Frequency stability and stabilization of a chemical laser

We have built a low-power CW HF/DF chemical laser, designed to achieve high-frequency stability. Measurements are reported which characterize the instantaneous spectral width of the laser output to less than one part in 10
¹¹
(
\Delta\nu < 1
kHz) and the variations in absolute frequency of this emission with time to four parts in 10
¹⁰
(
\Delta\nu = \pm20
kHz) per 0.1 ms. Two experiments to actively stabilize the laser frequency are reported. In one experiment the laser was locked to a high-finesse Fabry-Perot to five parts in 10
⁹
(
\Delta\nu = \pm250
kHz) for many minutes. In the other experiment one laser was locked to another using heterodyne beat spectroscopy to 1.7 parts in 10
⁹
(
\Delta\nu = \pm85
kHz). The stabilization experiments were limited by the feedback loops used.