Abstract

A solid state laser operated high above threshold cannot easily maintain single-longitudinal-mode output. However, high power single-longitudinal-mode output can be achieved by injecting a singlelongitudinal-mode pulse from a near-threshold laser into the high power laser. We have devised a resonator configuration wherein the functions of the near-threshold injecting laser and the highpower injected laser are integrated into a single laser. The self-injection-locked laser consists of a single laser head and two resonators which are selected by an electrooptical element and a thin-film polarizer. Lasing starts in the lossy resonator arm which contains the line-narrowing and tuning elements and is operated close to threshold. The lasing in this arm is detected by a photodiode which triggers the switching of the electrooptical element, thus redirecting this small line-narrowed signal into the bare-cavity arm to injection-seed the Q-switched output pulse. We have obtained >100 mJ in 40-ns pulses which are single-longitudinal and transverse modes. Higher intracavity power densities are observed without optical damage in this single-transverse-mode resonator than are usually obtained in conventional multitransverse-mode oscillators. We attribute this behavior to the more uniform spatial profile.

© 1985 Optical Society of America