Finite-element modeling of spontaneous emission of a quantum emitter at nanoscale proximity to plasmonic waveguides

Abstract

We develop a self-consistent finite element method to study spontaneous emission at nanoscale proximity of plasmonic waveguides. In the model, it is assumed that only one guided mode is dominatingly excited by the quantum emitter. With such one dominating mode assumption, the cross section of the plasmonic waveguide can be arbitrary. We apply our numerical method to calculate the coupling of a quantum emitter to a cylindrical nanowire and a rectangular waveguide, and compare the cylindrical nanowire to previous work valid in quasistatic approximation. The fraction of the energy coupled to the plasmonic mode can be calculated exactly, which can be used to determine the single optical plasmon generation efficiency for a quantum emitter. For a gold nanowire we observe agreement with the quasistatic approximation for radii below 20 nm, but for larger radii the total decay rate is up to 10 times larger. For the rectangular waveguide we estimate an optimized value for the spontaneous emission factor β of up to 80%.

Dissipation-driven generation of two-qubit entanglement mediated by plasmonic waveguides

“…We compute the EM field excited by the dipole source with the finite element method (FEM) 62,63 using commercial software (COMSOL). The point dipole is modeled as a linear harmonic current of length l, intensity I 0 , and orientation given by the unit vector n. The associated dipole moment 63 is d = (iI 0 l/ω)n and, to satisfy the dipole approximation, the length l is kept very short in comparison with the emission wavelength (l = λ/330). To model infinitely long PWs, the spatial domain of interest is properly terminated with perfect matching layers that absorb the outgoing electromagnetic waves with negligible reflection.…”

“…63,64 It is thus customary to express the total decay rate as the sum of those three contributions, γ = γ r + γ nr + γ pl . The photons absorbed in the metal and most photons radiated to vacuum do presumably not contribute to the qubit-qubit coupling.…”

Internal quantum efficiency enhancement of GaInN/GaN quantum-well structures using Ag nanoparticles

“…Recent progress in nanophotonics and nanotechnology opens possibilities of engineering LDOS at nanometer scale and at highly advanced levels to achieve directional emission or enhanced light-matter interaction. [7][8][9][10][11][12][13][14] Such a nanophotonic approach has been applied to light emitting devices. [15][16][17][18][19][20][21][22]24,25 The rationale behind is that the transfer of energy from carriers in GaInN QW into localized optical plasmon supported by the metallic nanostructures will create an a afad@fotonik.dtu.…”

Linearly Polarized, Single-Mode Spontaneous Emission in a Photonic Nanowire

“…1, k has been calculated numerically using a full-vectorial finite element method [17], for a embedded point emitter. When this emitter is located on the wire axis, Fig.…”