Design Of Unstable Resonator And Thermal Stability For Rod Type Solid State Heat Capacity Laser(SSHCL)

The Solid-state heat-capacity laser (SSHCL) has been the focus for its peculiar operation mode (heat-capacity operation), high-energy output and excellent beam quality. Quite different from the process in single-shot and steady state operation, in the heat capacity mode, no cooling is present as lasing proceeds and the waste heat is stored in the active medium itself.Except for operation, heat-capacity laser is similar to conventional laser, but its peculiar operation mode results in big differences in the thermal effect of mediums. Under the study on SSHCL resonator and thermal lensing in this paper, designing rules are given for unstable resonator with a thermal lens. With the analysis of optimum magnification, a virtual confocal unstable resonator is built on a Nd:Glass rod type laser and runs well. The general expressions are derived for the thermal focus length, with the study on temperature gradients in laser rods. The thermal lesnsing properties in heat-capacity and steady-state operation are compared by numerical solution. Experiments for measuring thermal focus length, give accordance with the calculation basically. Also a method to dynamically compensating the thermal lensing is discussed.