Large-amplitude diamond optomechanics by traversing a nonlinear attractor

Abstract

Nonlinear dynamics clamp the amplitude of mechanical resonators driven into self-oscillation by optomechanical backaction. Here we overcome the conventional limits of self-oscillation amplitude by navigating the nonlinear dynamical landscape of a diamond optomechanical cavity supporting coherent optomechanics at room temperature. By exploiting the bistable phase space of the system, we increase the oscillation amplitude by nearly an order of magnitude. This enhancement arises from deterministic access to a high-energy state in the system's nonlinear attractor, and is accompanied by the generation of an optical frequency comb produced by cascaded phonon scattering that underlies the nonlinear dynamics. Our results establish nonlinear attractor engineering as a route to large amplitude coherent phonon generation and provide a platform for optomechanical frequency combs, spin mechanical interfaces in diamond, and precision sensing in ambient conditions.

Figures (4)

• Figure 1: (a) Cavity optomechanical systems. Top: Fabry-Pérot cavity whose mirror oscillations create optical sidebands with amplitude $\alpha_\text{n}$. Bottom: the fiber taper coupled microdisk system studied here. (b) Scattering of the cavity field into sidebands is enhanced when they are on-resonance with the cavity mode. (c) The diamond microdisk's effective potential $U(A)$ as a function of normalized mechanical amplitude and drive laser detuning from resonance. The orange lines trace local minima of $U$. Mechanical bistability is possible in the region between the dotted lines. (d) Effective potential at a fixed detuning, with local minima highlighted. (e) Drive laser transmission for low input power.
• Figure 2: Drive field transmission lineshape for high input power (white line) and corresponding spectrograph of the transmitted probe intensity's power spectral density over the frequency range of the mechanical radial breathing mode, when the drive laser detuning is swept from red to blue (top) and blue to red (bottom). Color scale has units $\text{dB}/\sqrt{\text{Hz}}$.
• Figure 3: Measured (blue) and predicted (red) effect of drive laser detuning on (a) drive laser transmission, (b) self-oscillation amplitude $A$ transduced by the probe laser, (c) mechanical self-oscillation frequency, and (d) signal gain $\eta$ derived from $GA(\Delta)$.
• Figure 4: (a) Optical spectrum of the transmitted drive field for varying detuning. The corresponding average drive field transmission is shown in white. (b) Measured (top) and predicted (bottom) spectra at fixed detunings indicated by dashed lines in (a).