Optical properties of circular Bragg gratings with labyrinth geometry to enable electrical contacts

TL;DR

This study explores how labyrinth-like connection designs in circular Bragg gratings influence optical confinement and device performance, combining experimental and simulation approaches to optimize structure for better mode confinement and Purcell enhancement.

Contribution

It introduces a novel labyrinth geometry for electrical contacts in circular Bragg gratings and systematically evaluates its impact on optical properties through experiments and simulations.

Findings

Rotating connections enhances mode confinement and Purcell factor.

Labyrinth geometries reduce asymmetries and improve far-field patterns.

Optimal connection arrangements depend on symmetry and width.

Abstract

We present an optical study of various device designs for electrically contactable circular Bragg grating cavities in labyrinth geometries. To create an electrical connection between the central disk and the surrounding membrane, which are separated through air gaps, we introduce connections between the adjacent rings. We propose to rotate these connections, creating a labyrinth like structure, to disable waveguiding and keep the mode confinement. To investigate how different arrangement and size of the connections affect the optical properties and to find the optimal design, six different layouts with either 3-fold or 4-fold symmetry and one with 2-fold symmetry are investigated experimentally and by numerical simulations. Reflectivity measurements and simulations show that rotating the connections improves the mode confinement, far-field pattern and Purcell factor compared to layouts with connections arranged in straight lines. We compare results between different layouts for different connection widths and perform polarization resolved measurements to investigate whether the connections create asymmetries in the photonic confinement that would impede the performance of the device.