چكيده به لاتين
Abstract:
This PhD. Dissertation consider the new generation of solid state lasers, in which thin disk crystal uses as active medium. This type of lasers has been considered in recent years, due to their excellent properties. Pumping mechanism in thin disk lasers plays an important role in efficiency and output laser beam quality. So the optical pumping and its modification methods investigated here by simulation and experimentally, in order to improve manufactured thin disk lasers in “Iranian National Center for Laser Science and Technology” (INLC). According to previous studies, as much as the pumping area is closer to circular shape and pumping absorption density is more uniform in this area, the laser shows better efficiency and output beam quality. At first in this thesis, the reasons of non-uniformity in pumping absorption density and deviation of pumping spot from desired shape are investigated. Then based on simulation investigations by “Trace-ProTM” software, a few methods are suggested to overcome the problems. The methods are examined experimentally by appropriate laboratory setups. In low pumping power, the empirical results confirm simulation predictions of pumping spot quality improvement, and higher laser efficiency as well. In continue, to prepare high power beam source for thin disk laser pumping, a simple way in combination of four laser-diodes radiations introduced. Computer simulations confirm the ability of suggested pumping modifications, to provide acceptable pumping spot, in this high power pumping setup. Simulation results are tested through experimental measurements in laboratory setups. Experimental results show that, by adapting the pumping parameters, the modified setups can improve laser characteristics in our introduced high power pumping in agreement with simulation results. At last, due to the fact that the number of passes of pumping beam through the active medium in thin disk laser pumping has a key role in laser parameters enhancements, a simple method for increasing the number of pumping beam passes through the disk is introduced. This method examined by setup simulation and experimental measurements. Required facilities and desired conditions under those, the usage of introduced multipass configuration becomes efficient, is discussed.
Keywords: thin disk laser, thin disk laser pumping simulation, pumping spot improvement in thin disk laser, multipass system, laser-diodes radiation combination.
