Prototype of an ultra-stable optical cavity for space applications

We report the main features and performances of a prototype of an ultra-stable cavity designed and realized by industry for space applications with the aim of space missions. The cavity is a 100 mm long cylinder rigidly held at its midplane by a engineered mechanical interface providing an efficient decoupling from thermal and vibration perturbations. Intensive finite element modeling was performed in order to optimize thermal and vibration sensitivities while getting a high fundamental resonance frequency. The system was designed to be transportable, acceleration tolerant (up to several g) and temperature range compliant [−33°C ; 73°C]. Thermal isolation is ensured by gold coated Aluminum shields inside a stainless steel enclosure for vacuum. The axial vibration sensitivity was evaluated at (4 ± 0.5) × 10−11/(m.s−2), while the transverse one is < 1 × 10−11/(m.s−2). The fractional frequency instability is ≲ 1×10−15 from 0.1 to a few seconds and reaches 5–6×10−16 at 1s.