Signature of a three-dimensional photonic band gap observed on silicon inverse woodpile photonic crystals

TL;DR

This study demonstrates the existence of a broad three-dimensional photonic band gap in silicon inverse woodpile photonic crystals through near-infrared reflectivity measurements, supported by theoretical calculations.

Contribution

First experimental observation of a three-dimensional photonic band gap in silicon inverse woodpile crystals using polarization-resolved reflectivity spectroscopy.

Findings

High reflectivity peaks up to 67% observed

Broad photonic band gap with up to 16% bandwidth identified

Spectral signatures confirmed by bandstructure calculations

Abstract

We have studied the reflectivity of CMOS-compatible three-dimensional silicon inverse woodpile photonic crystals at near-infrared frequencies. Polarization-resolved reflectivity spectra were obtained from two orthogonal crystal surfaces corresponding to 1.88 pi sr solid angle. The spectra reveal broad peaks with high reflectivity up to 67 % that are independent of the spatial position on the crystals. The spectrally overlapping reflectivity peaks for all directions and polarizations form the signature of a broad photonic band gap with a relative bandwidth up to 16 %. This signature is supported with stopgaps in plane wave bandstructure calculations and with the frequency region of the expected band gap.