VCSEL-based CPT atomic clock: Understanding the magic modulation index

Since the earliest VCSEL-based CPT experiments [1] it has been known that there are modulation regimes that allow the measured clock frequency to be largely independent of laser intensity. We describe a quantum optics model of the VCSEL-based CPT clock and compare the model to recent experimental lineshape data. This is part of a stringent test of the computation of coupled channel AC stark effects in multiphoton processes. \newline \newline [1] Vanier, J., A. Godone, F. Levi, S. Michalizio, ``Atomic Clocks Based on Coherent Population Trapping: Basic Theoretical Models and Frequency Stability,'' Proceedings of the 2003 IEEE International Frequency Control Symposium, Pg. 2-14.