High Energy Eyesafe Transmitter for LADAR

The most widely used solid-state laser technology is based on Nd-doped laser materials, providing output in the 1050-1060-nm wavelength region. Alternative materials can provide other wavelengths more suited for eyesafe ladar, but systems using thesematerials have shown substantial limitations in either or both power output and efficiency. For focal-plane-array (FPA)-based ladar (also referred to as flash ladar) systems in particular, the need to generate a combination of high energies and shortpulses eliminates many solid-state lasers from consideration. In the work proposed here, we take advantage of recent developments in solid-state laser design, new laser materials (Tm:YLF and Ho-doped YLF or YAG), and improved high-power semiconductorlasers to develop an efficient, compact, high-power laser system in the 2050-2100-nm wavelength region. Our innovation is the combination of: 1) our side-pumped, conduction-cooled, multi-pass slab design proven to operate with a variety of laser crystals,2) the laser crystals Tm:YLF, Ho:YLF and Ho:YAG, and 3) high-power, efficient diode lasers based on aluminum-free active layers. We anticipate the demonstration of a Tm:YLF-pumped, Q-switched Ho-doped eyesafe laser with >100-mJ output energy,approximately 10-ns output pulsewidth, and a maximum operating pulse rate of 60 Hz at the completion of this program.