Self-passive Q-switching of a Nd:YAG laser

Abstract

Q-switching techniques that modify the quality factor of a laser resonator are normally used to generate short pulses in a solid-state laser. The saturable absorber based technique, also known as passive Q-switching, is operationally attractive and simple when compared with mechanical or active optical techniques. Cr4+:YAG is a common saturable absorber material for many laser materials including Nd:YAG for operation around 1 μm wavelength. Recently, self-passive Qswitching using a Nd:YAG gain medium that is externally implanted with chromium ions through annealing process has been demonstrated. Pulsewidths up to 2μsecs and PRFs up to 100kHz have been demonstrated. In this paper, the improved annealing technique utilized to obtain chromium doped Nd:YAG crystals is discussed. Tailored dopant chromium ion profile inside a host laser material is shown to provide controlled temporal lasing characteristics. The current technique is applicable to several other laser gain media. The present technique simplifies laser cavity configuration, eliminates alignment issues that could exist between the gain medium and passive Q-switch crystal, and aids in the rugged packaging of a laser module.