Polarization-dependent refractive index analysis for nanoporous microcavities by ray tracing of a propagating electromagnetic field

• Published in: Optical materials express Vol. 11; no. 9; p. 2924
• Main Authors: Mikami, Yuya, Yoshioka, Hiroaki, Obata, Nasim, Han, Sangmin, Oki, Yuji
• Format: Journal Article
• Language: English
• Published: Washington Optical Society of America 01.09.2021
• Subjects: Effective medium theory; Electromagnetic fields; Electromagnetism; Geometrical optics; Mathematical models; Microcavities; Nanoparticles; Optical properties; Optics; Polarization; Ray tracing; Refractivity; Silicon dioxide; Simulation
• ISSN: 2159-3930; 2159-3930
• DOI: 10.1364/OME.434394

In this study, we demonstrated an accurate estimation of the refractive index in nanoporous structures using a novel hybrid simulation method that combines electromagnetic field analysis and ray tracing based on wave optics and ray optics. A novel theoretical model for the refractive index in a nanoporous structure was developed using a simulation of the effective medium approximation (EMA) and screening effect with consideration of polarization dependence. The optical properties were then experimentally evaluated on aggregates of silica nanoparticles. Based on the measured properties, nanoparticles were predicted to have sufficient transparency for the optical cavity. A nanoporous microdisk laser was thus fabricated with laser dye to demonstrate that the nanoporous microdisk was capable of lasing. The microdisk functioned sufficiently as an optical cavity and had well-matched characteristics. This study provides a novel viewpoint of polarization dependence to estimate the refractive index of nanoporous materials by combining numerical simulations and experiments.