# Do sidebands corresponds to real photons at that frequency?

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.

Question:

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

• If you put the beam into a spectrometer what would you see? Are those not real photons? – Jon Custer Oct 18 '19 at 4:05
• What else could they possibly be? – knzhou Dec 28 '19 at 0:36
• 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. – SuperCiocia Dec 28 '19 at 0:42