The Titanium-Sapphire laser was first demonstrated by Moulton in 1986.  It is created by doping Al₂O₃ with Titanium.  Typical dopings range from 0.03 to 0.15 weight per percent of titanium.  The crystal is slightly more durable than ruby lasers due to the Titanium.  Ti:Sapphire lasers have a broad tuning range, with wavelengths ranging from 650nm (red) to 1100nm (near Infrared), this range includes wavelengths that make remote sensing possible.  This large tuning range is achieved when pumped by an Argon Ion Laser and can be extended to other parts of the spectrum when combined with non-linear optics, being limited by the reflectivity curve of the resonator mirrors.  For optimum output power over the whole spectral range, three different sets of mirrors are used.  High average powers of 28 W·m^-1·K^-1 are possible because of the Ti:Sapphire's good thermo-mechanical properties that are maintained when the crystal is clamped in a water-cooled block.

The laser is pumped by the blue-green band of lines from the Argon Ion Laser, and can withstand 20W of pump power when the crystal is clamped in the water-cooled block.

The Titanium Sapphire is usually excited by other lasers because of a relatively low gain. The low gain of 2.5-3´ 10^-19cm^-1, is a result of such a broad bandwidth. The laser has a relatively short upper-state lifetime of 3.2m s, and the peak absorption occurs near 500nm, see Fig 3.

For spectral ranges with l > 700 nm the titanium-sapphire laser is superior to the dye laser because it has higher output power, better frequency stability and a smaller linewidth. The experimental setup of a titanium-sapphire laser is depicted in Fig 4.

Fig 3. Peak Absorption and Emission spectra of a Ti:Sapphire Laser

Source: Lecture notes by Alex Mazzolini, PFOm7a3

Fig 4. Experimental Setup of a Ti:Sapphire Laser