A spaceborne mounting method for fixing a 100 × 100 × 100 mm cubic Fabry–Pérot (FP) cavity is presented. The method constrains the FP cavity in eight directions with a titanium bracket, PEEK gaskets, and vacuum glue. Three criteria were proposed for judging whether the FP cavity is offset or not during aerospace vibration tests. Results indicate that the proposed method is a reliable, robust, and stable way to fix a cubic FP cavity in ultra-stable lasers (USLs). This approach paves the way for the use of USLs in space.

Acousto-optic modulators (AOMs) have been widely used in ultra-stable lasers (USLs) for optimizing its performances. A thermal theoretical model of the AOM, which is made by TeO₂, was established. Based on the model, the temperature coefficients of the diffraction angle and efficiency were calculated to be 4.051 μrad/°C and 0.018%/°C. The influences of thermal effects of the AOM on USLs’ cavity coupling and frequency stability were firstly studied. A 1 °C temperature change in the AOM results in a 0.31 Hz frequency fluctuation of the laser within the USL cavity. Simulation and experimental results indicate that, to achieve USLs’ optimal performance, thermal effects of AOMs within the system must be addressed and managed.