Silicon microcavity arrays with open access and a finesse of half a million

Abstract

Optical resonators are essential for fundamental science, applications in sensing and metrology, particle cooling, and quantum information processing. Cavities can significantly enhance interactions between light and matter. For many applications they perform this task best if the mode confinement is tight and the photon lifetime is long. Free access to the mode center is important in the design to admit atoms, molecules, nanoparticles, or solids into the light field. Here, we demonstrate how to machine microcavity arrays of extremely high quality in pristine silicon. Etched to an almost perfect parabolic shape with a surface roughness on the level of 2 Å and coated to a finesse exceeding F = 500,000, these new devices can have lengths below 17 µm, confining the photons to 5 µm waists in a mode volume of 88λ 3 . Extending the cavity length to 150 µm, on the order of the radius of curvature, in a symmetric mirror configuration yields a waist smaller than 7 µm, with photon lifetimes exceeding 64 ns. Parallelized cleanroom fabrication delivers an entire microcavity array in a single process. Photolithographic precision furthermore yields alignment structures that result in mechanically robust, pre-aligned, symmetric microcavity arrays, representing a light-matter interface with unprecedented performance.

Mechanical squeezing via unstable dynamics in a microcavity

“…3 for more details). As predicted, the smaller the cavity length the larger the generated squeezing, with S reaching values well over 10 dB for sub-millimeter-sized cavities [48,50,51]. The results shown in Fig.…”

“…(1)]. This regime is within reach for levitated optomechanics [41,42], specifically for an optically levitated nanoparticle coupled via coherent scattering [43][44][45][46][47] to a microcavity [48][49][50][51] in the unresolved sideband regime. Our results are particularly timely due to recent experiments demonstrating groundstate cooling and quantum control of optically levitated nanoparticles in free space [52,53].…”

A photonic platform hosting telecom photon emitters in silicon

“…The scalability, brightness, purity and collection efficiency of these single-photon emitters are key issues in bringing them closer to practical applications. A scalable photonic platform that houses singlephoton emitters integrated into photonic structures such as nanopillars [8], solid immersion lenses [9] or highquality optical microcavities [10] is thus beneficial.…”

Commercializing optomechanical sensors: from the classical to quantum regime

“…To compete, bulky optomechanical experiments must be prototyped and miniaturised. This is now an active research area, where MEMS processes are used to create chip-scale silicon photonic structures on silicon-on-insulator wafers, resulting in sub-milimeter scale Fabry-Perot cavities, 16 evanescent strip waveguides replacing tapered optical fibers, 17 tethered photonic crystal membranes, 18 and suspended strings with ultrahigh mechanical quality factors. 19 The significant size reduction offered by optomechanical MEMS sensors, combined with their ability to reach displacement sensitivities on the order of 10 −18 mHz −1/2 , 7, 20 makes them a particularly disruptive technology.…”