400 Hz Line Center Stability in a GaAlAs Diode Laser

Frequency-stabilized semiconductor lasers are practical sources for a wide variety of potential applications including remote sensing, laser spectroscopy, optical frequency standards, coherent optical communication, coherent optical sensors, laser gyroscopes, etc. In particular diode lasers are convenient sources for injection locking tunable solid state lasers. Solitary semiconductor lasers are essentially impervious to acoustical and mechanical disturbances since they have no external optics. On the other hand, the operating frequency of a semiconductor laser is very sensitive to temperature and current variations, therefore standard diode laser systems have very poor frequency stability. Thus the first step in frequency stabilizing a diode laser consists of stabilizing the temperature and injection current of the laser.