Yuntian Chen

Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while measuring its lifetime. We demonstrate the method by imaging the enhancement of the local density of optical states around metal nanowires. By nanopositioning, the decay rate of a pointlike source of fluorescence can be reversibly and repeatedly changed by a factor of 2 by coupling it to the guided plasmonic mode of the wire.

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

We develop a self-consistent finite-element method to quantitatively study spontaneous emission from emitters in nanoscale proximity of plasmonic waveguides. In the model, it is assumed that only one guided mode is dominatingly excited by the quantum emitter, while the cross section of the plasmonic waveguide can be arbitrary. The fraction of the energy coupled to the plasmonic mode can be calculated exactly, which can be used to determine the efficiency with which single optical plasmons are generated. We apply our numerical method to calculate the coupling of a quantum emitter to a cylindrical metallic nanowire and a square metallic waveguide, and compare the cylindrical metallic nanowire with previous work that employs quasistatic approximation. For the cylindrical metallic nanowire we observe good agreement with the quasistatic approximation for radii below 10 nm, but for increasing radius the spontaneous emission

Design of annular photonic crystal slabs

\ensuremath{\beta}

Spontaneous decay of a single quantum dot coupled to a metallic slot waveguide in the presence of leaky plasmonic modes

factor and the plasmonic decay rate deviate substantially, by factors of up to 5\char21{}10 for a radius of

Coherent single-photon absorption by single emitters coupled to one-dimensional nanophotonic waveguides

\ensuremath{\sim}100\text{ }\text{nm}

Dynamically reconfigurable directionality of plasmon-based single photon sources

, from the values obtained in the quasistatic approximation. We also show that the quasistatic approximation is typically valid when the radius is less than the skin depth of the metals at optical frequencies. For the square metallic waveguide we estimate an optimized value for the spontaneous emission

General coupled mode theory in non-Hermitian waveguides

\ensuremath{\beta}

Coupled mode theory in non-Hermitian optical cavities

factor up to 80%.

Elimination of polarization degeneracy in circularly symmetric bianisotropic waveguides: a decoupled case

We present the design of realistic annular photonic-crystal (APC) structures of finite thickness aiming to obtain a complete photonic bandgap (PBG). The APC is composed of dielectric rods and circular air holes in a triangular lattice such that each rod is centered within each hole. The optical and geometrical values of the structure are studied, and the interplay between various design parameters is highlighted. The coupled role of the inner-dielectric-rod radius, material types, and slab thickness is investigated. It is shown that the slab thickness is vital to obtain a complete photonic bandgap below the light line, and the specific value of the inner-dielectric-rod radius to sustain the maximum PBG if the hole radius is fixed at proper value is found.

Fourier finite element modeling of light emission in waveguides: 2.5-dimensional FEM approach

We numerically investigate the coupling efficiency of a single self-assembled quantum dot to a metallic slot waveguide in the presence of leaky plasmonic modes. Leaky plasmonic modes refer to radiation modes with plasmonic features, resulting from the inhomogeneity of the dielectric environment in which the metallic slot waveguide is embedded. Compared to the ideal case of a homogenous dielectric environment, the coupling efficiency of an emitter to a metallic slot waveguide is significantly reduced. We attribute the reduction to the coupling to leaky plasmonic modes. By increasing the refractive index of the coating layer to minimize the impacts from the leaky plasmonic modes, we find that the coupling efficiency of the quantum dot to the single mode supported by the metallic slot waveguide can be enhanced by more than a factor 2.