Cavity-enhanced second-harmonic generation in strongly scattering nonlinear media

Abstract

Light interaction with random linear or nonlinear media is always an interesting scheme to study Anderson localization of photons and phase-matching-free nonlinear optics. Here, a cavity-enhanced second-harmonic generation (SHG) process in a random nonlinear material was experimentally demonstrated. Compared to the conventional random laser action based on the photoluminescence (PL) effect, this cavity-enhanced SHG indicates a possible Anderson localization of the nonlinear signals by ring cavities and widens the response wave band due to the flexible frequency conversion in the nonlinear process. The combination of the random cavity scheme and the random quasi-phase-matching scheme will provide us another way to break phase-matching limitations, with locally high conversion efficiency. This work suggests important progress on nonlinear Anderson localization and indicates many potential applications, such as a band-tunable random nonlinear laser, phase-matching-free nonlinear optics, and even focusing or imaging through random nonlinear media with a nice conversion efficiency.