The Study Of The Thermal Effect Of The Active Medium In Solid State Heat Capacity Laser(SSHCL)

The solid state heat capacity laser (SSHCL) concept is firstly produced by C. T. Walters in 1995. He points out that the TIL (Thermal Inertia Laser) approach to laser design is conceptually fairly simply and has potential to offer revolutionary strides in output power. In heat capacity operation the laser operation is broken into two discrete processes. During the lasing step the active medium is thermally insulated and no cooling is present. Cooling takes place during a separate sequence when the laser is not operating. In this operation, before this system works, the temperature of the active medium drops to a certain temperature (initial temperature), the active medium is not cooled while lasing and the waste heat is deposited in active medium. The active medium is cooled rapidly after lasing, and then another new lasing comes on. One of the key features of this heat capacity approach is the inversion of the temperature profile through the medium as compared to conditions where the laser is actively cooled while lasing takes place. In this capacity mode, the active medium is hotter on the surface than in the center, thereby inducing compressive stresses on the large faces. In conventional operation, where the active medium is actively cooled during the lasing burst, the active medium is cooler at the large pump faces than in the center, resulting in tensile stresses on theses faces. Since dielectric materials are inherently several factors stronger in compression than in tension, this temperature reversal increases the inherent fracture limit of the system and allows a heat capacity operated laser to be pumped much harder than a conventionally operated laser.In our country, the SSHCL has not been outspreaded until recently, and we know the thermal effects of the active medium comparatively less. Based on this, this paper starts from the heat diffusion equation, considering the initial and boundary conditions of the active medium, then produces the transient temperature and stress distribution in Xeon flash lamps pumped cylindrical laser rods and slabs for single-shot and repetitively pulsed operations in the heat capacity operation.Then this paper gives out the simulations for the thermal effects of the active mediums. Eventually we work out the interference experiment to measure the temperature rise of the active medium. After we know the temperature change of the active medium exactly, we can compensate the thermal distortions real-timely and improve the beam quality.