From Event: SPIE Nanoscience + Engineering, 2018
We report the development of a phonon laser based on the center-of-mass oscillation of an optically levitated silica nanosphere in a free-space optical dipole trap. A parametric feedback scheme based on the detection of the oscillator’s center-of-mass is used to provide a cooling signal that intrinsically depends on the oscillator’s mean phonon occupation. When an amplification signal is added to the feedback at the mechanical resonance, these two signals produce center-of-mass dynamics that are analogous to those of a single-mode optical laser. Observed phenomena include a threshold in oscillation amplification, a transition from Brownian motion below threshold to coherent oscillation above threshold, reduction in the linewidth of the oscillation spectrum, and gain saturation. We also analyze the statistical phonon number distributions above and below threshold. The observed dynamics are described by a model that includes both stimulated and spontaneous emission of center-of-mass phonons. Importantly, the operation of this phonon laser relies on externally controllable, feedback-based parameters and therefore allows tuning of the threshold via these parameters. We also explore the use of the levitated nanoparticle phonon laser as a detector of weak external forces via injection locking.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert M. Pettit, W. Ge, P. Kumar, Danika R. Luntz-Martin, Justin T. Schultz, Levi P. Neukirch, M. Bhattacharya, and A. Nick Vamivakas, "A levitated nanoparticle phonon laser via feedback control (Conference Presentation)," Proc. SPIE 10723, Optical Trapping and Optical Micromanipulation XV, 107230K (Presented at SPIE Nanoscience + Engineering: August 20, 2018; Published: 17 September 2018); https://doi.org/10.1117/12.2321124.5836015561001.