WGMode : A Matlab toolbox for whispering gallery modes volume computation in spherical optical micro-resonators

Balac, Stéphane

doi:10.1016/j.cpc.2019.05.002

Cited by 18 publications

(9 citation statements)

References 19 publications

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“…1c). WGMs in a microstructure may be analytically investigated in a precise 49,50 or approximate 15,[51][52][53][54][55] manner by using a MATLAB toolbox 56 . Several numerical tools, such as Lumerical, based on the finite-difference time-domain approach, and COMSOL Multiphysics, based on the finite element method, are also usually applied to study WGMs.…”

Section: / 52mentioning

confidence: 99%

Whispering-gallery-mode sensors for biological and physical sensing

Humar

Meserve

et al. 2021

Nat Rev Methods Primers

113

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The term whispering gallery modes (WGMs) was first introduced to describe the curvilinear propagation of sound waves under a cathedral dome. The physical concept has now been generalized to include light waves that are continuously reflected along the closed concave surface of an optical cavity such as a glass microsphere. The circular path of the internally reflected light results in constructive interference and optical resonance, a morphology-dependent resonance that is suitable for interferometric sensing. WGM resonators are miniature micro-interferometers that use the multiple-cavity passes of light for very sensitive measurements at the micro-and nanoscale, including single molecules and ions measurements. This Primer introduces various WGM sensors based on glass microspheres, microtoroids, microcapillaries and silicon microrings. We describe the sensing mechanisms including mode splitting and resonance shift, exceptional-point-enhanced sensing, and optomechanical and optoplasmonic signal transductions. Applications and experimental results cover in-vivo and single-molecule sensing, gyroscopes and microcavity quantum electrodynamics. Data analysis methods and limitations of the WGM techniques are also discussed.Finally, we provide an outlook for molecule, in-vivo and quantum sensing.

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Section: / 52mentioning

confidence: 99%

Whispering-gallery-mode sensors for biological and physical sensing

Humar

Meserve

et al. 2021

Nat Rev Methods Primers

113

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“…The calculation uses electrons accelerated to 200 keV, locally interacting with a WGM in a 2 µm sphere, having a vacuum wavelength of = 806 , which was found to be the mode closest to the laser wavelength using the WGMode toolbox 50 . Furthermore, the WGMode toolbox was used to calculate the component of the electric field on the equatorial plane, from which the PINEMrelevant field in space and time was calculated by adding the temporal and azimuthal phase ( ℓ ) .…”

Section: Simulation Details Of the Pinem Map Fig 2cmentioning

confidence: 99%

“…3b). The wavelength of the resonances was calculated by the WGMode package 50 , and the relative strength of each of the resonances was based on the maximal field components, , of the different modes. The TM modes are maximal at the center, and the TE mode at a slightly shifted position compared with the plane of circumference (see red and blue colormaps on Fig.…”

Section: Simulation Details Of the Pinem Map Fig 2cmentioning

confidence: 99%

Controlling Free Electrons with Optical Whispering-Gallery Modes

Kfir

Lourenço-Martins

Storeck

et al. 2020

Conference on Lasers and Electro-Optics

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Free-electron beams serve as uniquely versatile probes of microscopic structure and composition 1,2 , and have repeatedly revolutionized atomic-scale imaging, from solid-state physics to structural biology [3][4][5] . Over the past decade, the manipulation and interaction of electrons with optical fields has seen significant progress, enabling novel imaging methods 6 , schemes of near-field electron acceleration 7,8 , and culminating in 4D microscopy techniques with both high temporal and spatial resolution 9,10 . However, weak coupling strengths of electron beams to optical excitations 11,12 are a standing issue for existing and emerging applications of optical free-electron control. Here, we demonstrate phase matched near-field coupling of a free-electron beam to optical whispering gallery modes of dielectric microresonators. The cavity-enhanced interaction with these optically excited modes imprints a strong phase modulation on co-propagating electrons, which leads to electron-energy sidebands up to hundreds of photon orders and a spectral broadening of 700 eV. Mapping the near-field interaction with ultrashort electron pulses in space and time, we trace the temporal ring-down of the microresonator following a femtosecond excitation and observe the cavity's resonant spectral response. Resonantly enhancing the coupling of electrons and light via optical cavities, with efficient injection and extraction, can open up novel applications such as continuous-wave acceleration, attosecond structuring, and real-time all-optical electron detection.

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“…Including the local thermal effect, the average value ⟨ Δλ ⟩ of resonance wavelength shifts induced by single protein molecules binding within the plasmon-enhanced near field (aka plasmonic hotspot) of the optoplasmonic sensor is formulated as (see Methods) with the effective mode volume V eff of WGM, the excess polarizability α ex and absorption cross-section σ abs of the protein, the refractive index n w ( T ) of water at the temperature T , the water’s thermal conductivity k con (in units of W m -1 K -1 ), the effective volume of the heated water V w , and the effective heat transferring length ξ . It should be noted that unlike the conventional definition of the mode volume of WGM (35), V eff here is defined based on the local light intensity at the nanorod’s hotspot (see Supplementary) and it has already included the LSPR-induced enhancement of the local electric-field intensity of the gold nanorod. The left-hand side of Eq.…”

Section: Introductionmentioning

confidence: 99%

Thermo-optoplasmonic single-molecule sensing on optical microcavities

Toropov,

Houghton,

et al. 2023

Preprint

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Whispering-gallery-mode (WGM) resonators are powerful instruments for single-molecule sensing in biological and biochemical investigations. WGM sensors leveraged by plasmonic nanostructures, known as optoplasmonic sensors, provide unprecedented sensitivity down to single atomic ions. In this article, we describe that the response of optoplasmonic sensors upon the attachment of single protein molecules strongly depends on the intensity of WGM. At low intensity, protein binding causes red shifts of WGM resonance wavelengths, known as the reactive sensing mechanism. By contrast, blue shifts are obtained at high intensities, which we explain as thermo-optoplasmonic (TOP) sensing, where molecules transform absorbed WGM radiation into heat. To support our conclusions, we experimentally investigated seven molecules and complexes; we observed blue shifts for dye molecules, amino acids and anomalous absorption of enzymes in the near-infrared spectral region. As an example of application, we propose a physical model of TOP sensing that can be used for the development of single-molecule absorption spectrometers.Significance StatementA notable contribution to the optical detection of single molecules has been brought about by using optical microcavities, specifically whispering-gallery-mode resonators that combine optical and plasmon resonances for the most sensitive single-molecule and ion detection. Adding absorption measurements to a single-molecule technique that operates in an aqueous solution would provide powerful new detection capabilities for sensing the properties of single molecules. We demonstrate here, for the first time, the detection of absorption cross-sections of protein molecules on optoplasmonic microcavities and validate the technique with seven different molecules and complexes. A proof-of-concept for single-molecule optoplasmonic absorption spectrometers is presented, based on a thermo-optoplasmonic sensing mechanism.

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WGMode : A Matlab toolbox for whispering gallery modes volume computation in spherical optical micro-resonators

Cited by 18 publications

References 19 publications

Whispering-gallery-mode sensors for biological and physical sensing

Whispering-gallery-mode sensors for biological and physical sensing

Controlling Free Electrons with Optical Whispering-Gallery Modes

Thermo-optoplasmonic single-molecule sensing on optical microcavities

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