A ray-theoretic analysis of the problem of discontinuity in a linear guide is presented. The fields in the guides are expressed as superposition of plane wave components determined by subjecting the fields to the process of Fourier transformation. The reflected fields are finally synthesized by modifying these plane wave components by the corresponding Fresnel coefficients at the plane of discontinuity. The results obtained are compared with those obtained by other methods.
Modeling of a fused silica (SiO2) glass prism-based plasmonic structure comprising of indium oxide (In2O3)–zirconium dioxide (ZrO2)–silver (Ag)–zinc oxide (ZnO) intermediate layers showing enhancement in sensitivity and figure-of-merit (FOM) in visible and infrared regime has been reported in this paper. Performance of the proposed plasmonic structure has been demonstrated in terms of sensitivity, half width (HW), detection accuracy (DA), and FOM parameters in visible (632.8 nm) and infrared (1200 nm) wavelength of light. High sensitivity of fused silica glass material, In2O3, ZnO films along with high DA and high FOM of Ag and inclusion of ZrO2 as an oxidation protective layer in between In2O3 and Ag have been the most exciting and advantageous features of our proposed structure. Simulated sensitivity values of our proposed structure were found to be 73.8 deg/RIU at 632.8 nm wavelength and it was found enhanced to 109.6 deg/RIU at 1200 nm wavelength and simulated FOM values were also found enhanced from 23.3544 RIU−1 at 632.8 nm to 62.6285 RIU−1 at 1200 nm wavelength for change in sensing layer refractive indices from 1.30 RIU to 1.35 RIU.
We report a transmission line based analysis of a subwavelength nanostub coupled to a metal-dielectric-metal (MDM)
waveguide along with a differential intensity based sensing application related to detection of concentration of glucose in
aqueous solution.
This paper aims to report simulation based study of performance properties of Titanium Nitrides and their efficient use
as substitutes to metals for excitation and propagation of surface plasmon polariton wave.
Moiré pattern, produced by the overlapping of two radially sheared beams emerging from two longitudinally shifted
focal points of a birefringent lens has been experimentally demonstrated. Coherent and incoherent Moiré patterns are
generated with and without analyzer. Birefringent samples like mica sheets with opposite crystal axis to that of the
birefringent lens modulate the Moiré pattern. Mica sheet of different thicknesses have been used to demonstrate the
effect of thickness on phase retardation, hence on fringe pattern. Experimentally birefringence has been calculated by
fringe analysis and compared with theoretically simulated birefringence.
Theoretical and experimental investigation of surface plasmon resonance (SPR) assisted radially sheared interference
imaging using a birefringent lens having two longitudinally shifted focal points has been reported. As Wolllaston prism
can introduce lateral shear between the two mutual orthogonal polarizations of radially sheared pattern, Moiré-like
pattern is produced at overlapping region of those patterns. Brief theory and experimental demonstration of coherent and
incoherent Moiré fringe generation has been done. Surface plasmon resonance (SPR) mediated Moiré pattern has been
demonstrated which can be further utilized for other nanophotonic applications.
In present analysis a semiconductor-based surface plasmon resonance structure using Gr-IV materials (Silicon and
Germanium) has been analyzed in spectral interrogation mode which can be used for efficient environmental monitoring
and Infrared (IR) gas-sensing purposes. The Silicon-Germanium (Si-Ge) combination structure is able to confine an
extremely high evanescent field in the sensing region due to their extraordinary high refractive indices (RI). Higher
concentration of optical field in the sensing area provides enhanced spectral sensitivity for infrared gas-sensing. Better
detection accuracy and adequate dynamic range are other additional advantages offered by such semiconductor-based
surface plasmon resonance (SPR) configurations. Analysis of the SPR structure has also been carried out in terms of
detection accuracy, figure of merit and Q-factor of the gas-sensor.
In this work, admittance loci method is used to model and analyze performance of a chalcogenide prism based plasmonic
biosensor comprising of gold metal nanoparticle film for detection of wavelength dependent refractive index change of
human blood sample under angular interrogation mode. The wavelength dependent performance of the plasmonic
biosensor based on the choice of chalcogenide (2S2G) as a coupling prism material has been discussed with the help of
performance parameter plots.
