Investigation of the Purcell effect in photonic crystal cavities with a 3D Finite Element Maxwell Solver

Abstract

Photonic crystal cavities facilitate novel applications demanding the efficient emission of incoherent light. This unique property arises when combining a relatively high quality factor of the cavity modes with a tight spatial constriction of the modes. While spontaneous emission is desired in these applications the stimulated emission must be kept low. A measure for the spontaneous emission enhancement is the local density of optical states (LDOS). Due to the complicated three dimensional geometry of photonic crystal cavities the LDOS quantity has to be computed numerically. In this work, we present the computation of the LDOS by means of a 3D Finite Element (FE) Maxwell Solver. The solver applies a sophisticated symmetry handling to reduce the problem size and provides perfectly matched layers to simulate open boundaries. Different photonic crystal cavity designs have been investigated for their spontaneous emission enhancement by means of this FE solver. The simulation results have been compared to photoluminescence characterizations of fabricated cavities. The excellent agreement of simulations and characterizations results confirms the performance and the accuracy of the 3D FE Maxwell Solver.

Near-field mapping of quantum dot emission from single-photonic crystal cavity modes

“…Fig. 2(a) shows the simulated spectra obtained by a spatial average of the spectral spontaneous emission enhancement and subsequent filtering to simulate the effect of the limited resolution of the spectral analysis [7]. The simulated curve reproduces the experimental spectrum with high accuracy: all the resonances are well distinguishable and also the relative spectral distance between the peaks is in perfect agreement with the near-field data.…”

“…These PL intensity maps are usually assumed to reproduce, at first approximation, the spatial distribution of the electric field intensity [5,6]. The spectral spontaneous emission enhancement and the near-field have been simulated with a 3D finite element Maxwell solver [7,8]. Fig.…”

Computational electromagnetics for nanowire solar cells

“…Regarding nanostructured solar cells, such a statement cannot be made a-priori as nanostructures are known to exhibit LDOS enhancement. This effect is commonly called Purcell effect [128,129]. In fact, nanostructures are under intense research dedicated to improving the efficiency of light emitting diodes (LEDs), which benefit from an enhancement of radiative recombination compared to the non-radiative pathways.…”

“…The LDOS can be computed either via the dyadic Green's function [137] or through a complete modal expansion [129,138]. The computation via the dyadic Green's function requires to probe the nanostructure with Hertzian dipoles, solving the SP for every position.…”

Inhibition of light emission in a 2.5D photonic structure

“…For example, using micro pillars grown on a mirror leads to an inhibition factor of 16 for dipole emitters orthogonal to the nano wire [10] but the effect was dependent on the position of the emitters (typically a quantum dot) in the plane where they have been grown. Cavities in 2D PhC was also theoretically studied, such as H1 cavities [11] exhibiting huge inhibition (>1000) but for specific wavelength and location of the dipole. Tamm plasmon structures were also used leading to an inhibition Purcell factor of 40 (the highest published experimental value to our knowledge) [12] but for a single emitter accurately located at a field intensity node.…”