Absolute laser frequency stabilization to R(3) absorption line of HI at 1541.06 nm

An Extended-Cavity Laser Diode was used to perform high resolution spectroscopy of molecular absorption lines of hydrogen iodide. For the first time, this laser source was frequency locked to an HI transition at 1.5 mu m using the wavelength modulation technique. Preliminary measurements of the closed-loop error signal provided a relative frequency stability of 2 x 10(-9) in a 10 Hz acquisition bandwidth.