We demonstrate absolute frequency stabilization of a widely tunable Tm:Ho:YAG laser by locking the oscillator to the <i>P</i>(12) absorption line of the H<sup>79</sup>Br molecule at 2097.222 nm, using the fringe side-locking technique. We perform time and spectral analysis of open- and closed-loop error signals to evaluate the frequency noise. In closed-loop operation a long-term frequency stability of better than 2 MHz with rms frequency fluctuations of ∼112 kHz is obtained over an observation time of 10<sup>3</sup> s.
© 2000 Optical Society of America
M. Marano, P. Laporta, A. Sapia, and P. De Natale, "Absolute frequency stabilization of a tunable Tm:Ho:YAG laser to the HBr P(12) line at 2097 nm," Opt. Lett. 25, 1702-1704 (2000)