Photonic hyperuniform networks by silicon double inversion of polymer templates

TL;DR

This paper demonstrates a novel fabrication method for hyperuniform photonic networks using laser writing and silicon inversion, achieving photonic bandgaps in the shortwave infrared with tunable structural parameters.

Contribution

It introduces a direct laser writing and silicon double inversion technique to create hyperuniform photonic networks with controlled optical properties.

Findings

Pronounced photonic bandgap observed at 2.5 μm in the shortwave infrared.

Tunable structural length scale from 2 μm to 1.54 μm shifts the bandgap.

High-quality silicon network structures achieved through the fabrication process.

Abstract

Hyperuniform disordered networks belong to a peculiar class of structured materials predicted to possess partial and complete photonic bandgaps for relatively moderate refractive index contrasts. The practical realization of such photonic designer materials is challenging however, as it requires control over a multi-step fabcrication process on optical length scales. Here we report the direct-laser writing of hyperuniform polymeric templates followed by a silicon double inversion procedure leading to high quality network structures made of polycrystalline silicon. We observe a pronounced gap in the shortwave infrared centered at a wavelength of $\lambda_{\text{Gap}}\simeq $ 2.5 $\mu$m, in nearly quantitative agreement with numerical simulations. In the experiments the typical structural length scale of the seed pattern can be varied between 2 $\mu$m and 1.54 $\mu$m leading to a blue-shift of the gap accompanied by an increase of the silicon volume filling fraction.