Modified Pound-Drever-Hall scheme for high-precision free spectral range measurement of Fabry-Perot etalon

摘要

Improvement of two orders of magnitude of the Pound-Drever-Hall based free spectral range (FSR) measurement method is reported. The improved technique results in 1 part in 10~6 precision. This is believed to be the most precise measurement of FSR.rnIntroduction: Fabry-Perot etalons are used widely in communication and laser frequency stabilisation. High-finesse etalons are also used to stabilise the optical frequencies of low-noise modelocked lasers where a precise measurement of the etalon free spectral range (FSR) is critical to match the laser mode spacing to the FSR.