Nonlinear optics with local phasematching by quantum-based meta-material

We propose a novel artificial medium, which locally provides both the optical nonlinearity and simultaneously the phasematching for the macroscopic build-up of the generated field. This is achieved by a special assembly of semiconductor quantum wells, which by careful design are both nonlinear and appropriately dispersive. A critical point for a practical realization of this meta-material is its wavelength tuning capability accomplished by applying bias voltage to the semiconductor structure, employing a voltage-controlled tunnelling-induced transparency mechanism. We theoretically demonstrate the quantum-based phasematched nonlinear meta-material principles using a specific structure comprised of GaN/AlN quantum wells providing the required near-infrared intersubband transitions. For this meta-material we estimate the enhanced second-order nonlinearity to be around 10−8 m V−1, while the phasematching, tuned by a single-volt bias improves the nonlinear coherence length from 40 μm up to practically infinity.