Novel Nanocomposite Refractive Index Tuning Mechanism Based on Controlling Embedded Particle Morphology

This study investigates the embedded nanoparticles’ morphology and distribution effects on the effective refractive index (RI) of composite. The study is based on the FEA model for the Fabry-Pérot interference cavity made from the nanocomposite film. The composites’ effective RI can be derived from the simulation reflection spectrum. In constant particle volume fraction condition, the embedded particles with a larger diameter, locating at the region with high electric field and having longer side length along the electric field oscillating direction, are identified as the factors to reinforce the effective RI. For 4 μm incident light-wave, as controlling the diameter from 24.8 nm to 212 nm, distribution from middle-gathered (high electric field region) to top-bottom gathered (low electric field region), and the rectangular cylinder particle shortest side along electric field oscillating direction to longest side along electric field oscillating direction, the effective RI increasing from 1.687 to 1.719, 1.638 to 1.745 and 1.66 to 1.901, respectively. The underlying RI shifting principle is recognized from the light scattering loss by embedded nanoparticles. This discovering provides one novel idea for next-generation real-time RI tuning structure and device.