Relative frequency stability among separate Fabry-Perot cavities on a shared glass substrate

Many atomic, molecular, and quantum optics experiments require various disparate, yet precise, laser wavelengths that must be stable over long periods of time. High finesse Fabry-Perot optical cavities are an oftentimes cheap and reliable source of stability for laser systems. We report on the performance of a passive optical cavity reference system consisting of a single Ultra-low-expansion glass spacer with four cavity bores, where each cavity mirror pair is broadband coated to cover a separate range of wavelengths. In total, the four-bore cavity has a finesse of greater than 47,000 from wavelengths 390 nm - 1.75 μm. Using the Pound-Drever-Hall method to lock our lasers we measure the Allan variance of the differential noise between relative bores. We show the temperature dependence of the frequency instability and give evidence that the dominant source of instability is the bonding between the spacer and mirror substrates.