Frequency locking to a high-finesse Fabry–Perot cavity of a frequency doubled Nd:YAG laser used as the optical phase modulator

We report on the frequency locking of a frequency doubled Nd:YAG laser to a 45 000 finesse, 87-cm-long, Fabry–Perot cavity using a modified form of the Pound–Drever–Hall technique. Necessary signals, such as light phase modulation and frequency correction feedback, are fed directly to the infrared pump laser. This is sufficient to achieve a stable locking of the 532 nm visible beam to the cavity, also showing that the doubling process does not degrade laser performances.