We have built a Q-switched alexandrite laser which is injection seeded by a diode laser as an illumination source for a rubidium imaging atomic line filter.1 The injection seeding source was a GaAlAs diode laser (Mitsubishi ML-4102) with low output power (3 mW) and narrow linewidth (<30 MHz) at 780 nm. The output frequency of the diode laser was stabilized to an atomic rubidium absorption line by using a reference rubidium cell and a frequency stabilization circuit whose phase sensitive detection of laser frequency modulation yielded the error signal needed for stabilization.2 The alexandrite laser cavity length was controlled to match the cavity resonance frequency to the diode laser frequency. To do this one of the laser mirrors was mounted on a PZT driver, and the necessary information for feedback control was derived from the interference between the injection seeding beams going along different paths. A schematic diagram of the alexandrite laser and both feedback control loops is shown in Fig. 1.
© 1990 Optical Society of AmericaPDF Article