Figure 25.1 — Cavity optomechanics Figure 25.1 — Cavity optomechanics. (a) An example of an optomechanical system is a cavity formed by a fixed mirror and a moving mirror and pumped by an incident field: a small displacement of the moving mirror changes the electromagnetic field present in the cavity and the field feeds back through its radiation force on the mirror position. (b) The mechanical oscillator modulates the pumping light (ω), producing two sidebands (the Stokes sideband ω – Ωmass and the anti-Stokes sideband ω + Ωmass). As shown in the picture, when the input field is detuned on the red side of one of the cavity resonances (dashed line), the anti-Stokes sideband gets enhanced and, because anti-Stokes photons have more energy than the pumping field’s ones, energy is extracted from the mechanical oscillator into the cavity field (optical cooling). For blue detuning, the Stokes sideband is enhanced and, thus, energy is transferred from the field to the mechanical oscillator (optical amplification, not shown).