Study of the temperature distribution in diode-end-pumped solid state-lasers

Abstract

The main problem of bulk crystals for the realization of powerful lasers is their poor management of thermal effects. Optical pumping is associated with the heat generation in solid state laser materials. Moving of heat toward the surrounding medium which is mostly designed for the cooling management causes thermal gradient inside the medium. This is the main reason of appearance of unwanted thermal effects on laser operation. Thermal lensing, thermal stress fracture limit, are some examples of thermal effects. In this work an investigation of heat generation inside the rod crystal during optical pumping was carried out. The Finite Difference Method (FDM) was used to resolve the heat differential equation in order to calculate the temperature generated in Yb:YAG with diode-end-pumped configuration. The effect of the conductance was studied by using two methods of the cooling system. In the first method the crystal is directly in contact with water. In the second method the crystal is surrounding by a copper to keep the cylindrical surface at the define temperature. The temperature generated reduced to half by using the second method and we can conclude that it is the best choice for high power end pumping system.