Zinc oxide nanostructures for fluorescence and Raman signal enhancement: a review

• Ioana Marica,
• Fran Nekvapil,
• Maria Ștefan,
• Cosmin Farcău and
• Alexandra Falamaș

Beilstein J. Nanotechnol. 2022, 13, 472–490, doi:10.3762/bjnano.13.40

• intensity of the evanescent field. These properties explain the second mechanism of fluorescence enhancement of ZnO NRs. Regardless of the origin of fluorescence enhancement, ZnO nanosubstrates proved to be economical and sensitive arrays that could be mass-produced for broad applications in clinic

Optically and electrically driven nanoantennas

• Monika Fleischer,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2020, 11, 1542–1545, doi:10.3762/bjnano.11.136

• spectroscopy (SERS); tip-enhanced Raman spectroscopy (TERS); tunnel junction; Editorial Optical antennas + serve to confine the energy of photons transported by a light wave to a tiny volume much smaller than the wavelength; or reversely, to convert the energy of an evanescent field that oscillates at optical

Liquid crystal tunable claddings for polymer integrated optical waveguides

• José M. Otón,
• Manuel Caño-García,
• Fernando Gordo,
• Eva Otón,
• Morten A. Geday and
• Xabier Quintana

Beilstein J. Nanotechnol. 2019, 10, 2163–2170, doi:10.3762/bjnano.10.209

• power transfer with a characteristic coupling distance called “beat length”, Lbeat. The beat length depends on the difference between effective refractive indices of the odd and the even optical modes of the coupler [9]: and, thus, on the magnitude of the evanescent field and the distance between the

• guides. Practical uses of integrated directional couplers require the beat length to be in the micrometer range. This range is found either when the fraction of evanescent field is significant or when the distance between the guides is very low. The first option requires that core and cladding indices

• the cladding index, as in the polymer guides with LC cladding studied here. The effect of cladding on the MMI field profile is boosted by the increment of the evanescent field, which is achieved by reducing the physical dimensions of the waveguide, and the difference between the core and cladding

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

• in a plane at a distance, d, from the sample if this part is not parallel to the measurement plane. The measurement of the out-of-plane stray field part, Bz (x, y; z = d + h), can be easily reconstructed under the assumption of the evanescent-field analog of Huygens’ principle from the measured B

Experimental study of an evanescent-field biosensor based on 1D photonic bandgap structures

• Jad Sabek,
• Francisco Javier Díaz-Fernández,
• Luis Torrijos-Morán,
• Zeneida Díaz-Betancor,
• Ángel Maquieira,
• María-José Bañuls,
• Elena Pinilla-Cienfuegos and
• Jaime García-Rupérez

Beilstein J. Nanotechnol. 2019, 10, 967–974, doi:10.3762/bjnano.10.97

• of proteins. As the sensing in this type of structures is governed by the interaction between the evanescent field going into the cladding and the target analytes, scanning near-field optical microscopy has been used to characterize the profile of that evanescent field. The study confirms the strong

• to bovine serum albumin (BSA) using a UV-induced immobilization procedure. The use of half-antibodies allows one to reduce the thickness of the biorecognition volume down to ca. 2.5 nm, thus leading to a higher interaction with the evanescent field, as well as a proper orientation of their binding

• sites towards the target sample. Then, the biofunctionalized PBG biosensor has been used to perform a direct and real-time detection of the target BSA antigen. Keywords: evanescent field; half-antibodies; light-assisted immobilization; photonic bandgap sensor; SNOM characterization; Introduction The

Commercial polycarbonate track-etched membranes as substrates for low-cost optical sensors

• Paula Martínez-Pérez and
• Jaime García-Rupérez

Beilstein J. Nanotechnol. 2019, 10, 677–683, doi:10.3762/bjnano.10.67

• an evanescent field with the target substance are the best known [2]. However, this kind of optical sensor presents a limited sensitivity, as only part of the light interacts with the substances of interest. To overcome this limitation, porous materials are a good option. Since they allow the

