Date of Award
Master of Science
Department of Engineering Physics
David E. Weeks, PhD
An understanding of spontaneous emission processes within microcavities is crucial in addressing the need to make tomorrow's microlasers more efficient. One approach to improving the device efficiency is to reduce the threshold input energy at which lasing begins to occur. It has been suggested that the threshold in a microcavity laser can be decreased by increasing the fraction of spontaneous emission into the lasing mode, this can be accomplished by preferentially coupling the gain medium of the laser to the electromagnetic cavity mode of interest. It therefore becomes necessary to understand the mechanism by which this coupling takes place. This research develops a fully quantum mechanical description of the interaction between a gain medium modeled as a two level atom and a multimode electromagnetic field in a microcavity. Atomic transition probabilities are computed for systems in which the atom couples through a single photon process to electromagnetic cavity modes which range in number from two to 2000. Calculations performed for cavities with widely spaced modes demonstrate that atoms exhibit Jaynes Cummings behavior when closely tuned to one mode. Detuning of the atom from the mode inhibits the exchange of energy, while increasing the strength of the coupling to the mode amplifies this exchange. Two level systems strongly coupled to many closely spaced modes exhibit spontaneous emission rates characteristic of an atom in free space.
DTIC Accession Number
Ziegler, Dustin Philip, "Spontaneous Emission in Microcavity Lasers" (1997). Theses and Dissertations. 5797.