Study of TiN nanodisks with regard to application for Heat-Assisted Magnetic Recording

MRS Advances ◽  
2016 ◽  
Vol 1 (5) ◽  
pp. 317-326 ◽  
Author(s):  
Jacek Gosciniak ◽  
John Justice ◽  
Umar Khan ◽  
Brian Corbett
Keyword(s):  
Titanium Nitride ◽  
Data Storage ◽  
Near Field ◽  
Polarized Light ◽  
Higher Order ◽  
Plasmonic Material ◽  
Order Resonance ◽  
Resonance Modes ◽  
Higher Order Modes ◽  
Transmission Measurements

ABSTRACTIn recent years titanium nitride is being considered as a very promising plasmonic material for data storage applications as it exhibits a pronounced plasmonic dipolar resonance and has high thermal stability. However, there is a lack of research where higher order resonance modes are examined. We address this here by performing angle dependent spectral transmission measurements nanodisks arrays made from titanium nitride. The measurements show strong polarization dependence with s-polarized light causing excitation of the quadrupole and higher order resonance plasmonic modes. These higher order modes are required for the state-of-the-art designs of near-field transducers. This, together with its outstanding thermal properties, makes TiN a favourable material for data storage applications.

scholarly journals Dye-doped spheres with plasmonic semi-shells: Lasing modes and scattering at realistic gain levels

2013 ◽  
Vol 4 ◽  
pp. 974-987 ◽  
Author(s):  
Nikita Arnold ◽  
Boyang Ding ◽  
Calin Hrelescu ◽  
Thomas A Klar
Keyword(s):  
Cross Section ◽  
Near Field ◽  
Field Enhancement ◽  
Higher Order ◽  
Silver Layer ◽  
Far Field ◽  
Spectral Features ◽  
Polystyrene Spheres ◽  
Higher Order Modes ◽  
Lasing Modes

We numerically simulate the compensation of absorption, the near-field enhancement as well as the differential far-field scattering cross section for dye-doped polystyrene spheres (radius 195 nm), which are half-covered by a silver layer of 10–40 nm thickness. Such silver capped spheres are interesting candidates for nanoplasmonic lasers, so-called spasers. We find that spasing requires gain levels less than 3.7 times higher than those in commercially available dye-doped spheres. However, commercially available concentrations are already apt to achieve negative absorption, and to narrow and enhance scattering by higher order modes. Narrowing of the plasmonic modes by gain also makes visible higher order modes, which are normally obscured by the broad spectral features of the lower order modes. We further show that the angular distribution of the far-field scattering of the spasing modes is by no means dipole-like and is very sensitive to the geometry of the structure.

scholarly journals k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy

2013 ◽  
Vol 4 ◽  
pp. 603-610 ◽  
Author(s):  
Martin Esmann ◽  
Simon F Becker ◽  
Bernard B da Cunha ◽  
Jens H Brauer ◽  
Ralf Vogelgesang ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Optical Microscopy ◽  
Frequency Domain ◽  
Near Field ◽  
Higher Order ◽  
Far Field ◽  
Radiation Patterns ◽  
Background Ratio ◽  
Higher Order Modes ◽  
Spatial Frequency Domain

We investigate the radiation patterns of sharp conical gold tapers, which were designed as adiabatic nanofocusing probes for scanning near-field optical microscopy (SNOM). Field calculations show that only the lowest order eigenmode of such a taper can reach the very apex and thus induce the generation of strongly enhanced near-field signals. Higher-order modes are coupled into the far field at finite distances from the apex. Here, we demonstrate experimentally how to distinguish and separate between the lowest and higher-order eigenmodes of such a metallic taper by filtering in the spatial frequency domain. Our approach has the potential to considerably improve the signal-to-background ratio in spectroscopic experiments at the nanoscale.

scholarly journals Terahertz Sensing for R/S Chiral Ibuprofen via All-Dielectric Metasurface with Higher-Order Resonance

2021 ◽  
Vol 11 (19) ◽  
pp. 8892
Author(s):  
Weinan Shi ◽  
Fei Fan ◽  
Ziyang Zhang ◽  
Tianrui Zhang ◽  
Shanshan Li ◽  
...  
Keyword(s):  
Trace Amount ◽  
Expansion Method ◽  
Multipole Expansion ◽  
Higher Order ◽  
Chiral Molecules ◽  
Order Resonance ◽  
Resonance Modes ◽  
Enhanced Sensitivity ◽  
Multipole Expansion Method ◽  
Dielectric Metasurface

A terahertz (THz) all-dielectric metasurface with crescent cylinder arrays for chiral drug sensing has been demonstrated. Through the multipole expansion method, we theoretically found that breaking the symmetry of the metasurface can excite higher-order resonance modes and provide stronger anisotropy as well as enhanced sensitivity for the surroundings, which gives a better sensing performance than lower-order resonance. Based on the frequency shift and transmittance at higher-order resonance, we carried out the sensing experiments on (R)-(−)-ibuprofen and (S)-(+)-ibuprofen solution on the surface of this metasurface sensor. We were able to monitor the concentrations of ibuprofen solutions, and the maximum sensitivity reached 60.42 GHz/mg. Furthermore, we successfully distinguished different chiral molecules such as (R)-(−)-ibuprofen and (S)-(+)-ibuprofen in the 5 μL trace amount of samples. The maximum differentiation was 18.75 GHz/mg. Our analysis confirms the applicability of this crescent all-dielectric metasurface to enhanced sensing and detection of chiral molecules, which provides new paths for the identification of biomolecules in a trace amount.

