| Electromagnetically induced transparency (EIT) is the term used to describe how the absorption of a weak (probe) laser beam by a three-level atomic medium can be significantly reduced by the presence of a second strong (coupling) laser beam. The behavior of EIT is very sensitive to several experimentally variable parameters, including frequency detunings and laser intensities. Kerr nonlinearity is also enhanced near conditions of EIT. These behaviors have made EIT systems very interesting for studying optical switching and other manipulation of optical signals, and this dissertation describes research into such possibilities. In particular, the control over optical bistability from an EIT medium in an optical cavity is studied and used to implement a new technique for optical switching. Next, the transfer of a frequency modulation of the coupling beam to an amplitude modulation of the probe beam in an EIT system is numerically modeled and experimentally measured, and the physical parameters that are most limiting to this type of signal transfer are identified. Furthermore, a spatial modulation of the coupling beam intensity in an EIT medium creates an electromagnetically induced grating, which is shown to reflect part of the probe beam. This behavior is harnessed to demonstrate a new technique for all-optical switching and signal routing, and the dependencies on laser detunings and intensities for this behavior are experimentally examined. |
