Free‐space coupling of nanoantennas and whispering‐gallery microcavities with narrowed linewidth and enhanced sensitivity

Gu, Fuxing; Zhang, Li; Zhu, Ying; Zeng, Heping

doi:10.1002/lpor.201500137

Cited by 53 publications

(36 citation statements)

References 48 publications

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“…Despite of these efforts, the nonradiative decay from the dipolar plasmonic modes remains serious for small metallic nanostructures which are advantageous for stronger light-matter interaction due to more confined fields [11]. Here we provide the perspective of microcavity-engineered metallic nanostructure system, which is not revealed in previous studies of the hybrid photonic-plasmonic modes [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. The microcavity engineers electromagnetic environment of dipolar plasmonic mode, enhancing its radiation rate and further reducing the Ohmic absorption.…”

mentioning

confidence: 99%

Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances

Peng

Liu²,

et al. 2017

Phys. Rev. Lett.

132

120

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Localized-surface plasmon resonance is of importance in both fundamental and applied physics for the subwavelength confinement of optical field, but realization of quantum coherent processes is confronted with challenges due to strong dissipation. Here we propose to engineer the electromagnetic environment of metallic nanoparticles (MNPs) using optical microcavities. An analytical quantum model is built to describe the MNP-microcavity interaction, revealing the significantly enhanced dipolar radiation and consequentially reduced Ohmic dissipation of the plasmonic modes. As a result, when interacting with a quantum emitter, the microcavity-engineered MNP enhances the quantum yield over 40 folds and the radiative power over one order of magnitude. Moreover, the system can enter the strong coupling regime of cavity quantum electrodynamics, providing a promising platform for the study of plasmonic quantum electrodynamics, quantum information processing, precise sensing and spectroscopy.Metallic nanostructures confine light on the subwavelength scale due to the collective excitation of electrons known as localized-surface plasmon resonances (LSPRs). Ultrasmall mode volumes of the plasmonic resonances down to cubic nanometers make them a powerful platform for fundamental studies and novel applications, such as spaser [1,2], superlens [3] and quantum plasmonics [4,5]. An emerging field is to study the nanoscale light-matter interaction between plasmonic mode and few or even single quantum emitters (e.g., atoms, molecules or quantum dots, etc). For example, in the weak coupling regime LSPRs are widely used to enhance fluorescence [6][7][8] and Raman scattering [9][10][11] and to achieve unidirectional emission [12]; in the strong coupling regime the coherent hybridizations between plasmonic resonances and quantum emitters have also been investigated both theoretically [13][14][15][16][17][18] and experimentally [19][20][21][22][23][24][25].Two approaches have been taken to achieve singleemitter strong coupling -lowering the mode volumes and suppressing the dissipation. The former typically requires ultra-fine geometries with nanometer or even subnanometer precision [20,25], posing challenges on fabricating metallic structures and positioning individual quantum emitters. For the latter, the dipolar plasmonic modes dissipates through both radiation and Ohmic absorption, while the multipole modes are purely absorptive [26]. A better coherence can be achieved by reducing the excitation of multipole modes or enhancing the excitation of dipolar modes. Thus, efforts have been made to tailor the geometry of the metallic nanostructures, for example, elongating a metallic nanoparticle (MNP) to separate the dipolar and multipole resonances [27], and forming dimer or arrays to obtain stronger coupling of a certain dipolar mode [28]. An alternative approach is cancelling the coupling between the emitters and the multipole modes with emitters homogeneously distributed around the metallic structure [29]. Despite of these efforts, the ...

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mentioning

confidence: 99%

Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances

Peng

Liu²,

et al. 2017

Phys. Rev. Lett.

132

120

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“…Epoxy resin (refractive index n ∼ 1.53) was added to the solvated R6G solution, and the weight ratio of epoxy resin and trichloromethane solution was about (10:2). A microdroplet of R6G-doped epoxy resin solution was picked up using a silica fiber taper with a sharp tip to touch a silica microfiber, which was suspended across a glass channel with a width of ∼500 μm [27][28][29]. Immediately the fiber taper was drawn back.…”

Section: Experiments and Operation Principlementioning

confidence: 99%

Single-mode lasing via loss engineering in fiber-taper-coupled polymer bottle microresonators

Xie

Fang

et al. 2017

Photon. Res.

