Looking inside three-dimensional (3D) silicon photonic band gap crystals

TL;DR

This study uses 3D x-ray holotomography to analyze silicon photonic band gap crystals, revealing detailed internal structure and minor distortions, demonstrating the technique's potential for future optical metamaterial research.

Contribution

First application of 3D x-ray holotomography to silicon photonic crystals, providing detailed internal density maps and insights into fabrication accuracy.

Findings

Structural design is well-realized in the fabricated crystal

Detected slight shear-distortion of the cubic structure

Demonstrated potential of 3D tomography for optical metamaterials

Abstract

We have performed an x-ray holotomography study of a three-dimensional (3D) photonic band gap crystal. The crystals was made from silicon by CMOS-compatible methods. We manage to obtain the 3D material density throughout the fabricated crystal. We observe that the structural design is for most aspects well-realized by the fabricated nanostructure. One peculiar feature is a slight shear-distortion of the cubic crystal structure. We conclude that 3D X-ray tomography has great potential to solve many future questions on optical metamaterials.