The problem of optical field chaos in a storage ring free-electron laser oscillator has been discussed by using a phenomenal model. From the theoritical analysis and numerical simulation, it can be found that the chaotic transition of the system via perioddoubling bifurcation still exists when there is a pulsed gain modulation, instead of an oscillated one, in the optical cavity. The existence of optical field chaos has been confirmed by calculating the corresponding value of the leading Lyapunov characteristic exponent. A further research shows that the real form of gain modulation in the optical cavity is most likely a pulsed one, not an oscillated one.

The problem of optical field chaos in a storage ring free-electron laser oscillator hasbeen discussed, by using a phenomenal model. From the theoritical analysis and numerical simulation, it can be found that the variation of laser intensity versus time can be both periodical and chaotic when there is a weak gain modulation in the optical cavity. The correspondent leading Lyapunov characteristic exponent goes to a negative and a positive real number as time increases. Afurther research is carried out, and a chaotic transition via period-doubling bifurcation has been found by varing the modulation parameters.