Ultra‐Broadband Spectral Chaos in Random Fiber Laser for Optical Encryption

Chaos‐based encryption techniques have been widely employed to secure optical information in both temporal and spatial domains. Yet, chaotic spectral encryption has received limited attention due to the significant challenge in broadband spectral chaos generation. Here, we report broadband spectral chaos generation in a random fiber laser, achieving a record‐high spectral complexity with up to 21 157 spectral spikes spanning 900–1700 nm. Multiple nonlinear processes, including stimulated Brillouin scattering, stimulated Raman scattering, and four‐wave mixing, are activated at an optimized pump power, giving rise to rich and unpredictable spectral dynamics. The randomness of the chaotic spectra is validated through a comprehensive statistical analysis of 1001 recorded spectral realizations. Leveraging the broadband spectral chaos, we realize simultaneous spectral encryption of multi‐bit binary digital signals. This work unveils a new chaotic dimension in laser physics with significant implications for data encryption and high‐entropy random sequence generation. Moreover, its inherent extreme sensitivity to perturbations suggests potential applications in ultra‐precise sensing technologies.