Enhanced stability from co-resonant cavities in a monolithic array

We demonstrate an array of micro-Fabry-Pérot cavities fabricated through laser ablation on a single fused silica substrate. High-surface-quality mirrors of 100μm diameter produce a cavity finesse of 4745 ± 200 at a cavity length of 533.3μm. This was achieved in a simple array design with 300μm transverse separation. Arrays with up to 12 cavities were simultaneously tested, and absolute frequency measurements correlated strongly with the etched depth as measured by profilometry. Simultaneous measurements of the absolute resonant frequency for neighboring cavities showed a factor of 5 common-mode cavity drift reduction. Arrays of such cavities can be employed in chip-scale cavity QED networks (current cooperativity estimates are at the border of strong coupling for ⁸⁷Rb atoms, C = 1) as well as precise laser stabilization at nearby wavelengths on a chip.