Temporally variable, tunable solid-state laser source for scientific and medical applications

Abstract

Solid-state vibronic lasers can now be made whose pulses tune in time as well as in frequency. "Pulse stretching," or control of temporal pulse duration and shape, is effected by newly developed techniques involving intra-resonator electro-optic feedback. The physics of electro-optic feedback controlled lasers is discussed, and an alexandrite laser employing a very fast electro-optic feedback system is described. Experimental characterization of this system has demonstrated broadly tunable (720-800 nm), variable duration (100 ns–5 μs) pulses with pulse energies of several hundred millijoules. Although a number of factors affect pulse temporal and amplitude stability as well as pulse shape, temporal fluctuations of only a few percent have been achieved. These pulses are sufficiently stable and reproducible to be reliably upconverted into the UV by second harmonic generation (SHG). The characteristics of microsecond duration "stretched" pulses are reported and a number of interesting new applications in science and medicine are described. These include applications in sodium lidar, lithotripsy, and dentistry.