Effects of an Intracavity Resonant Medium on an Optical Cavity

Optical cavities provide sensitive detection of rotation through the shift in the cavity resonance frequencies, resulting from the Sagnac effect. We investigated the use of the anomalous dispersion, asscioated with an absorption resonance from an intracavity medium, for increasing the frequency separation of the cavity modes. Using a simple Fabry-Perot resonator with an intracavity rubidium vapor cell, we experimentally demonstrated the increase in the cavity scale factor, and found it to be in good agreement with theory for our absorption resonance, with small deviations resulting from the multi-level nature of the Rb87 D2 transition.  The widths of the cavity resonances, modified by the presence of the dispersive medium, did not grow as quickly as the scale factor, resulting in increased cavity sensitivity, a finding contrary to previous expectations. We also demonstrated that the ground state hyperfine structure of the Rb87 atom can be used to tune the cavity scale factor via the technique of optical hyperfine pumping.

Krishna Myneni

U.S. Army RDECOM