Design of an ultra-compact reference ULE cavity

This article presents the design and the conception of an ultra-compact Fabry-Pérot cavity which will be used to develop an ultra-stable laser. The proposed cavity is composed of a 25 mm long ULE spacer with fused silica mirrors. It leads to an expected fractional frequency stability of 1.5 x 10-15 limited by the thermal noise. The chosen geometry leads to an acceleration relative sensitivity below 10-12 (m s2) for all directions.