arXiv subjects

Philip Trøst Kristensen

Publications and source records attributed to Philip Trøst Kristensen.

23 records · Page 2Linked to original sources

arXiv2013

Modes and Mode Volumes of Leaky Optical Cavities and Plasmonic Nanoresonators

Electromagnetic cavity modes in photonic and plasmonic resonators offer rich and attractive regimes for tailoring the properties of light-matter interactions. Yet there is a disturbing lack of a precise definition for what constitutes a cavity mode, and as a result their mathematical properties remain largely unspecified. The lack of a definition is evidenced in part by the diverse nomenclature at use - "resonance", "leaky mode", "quasimode", to name but a few - suggesting that the dissipative nature of cavity modes somehow makes them different from other modes, but an explicit distinction is rarely made. This perspective article aims to introduce the reader to some of the subtleties and working definitions that can be rigorously applied when describing the modal properties of leaky optical cavities and plasmonic nanoresonators. We describe some recent development in the field, including {calculation methods for quasinormal modes of both photonic and plasmonic resonators and the concept of a generalized effective mode volume, and we} illustrate the theory with several representative cavity structures from the fields of photonic crystals and nanoplasmonics.

cond-mat.mes-hall↗

arXiv2013

Three-dimensional integral equation approach to light scattering, extinction cross sections, local density of states and quasinormal modes

We present a numerical formalism for solving the Lippmann-Schwinger equation for the electric field in three dimensions. The formalism may be applied to scatterers of different shapes and embedded in different background media, and we develop it in detail for the specific case of spherical scatterers in a homogeneous background medium. In addition, we show how several physically important quantities may readily be calculated with the formalism. These quantities include the extinction cross section, the total Green's tensor, the projected local density of states and the Purcell factor as well as the quasinormal modes of leaky resonators with the associated resonance frequencies and quality factors. We demonstrate the calculations for the well-known plasmonic dimer consisting of two silver nanoparticles and thus illustrate the versatility of the formalism for use in modeling of advanced nanophotonic devices.

physics.optics↗

arXiv2011

Spontaneous Emission Spectra and Quantum Light-Matter Interactions from a Strongly-Coupled Quantum Dot Metal-Nanoparticle System

We investigate the quantum optical properties of a single photon emitter coupled to a finite-size metal nanoparticle using a photon Green function technique that rigorously quantizes the electromagnetic fields. We first obtain pronounced Purcell factors and photonic Lamb shifts for both a 7-nm and 20-nm radius metal nanoparticle, without adopting a dipole approximation. We then consider a quantum-dot photon emitter positioned sufficiently near to the metal nanoparticle so that the strong coupling regime is possible. Accounting for non-dipole interactions, quenching, and photon transport from the dot to the detector, we demonstrate that the strong coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four peaks anticrossing, which survives in spite of significant non-radiative decays. We discuss the emitted light spectrum and the effects of quenching for two different dipole polarizations.

cond-mat.mes-hall↗

arXiv2011

Effective mode volumes and Purcell factors for leaky optical cavities

We show that for optical cavities with any finite dissipation, the term "cavity mode" should be understood as a solution to the Helmholtz equation with outgoing wave boundary conditions. This choice of boundary condition renders the problem non-Hermitian, and we demonstrate that the common definition of an effective mode volume is ambiguous and not applicable. Instead, we propose an alternative effective mode volume which can be easily evaluated based on the mode calculation methods typically applied in the literature. This corrected mode volume is directly applicable to a much wider range of physical systems, allowing one to compute the Purcell effect and other interesting optical phenomena in a rigorous and unambiguous way.

math-ph↗

arXiv2009

Frequency dependence of the radiative decay rate of excitons in self-assembled quantum dots: experiment and theory

We analyze time-resolved spontaneous emission from excitons confined in self-assembled $\mathrm{InAs}$ quantum dots placed at various distances to a semiconductor-air interface. The modification of the local density of optical states due to the proximity of the interface enables unambiguous determination of the radiative and non-radiative decay rates of the excitons. From measurements at various emission energies we obtain the frequency dependence of the radiative decay rate, which is only revealed due to the separation of the radiative and non-radiative parts. It contains detailed information about the dependence of the exciton wavefunction on quantum dot size. The experimental results are compared to the quantum optics theory of a solid state emitter in an inhomogeneous environment. Using this model, we extract the frequency dependence of the overlap between the electron and hole wavefunctions. We furthermore discuss three models of quantum dot strain and compare the measured wavefunction overlap to these models. The observed frequency dependence of the wavefunction overlap can be understood qualitatively in terms of the different compressibility of electrons and holes originating from their different effective masses.

cond-mat.other↗