Exploiting structural nonlinearity of a reconfigurable multiple-scattering system

Nonlinear optics is a rapidly growing field that has found a wide range of applications. A major limitation, however, is the demand of high power, especially for high-order nonlinearities. Here, by reconfiguring a multiple-scattering system, we introduce 'structural nonlinearity' via a nonlinear mapping between the scattering potential and the output light. Experimentally we demonstrate high-order, tunable nonlinearities at low power. The multiply-scattered light features enhanced intensity fluctuations and long-range spatial correlations. The flexibility, robustness and energy efficiency of our approach provides a versatile platform for exploring structural nonlinearities for various applications.