Flat Dielectric Grating Reflectors with High Focusing Power

TL;DR

This paper introduces non-periodic dielectric grating mirrors that enable full phase front control of reflected light while maintaining high reflectivity, offering new opportunities for compact optical devices.

Contribution

It demonstrates that non-periodic patterning of dielectric gratings can control phase fronts, a feature not possible with traditional DBR mirrors.

Findings

Non-periodic dielectric gratings achieve high reflectivity.

Patterning enables full phase front control.

Potential applications in laser cavities and optical read/write devices.

Abstract

Sub-wavelength dielectric gratings (SWG) have emerged recently as a promising alternative to distributed-Bragg-reflection (DBR) dielectric stacks for broadband, high-reflectivity filtering applications. A SWG structure composed of a single dielectric layer with the appropriate patterning can sometimes perform as well as thirty or forty dielectric DBR layers, while providing new functionalities such as polarization control and near-field amplification. In this paper, we introduce a remarkable property of grating mirrors that cannot be realized by their DBR counterpart: we show that a non-periodic patterning of the grating surface can give full control over the phase front of reflected light while maintaining a high reflectivity. This new feature of dielectric gratings could have a substantial impact on a number of applications that depend on low-cost, compact optical components, from laser cavities to CD/DVD read/write heads.