Frequency stabilization of a semiconductor laser using water-vapor absorption lines

Distance measurements based on the principle of optical interferometry requ ire stabilized laser frequencies. Recently frequency stabilization of laser s has been successfully achieved using, for example, rubidium and iodine ab sorption fines. These materials are used to stabilize a single frequency. F or some applications, especially in the field of optical metrology, it is n ecessary to stabilize several wavelengths in a region of about 10 nm simult aneously. The simple molecule water vapor shows a system of many vibrationa l-rotational absorption lines in the near-infrared region. We show that it is possible to use water-vapor absorption lines for frequency stabilization by locking a semiconductor laser to the 791-nm (379-THz) absorption line. We discuss the stability of a synthetic wavelength that could be achieved b y stabilizing two lasers independently on two different water-vapor absorpt ion lines. (C) 2001 Society of Photo-Optical Instrumentation Engineers.