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Due to the lack of mode selection capability, single whispering-gallery-mode (WGM) lasing is a challenge to achieve. In bottle microresonators, the highly nondegenerated WGMs are spatially well-separated along the long-axis direction and provide mode selection according to their axial mode numbers. In this work, we use a loss-engineering approach to suppress the higher-order WGMs and demonstrate single-mode lasing emission in small polymer bottle microresonators. The fiber tapers are not only used to couple pump light into the bottle microresonators to excite the WGMs but also to bring optical losses that are induced from the diameter mismatch between fiber tapers and microresonators. By adjusting the coupling positions, the diameters of fiber tapers, and the coupling angles, single fundamental-mode lasing is efficiently generated with side-mode suppression factors over 15 dB. Our loss-engineering approach is convenient just by moving the fiber taper and may find promising applications in miniature tunable single-mode lasers and sensors.

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“…Nanoparticle or LSPR sensors show good potential for faster response times [5,6]. However, the broad spectral response of LSPR-based hydrogen sensors arises as an issue, which, later on, led the researchers to reduce the linewidth with the help of a whispering gallery mode cavity [7], and to develop highly sensitive hybrid sensors such as using Pd with a good plasmonic metal [8,9]. For example, Alivisatos and co-workers have demonstrated highly sensitive hydrogen sensors by placing Pd nanoparticles close to the sharp corners of nanoantennas [10].…”

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confidence: 99%

Perfectly absorbing ultra thin interference coatings for hydrogen sensing

et al. 2016

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Here we numerically demonstrate a straightforward method for optical detection of hydrogen gas by means of absorption reduction and colorimetric indication. A perfectly absorbing metal-insulator-metal (MIM) thin film interference structure is constructed using a silver metal back reflector, silicon dioxide insulator, and palladium as the upper metal layer and hydrogen catalyst. The thickness of silicon dioxide allows the maximizing of the electric field intensity at the Air∕SiO 2 interface at the quarter wavelengths and enabling perfect absorption with the help of highly absorptive palladium thin film ∼7 nm. While the exposure of the MIM structure to H 2 moderately increases reflection, the relative intensity contrast due to formation of metal hydride is extensive. By modifying the insulator film thickness and hence the spectral absorption, the color is tuned and eyevisible results are obtained. Hydrogen H 2 sensing requires development of highly sensitive, reliable, and short response-time sensors due to its use in critical applications such as fuel-cells, pharmaceuticals, and petroleum and chemical production. Palladium (Pd) can absorb H 2 upon exposure and transform into palladium hydride PdH x , and the optical and electrical properties of Pd metal are changed by such transformation [1]. Recent advancements in plasmonic research and nanofabrication techniques led the development of surface and localized surface plasmon-based (LSPR) hydrogen sensors using Pd [2][3][4]. Nanoparticle or LSPR sensors show good potential for faster response times [5,6]. However, the broad spectral response of LSPR-based hydrogen sensors arises as an issue, which, later on, led the researchers to reduce the linewidth with the help of a whispering gallery mode cavity [7], and to develop highly sensitive hybrid sensors such as using Pd with a good plasmonic metal [8,9]. For example, Alivisatos and co-workers have demonstrated highly sensitive hydrogen sensors by placing Pd nanoparticles close to the sharp corners of nanoantennas [10].Such sensing mechanisms are based on probing of the scattering properties of nanoantenna-Pd nanoparticle structure, rather than the direct probing of scattering properties of Pd nanoparticles that shows small wavelength shifts upon hydrogen exposure. Other important plasmon-based hydrogen sensing mechanism is based on plasmonic-perfect absorbers [11][12][13], and single crystal Pd and its alloy-coated nanowires [14,15]. The motivation behind the absorbance-based sensors is to minimize the requirement for the bulky optical setups, expensive light sources, and spectrometers by only probing the scattered light intensity at perfect-absorption wavelength. Moreover, some of the recent studies report the visual detection of hydrogen by using thin film optical coatings to circumvent the problems of hydrogen sensors based on electrical readout [16,17]. Despite the demonstration of visual detection of H 2 , the thin film structure did not take full advantage of the lossy nature of Pd films. In this study, we demo...

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Free‐space coupling of nanoantennas and whispering‐gallery microcavities with narrowed linewidth and enhanced sensitivity

Cited by 53 publications

References 48 publications

Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances

Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances

Single-mode lasing via loss engineering in fiber-taper-coupled polymer bottle microresonators

Perfectly absorbing ultra thin interference coatings for hydrogen sensing

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