Low-Index Materials for Enhanced Optical Nonlinearities

Low-index materials are well suited for optical nonlinearities due to their inherent ability to enhance electric fields and satisfy phase-matching conditions. Here, we investigate the nonlinear optical properties of the low-index material, aluminum-doped zinc oxide, and demonstrate generation of time-reversed beams and plasmonic strong-coupling signatures in epsilon-near-zero films. Our results corroborate the outstanding potential of low-index materials and provide foundational support for future studies.