Gain-Switched Ti:Sapphire Microchip Laser: Spectroscopic and Laser Characteristics Within 5-300 K Temperature Range

Ti:Sapphire (Ti ³⁺ :Al 2 O 3 ) is a broadly-tunable vibronic solid-state laser material allowing laser emission in the visible and near-IR wavelength region. Its broad gain bandwidth (650–1100 nm) makes Ti:Sapphire the most popular choice for widely tunable laser sources, as well as for ultrashort pulse generation. However, the major disadvantage of this laser is the relatively short upper laser level lifetime of $3.2\ \mu\mathrm{s}$ (at room temperature) resulting in a relatively high saturation power and oscillation threshold. The short upper laser level lifetime is also not favourable for generation of Q-switched pulses with ns-pulse duration, required e.g. in dermatological or cosmetic lasers. Nevertheless, by gain-switching method, the nanosecond or even sub-nanosecond pulses can be efficiently extracted from the Ti:Sapphire laser [1]. Pulse duration of the Q-switched and gain-switched pulse is proportional to a cavity lifetime, i.e. the shorter the lifetime is, the shorter pulses can be generated. From this point of view, microchip lasers, having typical cavity lengths of the order of millimeters, allow generation of gain-switched pulses that are much shorter than can be obtained with more conventional solid-state lasers [2].