High-frequency optogalvanic signals and co2-laser stabilization

The normal optogalvanic effect used in the stabilisation of CO2 lasers decreases in amplitude with increase in frequency and disappears at 2-3 kHz. We show that there is also a high frequency optogalvanic effect in CO2-N2-He-Xe laser gas mixtures up to 100 kHz, explain its origin and use it to frequency stabilise a laser with long term (hours) frequency drift of < 50 kHz and frequency re-settability of < 100 kHz