Generation of high-complexity laser chaos with asymmetric filtered feedback enabled by Fano metasurfaces

Based on Fano metasurfaces, we propose a universal laser chaos model with asymmetric filtered feedback (AFF). Different from conventional optical feedback (COF), laser chaos has intrinsic degrees of freedom from Fano resonance, including the lineshape symmetry, resonant frequency, and linewidth. Compared with the Lorentzian optical feedback (LOF), AFF improves the complexity and eliminates the time-delay signature by the nonlinear interaction. In the steady-state phase space, we identify that the asymmetric factor q controls the distribution of external modes and antimodes. With the intrinsic instability of a number of eigenmodes, both the optical spectrum and the power spectrum have broadened by several GHz. Moreover, we demonstrate random number generation with a rate of 20 Gbit/s based on the chaos source. Our results show that the multidimensional light field manipulation capabilities of metasurfaces open up new possibilities for laser chaos, enabling the realization of exotic nonlinear dynamical phenomena.