Numerical investigation of plasmonic photonic hybrid whispering gallery modes
18 Apr 2017-pp 51-52
TL;DR: In this paper, the hybrid plasmonic photonic WGM modes of a metal coated microsphere resonator were numerically investigated and a three-layer structure with a silica micro-sphere core, a 30 nm silver intermediate layer and an outer polymer layer was proposed.
Abstract: The hybrid plasmonic photonic WGM modes of a metal coated microsphere resonator are numerically investigated The proposed geometry consists of a three-layer structure with a silica microsphere core, a 30 nm silver intermediate layer and an outer polymer layer It has been shown that the proposed geometry supports hybrid resonances with moderately high Q-factor and low mode volume The properties of the hybrid modes can be tuned by varying the thickness of the polymer layer
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01 Apr 2020
TL;DR: In this article, the effect of octopod and octahedral shaped gold nanoparticles (AuNPs) on the radiative rate of rhodamine B (RB) doped microspheres was investigated.
Abstract: Whispering gallery modes (WGMs) occur due to total internal reflection in symmetric dielectric structures. These modes have high quality (Q) factor and low mode volume (Veff). Photoluminescence (PL) of an emitter when coupled with WGMs leads to the modification in the radiative rate of the emitter. This effect on the radiative rate is known as Purcell effect. Purcell factor (FP) is proportional to Q/Veff of the cavity. Localized surface plasmon resonance (LSPR) of metal nanoparticles (NPs) can be used along with the WGMs of the microcavity to have a combined LSPR-WGM hybrid system. LSPR depends on the shape and size of the NPs which can affect FP of the microcavity. In this work, we report the effect of octopod and octahedral shaped gold nanoparticles (AuNPs) on the radiative rate of rhodamine B (RB) doped microspheres. FP values of smaller than unity have been observed indicating the inhibition of the radiative rate in the microcavity.
1 citations
References
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TL;DR: In this paper, the optical constants for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV.
Abstract: The optical constants $n$ and $k$ were obtained for the noble metals (copper, silver, and gold) from reflection and transmission measurements on vacuum-evaporated thin films at room temperature, in the spectral range 0.5-6.5 eV. The film-thickness range was 185-500 \AA{}. Three optical measurements were inverted to obtain the film thickness $d$ as well as $n$ and $k$. The estimated error in $d$ was \ifmmode\pm\else\textpm\fi{} 2 \AA{}, and that in $n$, $k$ was less than 0.02 over most of the spectral range. The results in the film-thickness range 250-500 \AA{} were independent of thickness, and were unchanged after vacuum annealing or aging in air. The free-electron optical effective masses and relaxation times derived from the results in the near infrared agree satisfactorily with previous values. The interband contribution to the imaginary part of the dielectric constant was obtained by subtracting the free-electron contribution. Some recent theoretical calculations are compared with the results for copper and gold. In addition, some other recent experiments are critically compared with our results.
17,509 citations
"Numerical investigation of plasmoni..." refers background in this paper
...The dielectric constant of the silver was taken from Johnson and Christy [5]....
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TL;DR: In this paper, the orientation of dipole emitters in nanogaps plays a vital role in spontaneous emission enhancement factors of greater than 1,000, the largest observed to date.
Abstract: Plasmonic nanostructures enable spontaneous emission enhancement factors of greater than 1,000 — the largest observed to date. The orientation of dipole emitters in nanogaps plays a vital role.
889 citations
"Numerical investigation of plasmoni..." refers background in this paper
...The mismatch of the WGM resonance frequency and the natural linewidth of the quantum emitter limits the maximum achievable Purcell factor of WGM resonators below 100 [1]....
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...In contrast, plasmonic microcavities with Purcell factor as high as 2000 have been reported [1]....
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TL;DR: A high-Q SPP whispering-gallery microcavity that is made by coating the surface of a high- Q silica microresonator with a thin layer of a noble metal is demonstrated and Q factors of 1,376 ± 65 can be achieved in the near infrared for surface-plasmonic whispering- gallery modes at room temperature.
