Characterization of an ultra-stable optical cavity developed in the industry for space applications

We report the main characteristics and performances of the first - to our knowledge - prototype of an ultra-stable cavity designed and produced by industry with the aim of space missions. Finite element modeling was performed in order to minimize thermal and vibration sensitivities. The system was designed to be transportable, acceleration tolerant (up to several g) and temperature range compatible (ΔT ~ 40 K). The optical axis of the 100 mm long cavity is vertical. The spacer is made from Ultra-Low Expansion (ULE) glass and mirrors substrate from fused silica to reduce the thermal noise limit to 4×10^-16. The axial vibration sensitivity was evaluated at (4 ± 0.5) ×10^-11 /(ms^-2), while the transverse one is <; 1×10^-11 /(ms^-2). The fractional frequency instability is ~ 1×10^-15 from 0.1 to few seconds.