Abstract: A monolithic photonic resonator includes a bulk optic with first and second superpolished facets, and a high-reflectivity coating applied to each of the first and second superpolished facets. The superpolished facets form an optical resonator. The bulk optic is a single piece of an optical material that is solid, i.e., has no internal holes, gaps, or pockets. The bulk optic therefore serves as an intraresonator optical medium while still supporting a finesse of 10,000 or more. The superpolished facets may be counterfacing to form a Fabry-Perot cavity. Alternatively, the bulk optic may include forms one or more additional facets off of which light inside the bulk optic undergoes total internal reflection. The monolithic photonic resonator may be mounted in a support structure that minimizes the overall vibration sensitivity of the resonator's resonance frequency.