Tm:YAP laser crystal (thulium-doped yttrium aluminate) is a high-efficiency laser gain medium operating in the 2 μm spectral band. Its laser output wavelength is stable around 1.94 μm, with slight variations depending on the crystal orientation. Tm:YAP exhibits strong localized absorption in the infrared region, a fluorescence lifetime ranging from 3.81 ms to 4.93 ms, and can withstand temperatures between 30 °C and 1350 °C. The crystal can be cut along the a-, b-, or c-axis, with a-cut and b-cut configurations being the most widely used in laser applications.
The upper laser level (³H₄) of Tm:YAP consists of 9 Stark levels, while the lower laser level (³H₆) comprises 13 Stark levels. Thanks to its excellent absorption around 794 nm, Tm:YAP enables efficient high-power laser operation and is recognized as an outstanding crystal for high-efficiency laser output.
As a 2 μm laser crystal, Tm:YAP holds broad application potential in fields such as medicine, lidar, and atmospheric sensing. For instance, continuous-wave Tm:YAP laser systems delivered via silica fibers show great promise in stereotactic neurosurgery. Fiber-coupled Tm:YAP laser systems are also widely employed in medical applications such as photothermal therapy.
