Fabrication and properties of gallium metallic photonic crystals

TL;DR

This paper reports the fabrication of gallium-based metallic photonic crystals with high filling factor using a novel infiltration technique, and investigates their electrical and optical properties, revealing a photonic stop band and altered plasma frequency.

Contribution

Introduces a new high pressure-high temperature method to create gallium metallic photonic crystals with 100% filling factor and characterizes their electrical and optical behaviors.

Findings

Ga-opal crystals are metallic networks with resistivity similar to bulk gallium

Pronounced photonic stop band observed in visible spectrum

Effective plasma frequency of infiltrated gallium is lower than in pure metal

Abstract

Gallium metallic photonic crystals with 100% filling factor have been fabricated via infiltration of liquid gallium into opals of 300-nm silica spheres using a novel high pressure-high temperature technique. The electrical resistance of the Ga-opal crystals was measured at temperatures from 10 to 280 K. The data obtained show that Ga-opal crystals are metallic network with slightly smaller temperature coefficient of resistivity than that for bulk gallium. Optical reflectivity of bulk gallium, plain opal and several Ga-opal crystals were measured at photon energies from 0.3 to 6 eV. A pronounced photonic stop band in the visible spectral range was found in both the plain and Ga infiltrated opals. The reflectivity spectra also show increase in reflectivity below 0.6 eV; which we interpret as a significantly lower effective plasma frequency of the metallic mesh in the infiltrated opal compare to the plasma frequency in the pure metal.