Laser physics and laser techniques

Research involving femtosecond-process measurement in the frequency domain, laser surface transformations and damage mechanisms, the study of specific quantum-well structures, and the development of optical beam expanders were completed. In particular, attempts to suppress troublesome thermal-grating effects in frequency-domain measurements of femtosecond processes produced two entirely different and successful techniques, each of which yields other advantages as well. Our studies of laser-solid interactions have led to a better understanding of transient electronic processes in very dense and hot electron-hole plasma in semiconductors and of the formation of single-lase-beam-induced spontaneous surface ripples on a multitude of solid materials. Our time-resolved studies of GaAs/AlxGa1-xAs quantum well structures successfully measured the photoluminescence decay times of carriers in structures grown by both molecular beam epitaxy and metalorganic chemical vapor deposition. Much was learned about the nature of nonradiative recombination dynamics in these structures. Results consistency indicated that the fundamental radiative recombination coefficient, B, in quantum wells is quite small. Optimal designs were developed for achromatic prism beam expanders, based on a remarkedly simple and elegant theoretical analysis.