Resonant Effects in Nanoscale Bowtie Apertures

Ding, Li; Qin, Jin; Guo, Songpo; Liu, Tao; Kinzel, Edward C.; Wang, Liang

doi:10.1038/srep27254

Cited by 11 publications

(10 citation statements)

References 25 publications

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“…The optical responses of plasmonic nanocavities strongly depend on their geometrical design as well as irradiation field parameters such as polarization and excitation wavelength. [ 36,37 ] In particular, the electromagnetic properties of nanocavities are extremely sensitive to morphological fluctuations and subtle changes in the dielectric properties of the cavity contents. [ 19 ] Thus, parameters pertaining to the nanocavity design, such as nanostructure configuration [ 30 ] and cavity gap size, [ 38 ] play important roles in modifying both the near‐field intensity and far‐field radiation of the proposed architectures.…”

Section: Optical Properties Of Plasmonic Nanocavitiesmentioning

confidence: 99%

“…These two distinct modes are highlighted in Figure a that shows simulated transmission spectrum of a bowtie aperture defined in a 200 nm thick silver film on top of a fused silica substrate. [ 36 ] The intensities and resonance wavelengths of both modes strongly depend on the cavity gap size g that is defined in terms of aperture parameters:

g = 2 r (\frac{1}{a} \sqrt{a^{2} - b^{2}} - 1)

, where a is the length, b width, and r ridge radius of the aperture, as illustrated in the inset of Figure 1a. Thus, the cavity mode can be easily tuned by changing one of the nanoaperture parameters.…”

Section: Optical Properties Of Plasmonic Nanocavitiesmentioning

confidence: 99%

“…Reproduced with permission. [ 36 ] Copyright 2016, Springer Nature. b) Schematic illustration and near‐field profiles of a bowtie aperture fabricated in 100 nm thick silver film with cavity gap G = 30 nm, gap length L = 82 nm, arm length a = 150 nm, and arm angle θ = 30°.…”

Section: Optical Properties Of Plasmonic Nanocavitiesmentioning

confidence: 99%

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Novel Plasmonic Nanocavities for Optical Trapping‐Assisted Biosensing Applications

Koya

Cunha

Guo

et al. 2020

Advanced Optical Materials

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However, due to the intrinsic low optical response of small objects, there has been a clear trade-off between the size of a material and its response to light. [5] Recently, plasmonic nanostructures have emerged as leading platforms to enhance the weak optical signals of low dimensional materials including quantum dots (QDs), [6] small molecules, [7,8] and 2D monolayers. [9] The plasmonic enhancement of linear and nonlinear optical processes capitalizes on the near-and far-field properties of metallic (e.g., gold and silver) nanostructures. [10] One of the defining features of plasmonic nanostructures is their potential to confine light into deep subwavelength volumes, which has opened a new door to trap and manipulate dielectric, metallic, and biological nano-objects. [11] Moreover, metallic nanostructures are characterized by their capability to amplify the intensity of optical fields by orders of magnitude. The enhancement of local field intensity is attributed to the resonance of plasmon polaritons arising from the coupling of external electromagnetic fields to the collective oscillations of the conduction electrons. [12] A small perturbation (or change in the refractive index) of the near field zone of plasmonic nanostructures leads to significant shift in the plasmon polariton resonance wavelength, which has important implications for surface-enhanced sensing and spectroscopic applications. [13,14] Thus, for the ad-hoc enhancement of optical Plasmonic nanocavities have proved to confine electromagnetic fields into deep subwavelength volumes, implying their potentials for enhanced optical trapping and sensing of nanoparticles. In this review, the fundamentals and performances of various plasmonic nanocavity geometries are explored with specific emphasis on trapping and detection of small molecules and single nanoparticles. These applications capitalize on the local field intensity, which in turn depends on the size of plasmonic nanocavities. Indeed, properly designed structures provide significant local field intensity and deep trapping potential, leading to manipulation of nano-objects with low laser power. The relationship between optical trappinginduced resonance shift and potential energy of plasmonic nanocavity can be analytically expressed in terms of the intercavity field intensity. Within this framework, recent experimental works on trapping and sensing of single nanoparticles and small molecules with plasmonic nanotweezers are discussed. Furthermore, significant consideration is given to conjugation of optical tweezers with Raman spectroscopy, with the aim of developing innovative biosensors. These devices, which take the advantages of plasmonic nanocavities, will be capable of trapping and detecting nanoparticles at the single molecule level.

