Experimental study of the improved optical system for the LED-pumped solid-state lasers

In this article, an optical system for pumping the active medium of solid-state lasers with light-emitting diodes (LEDs) is introduced to upgrade the master oscillator of the laser fusion facility. The optical system is based on the guiding of optical rays from light-emitting diode sources to laser rods by means of total reflecting surfaces. Three different configurations with four, five, and six segments have been designed and their geometry is optimized with 3D random ray-tracing method to obtain the best performance. The pump systems have been fabricated and successfully applied to pump a 3 mm diameter laser rod with 10 watts white spectrum LEDs. Using five segments configuration and 4 Joules electrical energy delivered to 35 LEDs, the laser oscillator produced laser spikes with multi-mode Ince-Gaussian transverse beam structure and more than 700 micro-joules laser energy at a 1 Hz repetition rate. Moreover, the Q-switched pulses with an average energy of about 35 micro-joules and 230 ns pulse-width have been generated with the optimized optical pump system. More improvement to the LED-pump system is possible, which can be led to an efficient multi-mJ laser beam.