We present the fabrication of exceptionally small-radius concave microoptics on fused silica substrates using CO2 laser ablation and subsequent reactive ion etching. The protocol yields on-axis near-Gaussian depressions with a radius of curvature ≲5 μm at shallow depth and low surface roughness of 2 Å. This geometry is appealing for cavity quantum electrodynamics where small mode volumes and low scattering losses are desired. We study the optical performance of the structures within a tunable Fabry-Pérot type microcavity and demonstrate near-coating-limited loss rates () and small focal lengths consistent with their geometrical dimensions.
Fabrication of mirror templates in silica with micron-sized radii of curvature
Daniel Najer, Martina Renggli, Daniel Riedel, Sebastian Starosielec, Richard J. Warburton; Fabrication of mirror templates in silica with micron-sized radii of curvature. Appl. Phys. Lett. 2 January 2017; 110 (1): 011101. https://doi.org/10.1063/1.4973458
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