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Section: Optical Properties Of Plasmonic Nanocavitiesmentioning

confidence: 99%

g = 2 r (\frac{1}{a} \sqrt{a^{2} - b^{2}} - 1)

Section: Optical Properties Of Plasmonic Nanocavitiesmentioning

confidence: 99%

See 1 more Smart Citation

Novel Plasmonic Nanocavities for Optical Trapping‐Assisted Biosensing Applications

Koya

Cunha

Guo

et al. 2020

Advanced Optical Materials

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“…However, the near field has intrinsic difficulties under conditions of low output power and a restricted operation range from the source. Combined with the surface plasmon effect, the light transmission can be highly enhanced by the ridge shape of the nanoaperture [3,4].…”

Section: Introductionmentioning

confidence: 99%

Relative positioning method for near-field beam spot array with optical microscope image of lithographic patterns using linear regression

Jang

Hahn

2017

Appl. Opt.

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A method for simply analyzing the relation between spot positions of near-field beam sources with micrometer pitch is proposed using an optical microscope. Based on the locations of spots in an optical microscopy image of lithographic patterns, the effective relative position is derived using simple linear regression. Numerical analysis is performed to introduce the concept and to evaluate the methodology with random noise. The accuracy and uncertainty of the proposed method are discussed. To confirm the method's feasibility, the experiments are conducted using fabricated probe array, and the experimental and numerical results are compared on the basis of uncertainty. An arbitrary pattern is recorded with respect to relative coordinates obtained based on the effective positions. We suggest a simple strategy for controlling beam spot array locations for pattern design in near-field lithography with less than 5-nm uncertainty.

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“…Thus, the far-field or propagating field can pass through the aperture17. For practical applications, many researchers have focused on the spectral resonance of the ridge aperture in terms of its geometrical dimensions1819. From another point of view, extending a ridge aperture, such as through three-dimensional surface patterning, requires an analytical description of the field distribution around it.…”

mentioning

confidence: 99%

Characterization of three-dimensional field distribution of bowtie aperture using quasi-spherical waves and surface plasmon polaritons

Park

Jung

Hahn

2017

Sci Rep

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We present an analytical formula to predict the three-dimensional field distribution of a nanoscale bowtie aperture using quasi-spherical waves (QSWs) and surface plasmon polaritons, which are excited by the fundamental waveguide mode and local plasmons of the aperture, respectively. Assuming two separate bowtie apertures in a metal film, we analysed the decay characteristics of QSWs using a finite difference time-domain method. To verify the formula, we recorded the spot patterns of the bowtie aperture on a photoresist film using various exposure times, and fit the patterns to the analytical formula in terms of the width and depth of the patterns. In addition, it was found that the formula successfully represented the dipole characteristics of the spot patterns, which were in agreement with the surface geometry, with a root-mean-square error of 9.4%. We expect that our theoretical formula will extend the potential applications of nanoscale bowtie apertures to plasmonic device fabrication, three-dimensional plasmonic lithography, and other technologies.

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Resonant Effects in Nanoscale Bowtie Apertures

Cited by 11 publications

References 25 publications

Novel Plasmonic Nanocavities for Optical Trapping‐Assisted Biosensing Applications

Novel Plasmonic Nanocavities for Optical Trapping‐Assisted Biosensing Applications

Relative positioning method for near-field beam spot array with optical microscope image of lithographic patterns using linear regression

Characterization of three-dimensional field distribution of bowtie aperture using quasi-spherical waves and surface plasmon polaritons

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