Laser Sculpting of Micro-Optical Cavities for Cold-Atom Physics*

Recent developments in milling on fused-silica substrates has enabled the extreme miniaturization of cold-atom technologies via high-finesse Fabry-Perot cavities. Such cavities are useful in a broad range of applications and science where low-emanating, non-destructive coupling to atoms allows in situ observation and manipulation of atomic states. However, previously reported methods suffer from long sample preparation times and a lack of refinement capability, limiting the growth of the field. We present an adaptive optical sculpting method enabling ultra-precise micro-milling of arbitrary surfaces. This method was used to produce spherical mirrors with small radii of curvature and low surface roughness for use in micro Fabry-Perot cavities. We also show application of this adaptive process to produce a variety of surface geometries on both optical fiber tips as well as optical flats. We additionally discuss our capability to apply our iterative milling process to various materials, including to construct GRIN lenses, affording improved mode matching with sufficient finesse for cavity QED applications. The techniques presented will enable access to directly study the quantum dynamics in exotic 1-D Bose gases, 1-D topological edge states accessible in such systems, and novel quantum sensing modalities.