Ing-Jye Hwang and D. Stroud, Department of Physics, The Ohio State University, Columbus, Ohio 43210

We calculate the c-axis Josephson plasmon frequency \omega_{pl}(B, T) versus temperature T and magnetic induction B in BSCCO, treating the order parameter fluctuations in the lowest Landau level (LLL)~approximation. The calculation agrees qualitatively with recent field-cooled measurements of Matsuda {\it et al}, assuming a $c$-axis dielectric constant $\epsilon_0 ~~20--50. For any given B, \omega_{pl} falls monotonically with increasing T, remains finite in the flux liquid state, and varies continuously across the solid-liquid transition when disorder is included. We also obtain an expression for \omega_{pl} which is valid everywhere in the flux liquid state and is not restricted to the LLL approximation. This expression leads to \omega_{pl} \sim 1/\sqrt{B} in the flux liquid state, in agreement with experiment.