Very high Q frequency-locked Fabry–Perot cavity

We report measurements on a 1.75 m long Fabry-Perot cavity locked to a Nd:YAG tunable laser using the Pound-Drever technique. The cavity decay time was measured to be about 291 μs corresponding to a quality factor Q of about 5X1011, the highest value ever reported for an optical resonant cavity. © 1996 American Institute of Physics.