Electro-Optomechanical Modulation Instability in a Semiconductor Resonator

In semiconductor nano-optomechanical resonators, several forms of light-matter interaction can enrich the canonical radiation pressure coupling of light and mechanical motion and give rise to new dynamical regimes. Here, we observe an electro-optomechanical modulation instability in a gallium arsenide disk resonator. The regime is evidenced by the concomitant formation of regular and dense combs in the radio-frequency and optical spectrums of the resonator associated with a permanent pulsatory dynamics of the mechanical motion and optical intensity. The mutual coupling between light, mechanical oscillations, carriers, and heat, notably through photothermal interactions, stabilizes an extended mechanical comb in the ultrahigh frequency range that can be controlled optically.

Figure 1

GaAs disk optomechanical (self-)oscillators. (a) Electron micrograph of the mesa supporting a row of disk resonators. (b) Illustration of the straight fiber taper evanescently coupled to a disk of the row. (c) Side-view electron micrograph of a single disk. (d) Series of rf spectra showing the transition to optomechanical self-oscillation. (e) Threshold of the optomechanical self-oscillation regime as function of the driving wavelength.

Figure 2

Dual-comb structure in the electro-optomechanical modulation instability regime. (a) Optical spectrum of the light at the output of a GaAs disk resonator driven at large power. (b) Radio-frequency spectrum of the output light under the same conditions.

Figure 3

Evolution of the electro-optomechanical modulation instability radio-frequency spectrum as function of the driving laser wavelength. (a) Experiment. (b) Theory.

Figure 4

Variety of the temporal dynamics met in the electro-optomechanical modulation instability regime. (a) Normalized transmission at the output of the fiber for WGM2, calculated from the model. (b) Time trace of the normalized transmission at the output of the fiber for WGM3, measured experimentally. (c) Mechanical displacement as function of time under same conditions as (a).