Abstract
We study the mechanical stability of a tunable high-finesse microcavity under ambient conditions and investigate light-induced effects that can both suppress and excite mechanical fluctuations. As an enabling step, we demonstrate the ultra-precise electronic stabilization of a microcavity. We then show that photothermal mirror expansion can provide high-bandwidth feedback and improve cavity stability by almost two orders of magnitude. At high intracavity power, we observe self-oscillations of mechanical resonances of the cavity. We explain the observations by a dynamic photothermal instability, leading to parametric driving of mechanical motion. For an optimized combination of electronic and photothermal stabilization, we achieve a feedback bandwidth of 500 kHz and a noise level of 1.1 × 10-13 m rms.
Highlights
Tunable Fabry-Perot microcavities offer enhanced light-matter interaction in combination with open access and full control of the mirror separation [1,2,3,4,5,6]
We study the mechanical stability of a tunable high-finesse microcavity under ambient conditions and investigate light-induced effects that can both suppress and excite mechanical fluctuations
The design facilitates the introduction of samples into the cavity and enables optimal spectral and spatial overlap between the sample and the optical mode. This is beneficial for a broad range of applications, e.g. in the fields of cavity quantum electrodynamics [2, 4, 6,7,8,9,10,11,12], cavity optomechanics [13,14,15], and cavityenhanced microscopy [16, 17]
Summary
Tunable Fabry-Perot microcavities offer enhanced light-matter interaction in combination with open access and full control of the mirror separation [1,2,3,4,5,6]. If operation under ambient conditions in air is envisaged, the cavity setup will be exposed to acoustic and structureborne noise, as well as thermal drifts and pressure variations. This leads to fluctuations of the relative mirror position and the optical path length, which define the resonance frequency of the piezo v-groove piezo 1/2“ mirror (a) in in in. On timescales of minutes and hours, thermal and mechanical drifts lead to position noise with peak-to-peak amplitudes of several hundred nanometers This is in contrast to the narrow resonance condition of cavities with high finesse F. We discuss the influence of photothermal and radiation pressure effects on the cavity stability and demonstrate a significant improvement of an optimized electronic lock by photothermal self-stabilization
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