LYAPUNOV EXPONENT ANALYSIS OF IRREGULAR FLUCTUATIONS IN A SELF-PUMPEDBATIO3 PHASE-CONJUGATE MIRROR, ESTABLISHING TRANSITION TO CHAOTIC BEHAVIOR

The behavior of the phase-conjugate output from a self-pumped, BaTiO3 phase-conjugate mirror is known to exhibit temporal instabilities unde r certain conditions. Approaches for investigating these experimentall y observed fluctuations indicate the presence of chaotic behavior. How ever, a dynamic system that possesses one or more positive Lyapunov ex ponents is by definition chaotic. For the first time, to our knowledge , we calculate directly from experimental data the largest nonnegative Lyapunov exponent of these irregular fluctuations and report examples of definite transitions from stable to chaotic behavior.