The ubiquity of single-crystal Nd:YAG lasers belies the comparative difficulty in forming and doping the neodymium crystals. Their polycrystalline cousins offer a simpler and more cost-effective fabrication process but, until recently, have not demonstrated quality or effectiveness comparable to single-crystal lasers.

That began to change in December when Japanese and Russian collaborators based at the Institute for Laser Science at the University of Electro-Communications in Tokyo produced a ceramic polycrystalline Nd:YAG laser with an optical-to-optical conversion efficiency of 52.7 percent. Compare this with a single-crystal laser used in the experiment that demonstrated 53.7 percent efficiency. Pumped with 883 mW from a laser diode, the polycrystalline laser achieved 465 mW of continuous-wave output centered at 1064.2 nm with a threshold of 30 mW.