High-brightness stack arrays for DPSSL laser applications

For DPSSL applications at low duty cycle (typically 150 microsecond(s) /20 Hz), we have developed a new concept of `High Brightness' stacked arrays, which leads to power density of 10 kW/cm 2 , and to 40 kW/cm 2 when directly coupled to a lens-duct. The high intensity is made possible thanks to a new proprietary stacking technology that permits a stacking pitch of only 100 micrometers : the principle is to directly stack the arrays without any heat spreaders other than the arrays themselves. When compared to standard commercial QCW stacked arrays, the benefits of using these high brightness laser diodes pumping sources are the following: (1) an important cost reduction related to a drastic simplification in the assembling process, and (2) an improved pumping efficiency associated with an improved brightness (approximately 1 factor 4), consequence of a reduced pitch between linear bar arrays. High-efficiency, frequency-quadrupled, end-pumped 8 mJ, 12-ns-long UV pulses 0.266 micrometers Nd:YAG laser has been developed using these high brightness pump sources. This air-cooled laser is an attractive alterative to the more conventional millijoules-range UV source. A compact high energy 300 mJ Q-switched diode-pumped laser has been developed. Laser performances and integration level demonstration contribute to a preliminary laser design for future airborne laser applications.