The performance of a longitudinal Zeeman-stabilised He-Ne laser (633 nm) with thermal modulation and control

The frequency stability performance of a small internal-mirror stabilised laser is presented. The statistical frequency stability is 5*10-10 for one-second averages, and is white-noise limited for averaging times between 100 ms and 10 min. The long-term reproducibility has been investigated over four years. It is the sum of the day-to-day resettability (+or-5*10-10) and the gas clean-up effect, which gives rise to a drift rate of -1*10-11 per hour of operation.