Titanium: sapphire
The amplifier medium titanium: sapphire ( Ti 3+ : Al 2 O 3 ) consists of a weakly birefringent host crystal corundum (Al 2 O 3 ), in which by doping a few hundredths to tenths of a percent by weight of Al 3+ - ions by Ti 3+ ions are replaced. This creates a bright red sapphire , the active medium of titanium: sapphire laser . It absorbs strongly in the range from 400 to 600 nm wavelength (maximum at 490 nm) and fluoresces from 670 to 1070 nm (maximum at 800 nm). In addition, titanium: sapphire has a high thermal conductivity , which enables the pump beam to be focused on a small area without destroying the crystal.
| chemical formula | Al 2 O 3 : Ti 3+ |
| Crystal structure | hexagonal |
| Lattice constants | a = 4.748, c = 12.957 |
| density | 3.98 g / cm 3 |
| Laser activity | 4 level, vibronic |
| Lifetime upper level | 3.2 μs ( T = 300K) |
| Absorption band | 400-600 nm |
| Fluorescent band | 670-1070 nm |
| linear index of refraction | n o = 1.760; n e = 1.752 (λ = 800 nm) |
| nonlinear index of refraction | n 2 = 3.2 · 10 −20 m 2 / W |
| Damage threshold | 4-5 J / cm 2 |
| Melting point | 2040 ° C |