Photonic band in two-dimensional lattices of micrometer-sized spheres mechanically arranged under a scanning electron microscope

TLDR

The study demonstrates that mechanically arranging micrometer‑sized dielectric spheres enables systematic investigation of photonic band effects. The authors fabricated 2.1‑μm dielectric‑sphere photonic crystals by micromanipulation in an SEM and measured transmission spectra of a finite 91‑sphere lattice to extract photonic band dispersion curves. Transmission measurements revealed a progressive buildup of photonic bands from whispering‑gallery modes as lattice size grew, and the experimentally obtained dispersion matched numerical predictions for an infinite lattice.

Abstract

Two-dimensional photonic crystals of dielectric spheres with a 2.1 μm diameter have been fabricated by arranging individual spheres using a micromanipulation technique in a scanning electron microscope. A buildup of photonic bands from whispering gallery modes has been observed as the number of spheres increased, by measuring the transmission spectra for lattices composed of various numbers of spheres. The photonic band dispersion curves were experimentally obtained for a finite system made of 91 spheres from the transmission spectra for oblique incidence in the near-infrared region. They were in good agreement with the results of a numerical calculation for an infinite lattice. Since this mechanical manipulation technique enables us to control the arrangement of individual optical wavelength-sized scatterers, it provides a new way to systematically investigate various photonic band effects.