Floquet Control of Optomechanical Bistability in Multimode Systems

Cavity optomechanical systems make possible the fine manipulation of mechanical degrees of freedom with light, adding functionality and having broad appeal in photonic technologies. We show that distinct mechanical modes can be exploited with a temporally modulated Floquet drive to steer between distinct steady states induced by changes of cavity radiation pressure. We investigate the additional influence of the thermo-optic nonlinearity on these dynamics and find that it can suppress or amplify the control mechanism in contrast to its often performance-limiting character. Our results provide new techniques for the characterization of thermal properties of optomechanical systems and their control, sensing and computational applications.

Figure 1

(a) Experimental setup including the integrated optomechanical platform with a suspended 2D photonic crystal InP nanomembrane (blue) above a SOI waveguide (red). Inset: SEM micrograph of the L3 defects. (b) Measured transmission spectrum (orange dots) and fit (black line). The electric field distribution associated with each photonic resonance are shown on top. (c) Mechanical spectrum measured by optomechanically probing the photonic mode ($-$) (dark blue) or the mode ($+$) (light blue). The photothermal effect induces different elastic property changes resulting in different frequencies.

Figure 2

Floquet dynamics of a single-mode optomechanical system (a) Schematic of an optomechanical cavity driven with a modulated laser field. (b) Experimentally measured noise spectra centered at the mechanical frequency ${\mathrm{\Omega }}_1=2\pi \times 4.330\mathrm{MHz}$ for $P_{\mathrm{in}}=1.3\mathrm{mW}$ (top) and $P_{\mathrm{in}}=325\mu \mathrm{W}$ (bottom) mapped over the modulation frequency ${\mathrm{\Omega }}_{\text{mod}}$. (c) Theoretically predicted noise spectra for varying ${\mathrm{\Omega }}_{\text{mod}}$ employing high (top) and low (bottom) optical power. (d) Lateral sections along the dotted lines in (b) and (c) of the measured spectra (dotted) and numerical results (solid).

Figure 3

Floquet control of optomechanical bistability. (a) An optomechanically bistable mode is controlled by another nondegenerate control mode with an intensity-modulated pump. (b) The steady state switches when the modulation frequency ${\mathrm{\Omega }}_{\text{mod}}$ matches the control frequency ${\mathrm{\Omega }}_2$ (green) whereas it is unaffected for off-resonant modulation (black). (c) Two-dimensional parameter diagram describing the switching capability of the Floquet drive: the intensity modulation’s phase ${\theta }_0$ aligning with the mechanical phase ${\varphi }_2$ in addition to the frequency matching leads to steady state switching (green).