Magnetic-field sensor with self-reference characteristic based on a magnetic fluid and independent plasmonic dual resonances

• Kun Ren,
• Xiaobin Ren,
• Yumeng He and
• Qun Han

Beilstein J. Nanotechnol. 2019, 10, 247–255, doi:10.3762/bjnano.10.23

• theoretical analysis. When a disk is coupled to the upper stub 1, cavities modes can directly couple with each other through their evanescent field at small gap distances. When ω1 = ωd = ω, the transmittance of Equation 8 becomes T = |(κ1d + 1)/(κw1 + κ1d + 1)|2. This indicates that a transmission peak

Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

• Pavel Loiko,
• Tanujjal Bora,
• Josep Maria Serres,
• Haohai Yu,
• Magdalena Aguiló,
• Francesc Díaz,
• Uwe Griebner,
• Valentin Petrov,
• Xavier Mateos and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2018, 9, 2730–2740, doi:10.3762/bjnano.9.255

• defects in the ZnO structure. Second, the ZnO NRs can be hydrothermally grown directly on the crystal surface. This technology is especially attractive for the PQS waveguide lasers relying on the evanescent field interaction with the SA deposited on top of the active layer/channel. Taking into account the

Dumbbell gold nanoparticle dimer antennas with advanced optical properties

• Janning F. Herrmann and
• Christiane Höppener

Beilstein J. Nanotechnol. 2018, 9, 2188–2197, doi:10.3762/bjnano.9.205

• corresponding diameter of the foremost AuNP, the optical response of the excited molecule corresponds to the pure confocal excitation, i.e., the evanescent field of the antenna is entirely faded out and quenching by the metallic interface of the antenna is negligible. For smaller distances at first the

Surface characterization of nanoparticles using near-field light scattering

• Eunsoo Yoo,
• Yizhong Liu,
• Chukwuazam A. Nwasike,
• Sebastian R. Freeman,
• Brian C. DiPaolo,
• Bernardo Cordovez and
• Amber L. Doiron

Beilstein J. Nanotechnol. 2018, 9, 1228–1238, doi:10.3762/bjnano.9.114

• (trapping force), scattering force, coating force, and drag force (Figure 1) [21]. Nanoparticles are either trapped in the evanescent field and reside in a potential well or escape the potential well via Brownian motion due to inadequate trapping force [22]. The potential well is the sum of all forces, and

• the local intensity of the laser light at the location the nanoparticle. Assuming the evanescent field behaves as I = Imax exp(−βz), we obtain the following expression for z after expanding about an average height above the waveguide, zave: where αave is the average polarizability of a particle. The

• in the evanescent field. If we expect variations in z to be ±10 nm, then with I = Imax exp(−βz), the variation in scattered light due to position is ≈10%, which is ≈100× less than observed in the experiment. In previous studies (Hristov et al., 2017), the particle material was held constant while

Refractive index sensing and surface-enhanced Raman spectroscopy using silver–gold layered bimetallic plasmonic crystals

• Somi Kang,
• Sean E. Lehman,
• Matthew V. Schulmerich,
• An-Phong Le,
• Tae-woo Lee,
• Stephen K. Gray,
• Rohit Bhargava and
• Ralph G. Nuzzo

Beilstein J. Nanotechnol. 2017, 8, 2492–2503, doi:10.3762/bjnano.8.249

• the most commonly used plasmonic materials because they generate strong plasmonic resonances at visible and near-infrared frequencies [39]. Metallic Ag generates a stronger evanescent field and a narrower plasmon resonance than Au, which in principle is advantageous for both optical sensing and SERS

Surface-enhanced infrared absorption studies towards a new optical biosensor

• Lothar Leidner,
• Julia Stäb,
• Jennifer T. Adam and
• Günter Gauglitz

Beilstein J. Nanotechnol. 2016, 7, 1736–1742, doi:10.3762/bjnano.7.166

• ”), larger sensing volume (for evanescent field sensors due to the enhanced penetration depth), and the possibility to extract additional information by chemometric methods. An additional advantage is the increasing manufacturing tolerance compared to the visible region. This leads to the proposal to combine

