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Spectral properties of the hydroxy polycyclic aromatic hydrocarbons (2-naphthol, 1-hydroxypyrene and 1-hydroxyfluorene) were studied in solvents (methanol, ethanol, 1-propanol and 1-hexanol) room temperature emission and excitation spectroscopy. Different values of slit width have been used (1.5, 3, 5, 10 and 15 nm). The results show that the FWHM and the intensity of the fluorescence signal affect using different silt width; generally, higher slit width will exhibit larger intensity value with lower details of fluorescence signal. With using different solvent, the results show wide range of differences between different solvents and these effects due to the different solvation process. [ABSTRACT FROM AUTHOR]

Excitation of novel graphene plasmons is examined using finite-element analysis via COMSOL RF module 5.6. The theoretical model is simulated with graphene grating on the glass substrate having fixed periodicity (Λ = 700 nm) by illumination with transverse magnetic (TM) polarized light through the substrate side. The effect of thickness variation on SPPs excitation has been acquired from transmission spectra while keeping the periodicity and slit width of grating structure constant via analyzing the trend followed by the resonance dips. The electric and magnetic field behavior has also been analyzed for each thickness, and a specific grating thickness of 10 nm was taken into consideration owing to the thickness constraints regarding graphene. Slit width variation of the grating structure has been investigated using far-field analysis to observe the formation of SPPs from transmission spectra and near-field analysis for understanding the underlying physics. These analyses resulted in SPP excitation more appreciable at slit widths in between 250 and 350 nm. The slit width range regarding the chosen periodicity supports the most efficient plasmonics mode and many applications of such devices are found in real life. [ABSTRACT FROM AUTHOR]

This paper reports the behavior of extraordinary optical transmission (EOT) through 1D plasmonic nanostructure devices when thickness and periodicity of silver film simulated on glass substrate are fixed and only slit width is varied. Transverse magnetic (TM) polarized photon incident normally at the grating structure and zero-order transmission spectra has been extracted. Fano-resonance associate with the excitation of the surface plasmon polaritons (SPPs) has been evaluated carefully to calculate EOT. Excited plasmons along with the Febry-Perot mode have contributed toward the EOT through the periodic slits in the grating device. It has been found that its numerical value of EOT is maximum at a particular slit width, i.e., 409 nm, which is greater than one half and less than two third of periodicity, when wavelength of light is comparable with periodicity. This unique behavior is associated with the maximum incident energy coupled to the excited plasmon due to fundamental plasmonic mode being the most efficient. Such optimal devices find many applications in real world, e.g., light-emitting diodes (LEDs), biosensing, and SERs. [ABSTRACT FROM AUTHOR]

The present work investigates the effect of geometrical parameters of 1D nanograting on surface plasmon resonance (SPR) and plasmonic bandgap (PBG). The use of plasmonic grating device in various electronic devices is based on correct value of bandgap energy. For this purpose, various nanograting structures having regular periodic ridges in 1D has been modeled in the form of a gold film on glass substrate using finite element analysis in RFRF Module of COMSOL (Multiphysics) 5.3a licensed version. In the designed structures, firstly, the periodicity of the grating varied while keeping the slit width and film thickness constant. Furthermore, the thickness of the grating also varied while the periodicity and slit width is kept constant and transmitted mode for each structure is studied to find the suitable value of film thickness for optimizing the device. At the end, the slit width varied while keeping the periodicity and film thickness constant. Due to increase in slit width, the bandgap energy increases until slit width equals to nearly half of periodicity after this bandgap energy decreases and associated with the sinusoidal behavior of the device which support fundamental plasmonic mode. The increase in film thickness results a linear increase in bandgap energy as long as the film thickness is comparable to the skin depth of gold and plasmonic bandgap energy is high for smaller values of periodicity and decreases with increasing periodicity. Due to the ability to control the optical properties, the PBG is expected to have a major impact on technology. [ABSTRACT FROM AUTHOR]

Effect of different gold (Au) grating structures on light absorption in solar cell is investigated by finite elemental analysis using COMSOL multiphysics-RF module. The geometry of the solar cell consists of a 50-nm Au film on the substrate of amorphous silicon (a-Si). An optimum value of the slit width (w) of the Au grating has been obtained whereas periodicity of the grating structure remained the same. The periodicity in the grating device was chosen in such a way that the excitation of the surface plasmon polritons (SPPs) lies in the IR or NIR region where most of the spectrometers work well in practical life. Far-field transmission spectra were extracted from the grating device when illuminating with p-polarized light through the substrate side. Near-field plots of the Fano resonance (dip) associated with the excitation of the surface plasmon polritons (SPPs) were carefully examined to understand the underlying physics. It was deduced from the results that a grating device with slit width of 250-350 nm is the most efficient which reveals the fact that such device offers intermediate scattering from the grating structure and supports fundamental plasmonic mode. Hence, such devices absorb more light being most efficiently and find application in solar cell. [ABSTRACT FROM AUTHOR]

This research work reports the excitation of surface plasmon polaritons (SPPs) in a 1D grating device in a gold film on glass substrate. Various grating structures have been modelled using finite element analysis (FEA) in comsol RF module. The periodicity in such devices remains constant, whereas slit width is changed for each structure. We have studied the effects of slit width on SPP resonances and formation of the plasmonic bandgap. The trend shows that bandgap energy increases with increasing slit width and reaches a maximum value for slit width nearly equal to half of the periodicity in the grating structure and then decreases which is a new and important observation. The possible reason for this optimum value of the slit width corresponds to the absence of higher plasmonic modes and the sinusoidal nature of the slit. [ABSTRACT FROM AUTHOR]