Metallo-Dielectric Photonic Crystals and Bandgap Blue-Shift

TL;DR

This paper investigates how metal infiltration into photonic crystals causes a blue-shift in their photonic stopband, revealing a tunable mechanism for optical properties relevant to photonic device applications.

Contribution

It demonstrates that metal infiltration in photonic crystals induces a predictable blue-shift in the stopband, advancing understanding of tunable photonic structures with metal-dielectric interactions.

Findings

Metal infiltration causes a blue-shift in the (111) photonic stopband.

Greater metal content results in larger blue-shift.

Metal alters the effective dielectric constant of the structure.

Abstract

One of the most appealing aspects of photonic crystal structures is the photonic bandgap created in structures with sufficiently high dielectric contrasts between constituent materials. Understanding how specific photonic crystal structures and their associated stopband positions can selectively interfere with incoming light is vital for implementing these structured dielectrics in a range of optical applications. Metallo-dielectric photonic crystals act to incorporate metal particles into the ordered arrangement of these structures. We examined copper, nickel and gold metal infiltration into polystyrene opals and TiO2 inverse opals. We report a consistent optical phenomena directly associated with the creation of metallo-dielectric photonic crystal structures. More pronounced and numerous diffraction resonances emerge in opal photonic crystals with a metal deposited across the top layer. Common to both opal and inverse opal structures, was a blue-shift in the position of the (111) photonic stopband which increased in magnitude with greater metal content in the structure. We investigate the origin of the photonic stopband blue-shift by variation of the metal content and the placement of metal in the photonic crystal structure. Metal introduced to structured dielectric media tunes the photonic stopband by altering the effective dielectric constant of the photonic crystal.