Titanium doped Sapphire
Titanium doped Sapphire (Ti:Sapphire or Ti3+:Al2O3) is the most widely used crystal for wavelengths tunable lasers and femtosecond lasers. The crystals are grown using Czochralsky and Ciropolous techniques. Ti:Sapphire combines the excellent thermal, physical and optical properties of Sapphire with the broadest tunable range of any known material. It can lase over the entire band from 660nm to 1100nm. Frequency doubling provides tuneability over the blue-green region of the visible spectrum.
Ti:Sapphire crystals are active media for highly efficient tunable solid-state lasers. They demonstrate good operation in the pulsed-periodic, quasi-CW and CW modes of operation. Ti:Sapphire is a 4-level-system, Vibronic laser with fluorescence lifetime of 3.6µs. The peak of the absorption band is 490nm which makes it an excellent material for being pumped with a variety of sources operating in the green-argon ion, copper vapor, frequency-doubled Nd:YAG, and dye lasers are routinely used. Crystals have also been flashlight pumped by lamps designed to allow short fluorescence lifetime. These factors and broad tuneability make it an excellent replacement for several common dye lasing materials.