Abstract

Recently, Shy and Yen¹,² stabilized a CO₂ laser at the Lamb dip using the optogalvanic signal in a dc glow discharge of low pressure N₂-CO₂ gas mixture. This method can be applied to regular, sequence- and hot-band laser transitions. However, it has several difficulties, e.g., it is not easy to have stable discharge at a pressure <500 mTorr and the signal-to-noise ratio (SNR) is strongly dependent on the conditions of cathode. In this paper, we present our results on the optogalvanic Lamb dip frequency stabilization of a CO₂ laser using rf discharge. The experiments were carried out in a weak rf glow discharge driven by a Colpitts oscillator.³ The gas mixture (1:1 CO₂-N₂) slowly flowed through the cell at a pressure from 100 to 300 mTorr. The cell was outside the CO₂ laser cavity. The Lamb dip signal was used to lock a waveguide CO₂ laser with a frequency stability better than 1 × 10⁹.

© 1989 Optical Society of America