A prism coupler-based nano-plasmonic sensor consisting of a high refractive index (RI) prism (2S2G-prism, LASF9-prism), gold (Au) metal film, and different amino acids as the dielectric sample is used for sensing in attenuated total internal reflection mode. An additional semiconductor (silicon) nano-layer over the gold surface has been used for increasing the stability and sensitivity of the surface plasmon resonance sensor. A comparative analysis of performance of the nano-plasmonic sensors in the spectral regime using these two high RI prism materials with an additional semiconductor nano-layer has been presented. The sensing performance of the proposed nano-plasmonic sensors in terms of evanescent field enhancement, spectral sensitivity, detection accuracy, figure of merit, and Q-factor with different amino acid samples has been discussed along with supporting theoretical simulations in a MATLAB® environment.
A Kretschmann-Raether prism-based three-layer structure consisting of a prism, gold (Au) metal film, and dielectric sample has been investigated with the use of admittance loci method in attenuated total internal reflection mode. High index prism materials like silicon, chalcogenide (2S2G), and SF14 have been used to study their effect on surface plasmon resonance (SPR) sensing (at 1200-nm wavelength) in infrared region by corresponding admittance loci plots and also by SPR sensing curves. The performance of the sensor based on the choice of the prism material has been discussed with the help of sensitivity plots giving due importance to the dynamic range of the designed sensor.
We theoretically analyze waveguide coupled surface plasmon resonance structure to investigate the coupling phenomenon between waveguide resonance and plasmonic resonance. Variations of types of metals as well as changes of thickness of the waveguide layer produce some interesting phenomena in the context of coupled plasmonics. Different modes that are generated are found to have dual contributions of waveguide and plasmonic effects. Field enhancement and reflectance contour plots with simultaneous angular and wavelength interrogation give some insight into the effect of waveguide resonance on the performance of nanoplasmonic structure. Figure of merit calculations and comparison of angular and wavelength differential curves of different nanoplasmonic structures can be used to determine the right candidature as regarding the better sensing performance compared to conventional SPR based sensor. Moreover, the important role played by the thickness of the waveguide layer is also established with supporting simulations.
In this paper, we report the theoretical analysis of different types of plasmonic structures with the main emphasis on the coupled plasmon waveguide resonance due to several advantages offered by the same compared to other structures. Multiple resonance dips are found to increase with the increase in the dielectric layer thickness and this progressive nature of the dips can be efficiently utilized to characterize the dielectric material within a composite multilayer plasmonic structure. Supporting simulation results carried out in the MATLAB environment are also provided to validate the proposed application.
A confocal microscopic setup with a pair of birefringent lenses having their crystal axes crossed is used to measure birefringence of thin samples. The method can be used to measure phase down to the order of /10. The fast and slow axes of the object also can be identified. The principle of the method along with the experimental setup is described. Some first-order experimental results are also presented.
The design and fabrication of a fiber optic pH sensor working on the basis of evanescent wave absorption is presented. A pH sensitive dye is immobilized on the uncladded portion of the optic fiber by sol-gel route. The sensitivity of the device is found to increase when multiple sol-gel coatings are used as the cladding in the sensing region. The sensor response and its dynamic range are reported for two pH indicator dyes, vis. bromocresol purple and bromocresol green.
A method for measurement of refractive index profile of a GRIN system is developed based on a longitudinal interferometer using a birefringent lens. The fringe pattern so generated is made to traverse through the sample under test. The modification of the fringes gives a measure of the refractive index profile. The fringe patterns both in presence and absence of the test samples are grabbed by a CCD camera and further processed by a computer. The basic software required for the same is being developed. Some experimental results are presented.
In the present report several implementation of trinary logic functions using three logical values 1 0 and 1 will be presented. Fredkin gate having three input and three output lines has been suggested as a basic building block of an optical computer. In this paper a binary coded trinary (BCT) method has been used to represent each trinary number and several similar logic functions in blocks using Fredkin gates are proposed. I.
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