Cristal composite SLAB pompé latéralement par diodes laser

This work presents the development of an original concept of a side pumped diode pumped crystal laser for the generation of a high power near diffraction limited beam for material processing applications such as cutting, marking and drilling. An approach based on the modeling of the individual elements constituting the laser oscillator allows the determination of their optimal dimension and of the thermal effects caused by the optical pumping of the crystal laser in order to minimize their influence on the laser beam. The originality of this work consists in using a system of non-imaging coupling optics to transfer the pump laser diode beam towards the laser crystal and an active medium presenting two different doping regions. The coupler allows a high transfer of the pump beam and ensures a profile of absorption in the crystal responding to precise dimensional criteria. This system decreases the divergence angle of the laser diode beam. In contrast to imaging optical systems traditionally used, the coupler present a great tolerance for misalignment. The compound crystal approach ensures a reduction of the elevation of the temperature due to the optical pumping and thus a reduction of the thermal effects on the laser mode. Furthermore, it allows an excellent overlap between the pump absorption and the laser mode, allowing a high global efficiency. An experimental part will permit to verify the elaborated concept.