Ballmann, Charles Wesley (2017-04). Applications of Nonlinear Optical Gain Mechanisms from Phonon and Atomic Vapor Interactions. Doctoral Dissertation.
Thesis
There are many methods to achieve optical gain for laser applications; such methods have been used to make improved spectroscopy and microscopy apparatus. In particular, gain from acoustic and atomic interactions has attained much interest, as is evident in the literature. In this work, we report the results of several experiments involving nonlinear Brillouin scattering and three-level gain in rubidium vapor. Brillouin scattering, both spontaneous and stimulated, in principle result from the scattering of light off of acoustic waves in a medium. While both spontaneous and stimulated Brillouin scattering have been applied to spectroscopy of various samples, from condensed matter to gases, only spontaneous Brillouin scattering has been used for microscopy purposes. We report our result from several proof-of-principle experiments in which stimulated Brillouin scattering and impulsive stimulated Brillouin scattering were applied to microscopic purposes for the first time. We show the advantages these methods afford over spontaneous Brillouin scattering and make a statistical comparison between them. There are also many ways to achieve gain in atomic vapors. Using a setup similar to the stimulated Brillouin scattering setup we performed gain in a three-level ? system in warm rubidium vapor. To our knowledge, this is the first time this three-level analog of Mollow's two-level system with Doppler broadening has been experimentally investigated. Our results show about 0.12% gain in the probe beam. This work, and extensions of it, should provide additional methods of performing spectroscopy and microscopy in various materials from atoms to bulk matter.
