# Monolithic semiconductor hemispherical micro cavities for efficient single photon extraction

## TL;DR

This paper introduces a monolithic hemispherical microcavity design that enhances photon extraction efficiency from embedded quantum emitters, with practical fabrication and characterization demonstrating its potential for quantum photonics.

## Contribution

It presents a novel monolithic hemispherical microcavity design with tunable finesse, suppression of higher order modes, and practical fabrication for improved single-photon emission.

## Key findings

- Efficient photon extraction into fundamental Gaussian mode.
- Design flexibility with adjustable finesse.
- Successful fabrication and optical characterization.

## Abstract

We present a monolithic semiconductor microcavity design for enhanced light-matter interaction and photon extraction efficiency of an embedded quantum emitter such as a quantum dot or color center. The microcavity is a hemispherical Fabry-Perot design consisting of a planar back mirror and a top curved mirror. Higher order modes are suppressed in the structure by reducing the height of the curved mirror, leading to efficient photon extraction into a fundamental mode with a Gaussian far-field radiation pattern. The cavity finesse can be varied easily by changing the reflectivity of the mirrors and we consider two specific cases: a low-finesse structure for enhanced broad band photon extraction from self-assembled quantum dots and a moderate-finesse cavity for enhanced extraction of single photons from the zero-phonon line of color centers in diamond. We also consider the impact of structural imperfections on the cavity performance. Finally, we present the fabrication and optical characterisation of monolithic GaAs hemispherical microcavities.