Frequency stabilized laser source at around 2.09 mu m by locking to (HBr)-Br-79 and CO2 transitions

A tunable Tm-Ho:YAG laser was fabricated, characterized and used to perform high-resolution spectroscopy of several molecular absorption lines of HBr and CO2 at around 2090 nm. Frequency locking of this laser source to the (HBr)-Br-79 P(12) transition at 2097.222 nm and to the CO2 P(22) transition at 2087.844 nm was then achieved using the fringe side locking technique. The frequency stability obtained was first evaluated by monitoring the error signal of the control loop, giving a root mean square (rms) value of similar to30 kHz for the residual frequeney fluctuations with both molecular frequency references. A further stability analysis was performed by monitoring the beat note between two independently stabilized Tm-Ho:YAG lasers, giving a two-sample deviation of the beat frequency below 100 kHz for all integration times between 1 mus and 0.1 s.