Modeling broad-band and multiple-frequency energy extraction from glass laser amplifiers

Computer modeling, used previously to predict spectral hole burning and gain saturation in neodymium glass lasers, is extended to treat multiple-frequency and broad-band extraction pulses. For materials having large spectral inhomogeneities, maximum improvements in extraction efficiency are achieved for extraction pulse bandwidths approximately 0.5-1.0 of the effective inhomogeneous linewidth. Using fluorescence line narrowing data, the possible improvements for commercial Nd:silicate and phosphate laser glasses at room temperature are estimated to be less than 10 percent. However, for these glasses, spectral and polarization hole burning is weak, and hence monochromatic extraction is already within 20 percent of that for a homogeneous medium.