Praseodymium solid state lasers at 5.2 and 7.2 microns-longest rare earth wavelengths to date

The goal of our research program is to extend the useful range of rare earth solid state lasers into the mid-infrared range; 3<λ<10 μm. Toward this goal, we have explored the optical properties of rare earth ions doped into unconventional host crystals. As a demonstration of this technique, we have developed two new mid-IR lasers using the rare earth praseodymium. These new praseodymium lasers can now provide compact and efficient sources with emission lines centered at 5.2 and 7.2 μm