2025/09/25 by Mičulka, Martin, Liu, Jinsong, Beer, Sebastian +9
#Applied Physics (physics.app-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Optics (physics.optics)
paper · doi:10.48550/arxiv.2509.21583
The systematic exploration of ABC type heterostructures reveals that nanoscale morphological modification markedly improves nonlinear optical properties to maximize the artificial bulk second-order susceptibility. These amorphous birefringent heterostructures are fabricated through cyclic plasma-enhanced atomic layer deposition of three oxides, effectively breaking centrosymmetry. We observe a dependence of optical nonlinearity on the thickness variation of three constituent materials: SiO2 (A), TiO2 (B), and Al2O3 (C), ranging from tens of nanometers to the atomic scale, and these materials exhibit second-order susceptibility at their interfaces. Our findings reveal that the enhancement of nonlinear optical properties is strongly correlated with a high density of layers and superior interface quality, where the interface second-order nonlinearity transitions to bulk-like second-harmonic generation. An effective bulk second-order susceptibility of χzzz\nobreakspace=\nobreakspace2.0\nobreakspace±\nobreakspace0.2 pm/V is achieved, comparable to typical values for conventional monocrystalline nonlinear materials.