 1$, the field can be expanded into:

$$ E \propto e^{i\omega_c t} + e^{i(\omega_c+\Omega) t} + e^{i(\omega_c-\Omega) t} , $$

where the new $\omega_c\pm\Omega$ are the sidebands.


The laser emits photons at energy $\hbar\omega_c$. After the modulation, are there actually photons at energies $\hbar(\omega_c\pm\Omega)$?

  • $\begingroup$ If you put the beam into a spectrometer what would you see? Are those not real photons? $\endgroup$ – Jon Custer Oct 18 '19 at 4:05
  • $\begingroup$ What else could they possibly be? $\endgroup$ – knzhou Dec 28 '19 at 0:36
  • $\begingroup$ I am puzzled by second-harmonic generation devices needing a non-linear effect to generate photons of a different frequency from the incident one. An EOM since to be able to do this too easily. $\endgroup$ – SuperCiocia Dec 28 '19 at 0:42

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