Compact, Portable, Thermal-Noise-Limited Optical Cavity with Low Acceleration Sensitivity

We develop and demonstrate a compact (less than $6$ mL) portable Fabry-P\'{e}rot optical reference cavity. A laser locked to the cavity is thermal noise limited at $2\times10^{-14}$ fractional frequency stability. Broadband feedback control with an electro-optic modulator enables near thermal-noise-limited phase noise performance from $1$ Hz to $10$ kHz offset frequencies. The additional low vibration, temperature, and holding force sensitivity of our design makes it well suited for out-of-the-lab applications such as optically derived low noise microwave generation, compact and mobile optical atomic clocks, and environmental sensing through deployed fiber networks.