Low Temporal Coherence Femtosecond Pulse with Polarization Chaos for Nonlinearities Suppression

Laser pulses with chaotic polarizations exhibit low temporal coherence, while maintaining a single pulse structure and high peak power. Herein, we propose formation of polarization chaos within a single femtosecond pulse via nonlinear phase modulations, and nonlinearities suppression is experimentally verified. A theoretical model based on the Hénon map is established, and validated experimentally through a cyclic feedback fiber loop. The routine from deterministic to chaotic state is characterized by a single-shot, wavelength-resolved polarization measurement system. We identify polarization chaos by analyzing Lyapunov exponent and power spectrum of wavelength-resolved Stokes parameters. By disrupting the phase-matching conditions via chaotic polarizations, we observe that polarization chaos suppresses the efficiency of four-wave mixing with an extinction ratio of 15 dB, and the suppressions of pulse fission and Raman scattering during long-distance fiber propagation are also verified. By forming Hénon-type chaos in polarization space at femtosecond scale, our work provides a universal solution to realize polarization chaos for ultrafast lasers. Such a low temporal coherence femtosecond laser with nonlinearities suppression leverages applications of high power laser propagation, ultralong-distance fiber communication, optical sensing, etc.