• evanescent field of a guided wave (as is the above-mentioned MZI sensor), will show only a moderate absorption spectra, as the sensing volume is limited by the penetration depth of the evanescent field. This fact is both an advantage and a disadvantage. Biosensors often operate in aqueous solution, which

• aqueous solution by a RIfS set-up operating in the mid-infrared. Unlike ATR, where the monitored absorption occurs within the evanescent field of a guided, totally reflected wave mode, the RIfS signal is governed by the effects of reflection, transmission and absorption including interference caused by

Highly compact refractive index sensor based on stripe waveguides for lab-on-a-chip sensing applications

• Chamanei Perera,
• Kristy Vernon,
• Elliot Cheng,
• Juna Sathian,
• Esa Jaatinen and
• Timothy Davis

Beilstein J. Nanotechnol. 2016, 7, 751–757, doi:10.3762/bjnano.7.66

• the input arm can be excited via end-fire excitation or grating coupling. This mode propagates along the input arm until its evanescent field starts to interact with the two outer arms. Li is the length of the input waveguide before coupling with the outer arms, Lc is the coupling length and Ls is the

Orthogonal chemical functionalization of patterned gold on silica surfaces

• Francisco Palazon,
• Didier Léonard,
• Thierry Le Mogne,
• Francesca Zuttion,
• Céline Chevalier,
• Magali Phaner-Goutorbe,
• Éliane Souteyrand,
• Yann Chevolot and
• Jean-Pierre Cloarec

Beilstein J. Nanotechnol. 2015, 6, 2272–2277, doi:10.3762/bjnano.6.233

• ] or other [27][28] self-assembled monolayers may provide a higher diversity of potential biomolecules to immobilize. Shorter spacer chains (e.g., short alkyl chains) may also be useful to immobilize the target as close to the metal surface (i.e., the maximum intensity of the evanescent field) as

Localized surface plasmon resonances in nanostructures to enhance nonlinear vibrational spectroscopies: towards an astonishing molecular sensitivity

• Dan Lis and
• Francesca Cecchet

Beilstein J. Nanotechnol. 2014, 5, 2275–2292, doi:10.3762/bjnano.5.237

• authors used a SPP wave to locally generate a SE-CARS emission from NPs adsorbed on the gold surface. By comparison to the non-propagative wave configuration relying solely on an evanescent field, an amplification of two orders of magnitude was obtained. Finally, the authors collected the nonlinear

Distance dependence of near-field fluorescence enhancement and quenching of single quantum dots

• Volker Walhorn,
• Jan Paskarbeit,
• Heinrich Gotthard Frey,
• Alexander Harder and
• Dario Anselmetti

Beilstein J. Nanotechnol. 2011, 2, 645–652, doi:10.3762/bjnano.2.68

• evanescent field and the AFM cantilever tip (Figure 3a). At small tip distances a strong field enhancement is observed that rapidly decreases with growing gap size. This strong distance dependence is characteristic of dipole–dipole coupling effects. Upon further retraction from the surface Γexc exhibits a

Towards multiple readout application of plasmonic arrays

• Dana Cialla,
• Karina Weber,
• René Böhme,
• Uwe Hübner,
• Henrik Schneidewind,
• Matthias Zeisberger,
• Roland Mattheis,
• Robert Möller and
• Jürgen Popp

Beilstein J. Nanotechnol. 2011, 2, 501–508, doi:10.3762/bjnano.2.54

• evanescent decay on the metal surface. This strong field enhancement by the evanescent field can be employed for an effective enhancement of the weak Raman cross section (surface-enhanced Raman spectroscopy – SERS) [25] and also of the fluorescence signal (surface-enhanced fluorescence – SEF) [26]. However