Compositionally tuned 0.94-mu m lasers: A comparative laser material studyand demonstration of 100-mJ Q-switched lasing at 0.946 and 0.9441 mu m

A new and innovative composite laser material Nd: YAG(x)YSAG((1-x)) has bee n developed with several objectives in mind; tunability, efficiency, and mi nimization of the deleterious effects of amplified spontaneous emission (AS E) in Q-switched operation. Wavelength tuning to the requisite wavelength 0 .9441 mum was achieved by using the technique referred to as compositional tuning; that is, using nonstoichiometric laser materials to shift the wavel ength for precise tuning. Laser efficiency was achieved by studying the phy sics of 0.94-mum transitions in nonstoichiometric materials; i.e., by exami ng the effects of the host on the linewidth and cross section of of 0.94 mu m neodymium (Nd) transitions. ASE was minimized by choosing materials with a small ratio of 1.06- to 0.94-mum peak cross sections. A comparative study of six different Nd-doped mixed garnet laser material systems was performe d to meet the objectives above. Within these six material systems, over 20 laser materials were spectroscopically analyzed. The optimal laser material was found to be Nd:YAG(x)YSAG((1-x)), which has been demonstrated to lase at the preselected wavelength of 0.9441 mum, an important wavelength for re mote sensing of water vapor. Operating this laser on the F-4(3/2)--> I-4(9/ 2) transition in Nd:YAG((0.18))YSAG(0.82) at 0.9441 mum, has produced for t he first time over 100 mJ in the Q-switched mode. This represents one of th e few lasers that have been designed to operate at a specific, user-presele cted wavelength.