Abstract: Surface plasmon polaritons (SPPs) are electron density waves excited at the interfaces between metals and dielectric materials (1). Owing to their highly localized electromagnetic fields, they may be used for the transport and manipulation of photons on subwavelength scales (2-9). In particular, plasmonic resonant cavities represent an application that could exploit this field compression to create ultrasmall-mode-volume devices. A key figure of merit in this regard is the ratio of cavity quality factor, Q (related to the dissipation rate of photons confined to the cavity), to cavity mode volume, V (refs 10, 11). However, plasmonic cavity Q factors have so far been limited to values less than 100 both for visible and near-infrared wavelengths (12-16). Significantly, such values are far below the theoretically achievable Q factors for plasmonic resonant structures. Here we demonstrate a high-Q SPP whispering-gallery microcavity that is made by coating the surface of a high-Q silica microresonator with a thin layer of a noble metal. Using this structure, Q factors of 1,376 ± 65 can be achieved in the near infrared for surface-plasmonic whispering-gallery modes at room temperature. This nearly ideal value, which is close to the theoretical metal-loss-limited Q factor, is attributed to the suppression and minimization of radiation and scattering losses that are made possible by the geometrical structure and the fabrication method. The SPP eigenmodes, as well as the dielectric eigenmodes, are confined within the whispering-gallery microcavity and accessed evanescently using a single strand of low-loss, tapered optical waveguide (17, 18). This coupling scheme provides a convenient way of selectively exciting and probing confined SPP eigenmodes. Up to 49.7 per cent of input power is coupled by phase-matching control between the microcavity SPP and the tapered fibre eigenmodes.
464 citations
"Numerical investigation of plasmoni..." refers background in this paper
...Plasmonic WGM resonators such a metal-coated disc resonators [2] and microbottle resonators [3] have a metallic outer layer which makes the coupling of the light in and out of the cavity difficult....
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TL;DR: In this article, a software package for solving partial-differential-equations (PDEs), as based on the finite-element method, can be configured to efficiently calculate the frequencies and fields of the whispering-gallery (WG) modes of axisymmetric dielectric resonators.
Abstract: This paper explains how a popular commercially available software package for solving partial-differential-equations (PDEs), as based on the finite-element method, can be configured to efficiently calculate the frequencies and fields of the whispering-gallery (WG) modes of axisymmetric dielectric resonators. The approach is traceable; it exploits the PDE-solver's ability to accept the definition of solutions to Maxwell's equations in so-called weak form. Associated expressions and methods for estimating a WG mode's volume, filling factor(s), and in the case of closed (open) resonators, its wall (radiation) loss, are provided. As no transverse approximation is imposed, the approach remains accurate even for quasi-transverse-magnetic/electric modes of low finite azimuthal mode order. The approach's generality and utility are demonstrated by modeling several nontrivial structures, i.e., 1) two different optical microcavities (one toroidal made of silica, the other an AlGaAs microdisk), 2) a third-order sapphire:air Bragg cavity, and 3) two different cryogenic sapphire WG-mode resonators; both 2) and 3) operate in the microwave X-band. By fitting one of 3) to a set of measured resonance frequencies, the dielectric constants of sapphire at liquid-helium temperature have been estimated.
286 citations
"Numerical investigation of plasmoni..." refers methods in this paper
...Computational method The axisym method [4] implemented in Comsol Multiphysics was used to estimate the resonance frequency and mode field distributions of the hybrid modes....
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TL;DR: It is experimentally demonstrated that hybrid plasmon-photon modes exist in a silver-coated glass bottle resonator and that the rhodamine 800 photoluminescence excites hybrid plaison modes in such a bottle resonators, which provide a plAsmon-type field enhancement at the outer silver surface and exhibit quality factors as high as 1000.
Abstract: We experimentally demonstrate that hybrid plasmon-photon modes exist in a silver-coated glass bottle resonator. The bottle resonator is realized in a glass fiber with a smoothly varying diameter, which is subsequently coated with a rhodamine 800-dye doped acryl-glass layer and a 30 nm thick silver layer. We show by means of photoluminescence experiments supported by electromagnetic simulations that the rhodamine 800 photoluminescence excites hybrid plasmon-photon modes in such a bottle resonator, which provide a plasmon-type field enhancement at the outer silver surface and exhibit quality factors as high as 1000.
33 citations
"Numerical investigation of plasmoni..." refers background in this paper
...Plasmonic WGM resonators such a metal-coated disc resonators [2] and microbottle resonators [3] have a metallic outer layer which makes the coupling of the light in and out of the cavity difficult....
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