Figure 1: Basic properties of the OM photonic crystal.

(a) SEM micrograph of the fabricated structure. Scale bar, 5 μm. (b) Normalized transmission spectrum recorded for low laser power (<10 μW). Dashed lines indicate the spectral position of the simulated photonic modes. The specific optical resonance under study is highlighted in green. (c) Zoom of the optical resonance under study. Characteristic values of optical quality factor Q_o=2.3 × 10⁴, extrinsic optical decay rate κ_e=1.88 × 10¹⁰ s⁻¹ and intrinsic optical decay rate κ_i=3.58 × 10¹⁰ s⁻¹ have been extracted from fitting the resonance with a Lorentzian function. The simulated y-component of the electric field associated to that mode is also shown (inset). (d) Left axis: RF spectrum obtained by exciting the cavity with the first-order optical mode (black). Right axis: Calculated values of the single-particle OM coupling rate g_o,OM for each of the mechanical eigenmodes are reported with dots. Red and blue dots are associated to in-plane and out-of-plane flexural modes, respectively. Grey dots correspond to torsional and dilatational modes. The deformation profile (u) of the nanobeam associated with the mode with a mechanical eigenfrequency of Ω_m=54 MHz is also shown (inset).