Numerical study of anomalous TE-polarized light scattering by metallic nanowires using realistic data

2014 ◽  
Vol 23 (01) ◽  
pp. 1450005 ◽  
Author(s):  
G. Wesley Putra Data ◽  
Alexander A. Iskandar ◽  
May-On Tjia
Keyword(s):  
Light Scattering ◽  
Numerical Study ◽  
Polarized Light ◽  
Spectral Width ◽  
Higher Order ◽  
Gold Nanowires ◽  
Higher Order Modes ◽  
Resonance Curves ◽  
Refractive Index Data ◽  
Realistic Data

We report the result of a numerical study of surface plasmon induced anomalous behaviors in TE light scattering by single silver and gold nanowires of radius a. Going beyond the restricted case of nondissipative and nondispersive scatterers often reported previously, the current numerical calculation is performed directly on the basis of Mie's general formula, adopting the refractive index data of Johnson and Christy. Our result does not show the appearance of well resolved and multipole resonances in Q sca plotted against q(= 2πa/λ), for certain wire radii. It does show however, the growing contributions of the higher order modes as a increases. A series of closely-placed but well separated resonance curves nevertheless show up for varying wire radii within the range of small q, exhibiting systematic changes indicative of the size effects on the scattered waves. The further deduced Q sca (λ) spectra display the distinct resonance curves for different wire radii showing peculiar mix of monotonous and nonmonotonous variations of the resonance peak and spectral width with increasing a, as a result of complicated competitions among the growing contributions of the higher order modes. Finally, while the silver and gold scatterers appear to exhibit qualitatively similar behaviors, they differ largely in details due to the significantly different indices of refraction and dispersive properties.

scholarly journals Numerical Investigation of the System-Matrix Method for Higher-Order Probe Correction in Spherical Near-Field Antenna Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Thorkild B. Hansen
Keyword(s):  
Condition Number ◽  
Matrix Method ◽  
Near Field ◽  
Higher Order ◽  
Normal Matrix ◽  
Identity Matrix ◽  
System Matrix ◽  
Higher Order Modes ◽  
Near Field Scanning ◽  
Least Squares Approach

The system-matrix method for higher-order probe correction in spherical near-field scanning is based on a renormalized least-squares approach in which the normal matrix closely resembles the identity matrix when most of the energy of the probe pattern resides in the first-order modes. This method will be “stressed-tested” in the present paper by employing probes for which up to 49% of the pattern energy resides in the higher-order modes. The condition number of the resulting normal matrix will be computed, and its “distance” from the identity matrix displayed. It is also shown how the condition number of the normal matrix can be further reduced.

Strong near-field couplings of anapole modes and the formation of higher-order electromagnetic modes in stacked all-dielectric nanodisks

2021 ◽  
Author(s):  
Bin Liu ◽  
Ma-Long Hu ◽  
Yi-Wen Zhang ◽  
Yue You ◽  
Zhao-Guo Liang ◽  
...  
Keyword(s):  
Electric Dipole ◽  
Near Field ◽  
Higher Order ◽  
Dipole Mode ◽  
Order Mode ◽  
Quadrupole Mode ◽  
Higher Order Modes ◽  
Scattering Spectrum ◽  
Magnetic Dipole Resonances ◽  
Higher Order Mode

Abstract We theoretically study the near-field couplings of two stacked all-dielectric nanodisks, where each disk has an electric anapole mode consisting of an electric dipole mode and an electric toroidal dipole (ETD) mode. Strong bonding and anti-bonding hybridizations of the ETD modes of the two disks can occur. The bonding-hybridized ETD can interfere with the dimer's electric dipole mode and induce a new electric anapole mode. The anti-bonding hybridization of the ETD modes can induce a magnetic toroidal dipole (MTD) response in the disk dimer. The MTD and magnetic dipole resonances of the dimer form a magnetic anapole mode. Thus, two dips associated with the hybridized modes appear on the scattering spectrum of the dimer. Furthermore, the MTD mode is also accompanied by an electric toroidal quadrupole mode. The hybridizations of the ETD and the induced higher-order modes can be adjusted by varying the geometries of the disks. The strong anapole mode couplings and the corresponding rich higher-order mode responses in simple all-dielectric nanostructures can provide new opportunities for nanoscale optical manipulations.

Sign in / Sign up

Export Citation Format

Share Document