Two-micron thulium-pumped-holmium laser source for DIRCM applications

摘要

There is an increasing need for the generation of mid-infrared radiation in the 3 to 5-micron region especially in the absorption minima of the atmospheric windows. Recent progress in heat seeking detector technology, operating in these atmospheric windows, make it necessary to develop compact and reliable mid-infrared laser systems that can be installed in airborne platforms. Future DIRCM systems will be equipped with high repetition rate/low energy per pulse lasers as well as low repetition rate/high energy per pulse lasers. We report on the development of a Tm:YLF-fiber laser (1.908 &mgr;m) pumped Ho:YAG (2.09 &mgr;m) high energy laser system with pulse energies up to 90 mJ at pulse lengths close to 20 ns and operating at 100 Hz. Using single mode fiber lasers as end-pumped sources for the master-oscillatorpower- amplifier (MOPA) system almost diffraction limited beam quality resulted. The frequency conversion into the 3 to 5-micron region is performed with a zinc germanium phosphide (ZGP) crystal in a linear or ring resonator. Propagation of the mid-infrared laser beam through moderate turbulent atmosphere will be simulated numerically using phase screens and Fresnel transformation.