High quality factor GaAs microcavity with buried bullseye defects

Abstract

The development of high quality factor solid-state microcavities with low mode volumes has paved the way towards on-chip cavity quantum electrodynamics experiments and the development of high-performance nanophotonic devices. Here, we report on the implementation of a new kind of solid-state vertical microcavity, which allows for confinement of the electromagnetic field in the lateral direction without deep etching. The confinement originates from a local elongation of the cavity layer imprinted in a shallow etch and epitaxial overgrowth technique. We show that it is possible to improve the quality factor of such microcavities by a specific in-plane bullseye geometry consisting of a set of concentric rings with subwavelength dimensions. This design results in a smooth effective lateral photonic potential and therefore in a reduction of lateral scattering losses, which makes it highly appealing for experiments in the framework of exciton-polariton physics demanding tight spatial confinement.

Transfer Matrix Model for Emission Profile Optimization of Radial Gratings

“…We record the mode amplitudes inside a(r in ) and outside a(r out ) of the shell, with r in < r < r out . The total transfer matrix T describing both the scatter as well as the propagation to and from it is then obtained from Equation (1): T(r, q, r out , r in ) = A(r out ) ⋅ A(r in ) −1 = P(r, r out ) ⋅ S(r, q) ⋅ P(r in , r) ( 5 ) Left and right multiplying the inverse of the according propagation matrices P, we can then extract S(r, q). In addition, each shell may emit into free-space when a propagating mode is incident upon it as sketched in Figure 1b, such that the total emitted fields are given by the coherent sum of the fields emitted by all shells combined.…”

“…[1][2][3] Most designs thereby employ a periodic grating design. [1,2,[4][5][6][7][8][9] Transfer matrix models (TMMs) have been used for decades to predict the behavior of flat, stratified optical systems, such as distributed Bragg reflectors (DBRs), subject to plane wave illumination. [10][11][12] Already in the 1990s, TMMs were adapted for radially curved layers with impinging radial propagating waves.…”

“…[19][20][21] Even though both the curved geometry and the results for linear waveguide couplers therefore suggest a non-periodic design for radial Bragg gratings, most publications today still revert to use a plane wave TMM and/or periodic radial structure. [1,2,[4][5][6][7][8][9] The large computational cost of simulating any radial structure using the most common, rectangular, three-dimensional finite difference time domain (FDTD) method hinders the development of non-periodic radial geometries, and thus, their implementation in optical nanostructures. To make optimization feasible, a periodic design is preferred with a small number of free parameters.…”