P-polarized Light Research Articles

Controlling Electrical Conduction through Noble Metal Thin Films by Surface Plasmon Resonance

We have conducted in situ measurements of the surface plasmons and electrical resistivity of noble metal thin films. We present results for the electrical resistivity of these materials as functions of the angle of incidence for p-polarized light of wavelength λ = 632 nm in the Kretschmann configuration optical system. We observe a significantly lower resistivity (higher conductivity) under resonance conditions for the surface plasmon polaritons. The resistivity data are supported by COMSOL simulations of the evanescent fields associated with the surface plasmons. We discuss the resistivity data in terms of the theoretical models, which suggest that the electrical conductivity of the transition metals is sensitive to Umklapp electron-electron scattering and attractive interactions between free electrons because of the screening of the d-band electrons by the s-band electrons.

On the Application of Stacked Periodic Tungsten Grating Nanostructure in Wide-Range Plasmonic Sensing and Other Photonic Devices

At present, the nanostructures consisting of tungsten metal are hardly explored for surface plasmon resonance–based applications in sensing and other photonic devices. In this view, a plasmonic nanostructure consisting of stacked tungsten gratings on aluminum nitride substrate with nickel interlayer is proposed and simulated for refractive index (RI) sensing in the visible and near infrared spectral regions. Rigorous coupled wave analysis (RCWA) with p-polarized light source is used for simulation and analysis. The sodium chloride (NaCl) concentration in water and gaseous medium is considered analyte. The performance of proposed plasmonic sensor is demonstrated in terms of sensitivity, resolution, and figure-of-merit values. In addition, a detailed analysis is also performed to study the effect of grating variable values on the sensor’s performance. The angle of light incidence emerges as an important parameter in significantly enhancing the sensor’s performance as well as in tuning the sensor’s applicability as per available light source. Further, it is shown that the same probe can be applied as a gas sensor with high sensitivity and accuracy. Moreover, the prominent absorbance characteristics of the proposed nanostructure leads to possible applications in spectral filtering as well as photodetection in both visible and NIR spectral regions. Owing to the advanced properties of tungsten, the proposed structure will be beneficial for bio- and gas-sensing applications along with other photonic devices operable in a wide spectral range.

Electrons Generate Self-Complementary Broadband Vortex Light Beams Using Chiral Photon Sieves.

Planar electron-driven photon sources have been recently proposed as miniaturized light sources, with prospects for ultrafast conjugate electron-photon microscopy and spectral interferometry. Such sources usually follow the symmetry of the electron-induced polarization: transition-radiation-based sources, for example, only generate p-polarized light. Here we demonstrate that the polarization, the bandwidth, and the directionality of photons can be tailored by utilizing photon-sieve-based structures. We design, fabricate, and characterize self-complementary chiral structures made of holes in an Au film and generate light vortex beams with specified angular momentum orders. The incoming electron interacting with the structure generates chiral surface plasmon polaritons on the structured Au surface that scatter into the far field. The outcoupled radiation interferes with transition radiation creating TE- and TM-polarized Laguerre-Gauss light beams with a chiral intensity distribution. The generated vortex light and its unique spatiotemporal features can form the basis for the generation of structured-light electron-driven photon sources.

Oblique incidence infrared reflectance spectroscopy of phonons in cubic MgO, MnO, and NiO

The infrared (IR) reflectivity of the cubic metal oxides MgO, MnO, and NiO has been measured at room temperature using the technique of oblique incidence. The use of this technique at three angles of incidence provides multiple sets of spectra (including both s- and p-polarizations) to analyze when compared to the standard normal incidence case, which has been used extensively in the past for these compounds. It is shown that the transverse optic (TO) and longitudinal optic (LO) mode phonon parameters can be determined with greater accuracy by using the factorized model for the fits, as compared with the popular classical model used previously, and by fitting the derivative of the reflectivity. Our results for the phonon mode parameters are similar to those found earlier, as could be expected, but are generally more precise. An analysis of the difference in frequency of the TO mode in antiferromagnetic NiO at room temperature for the two polarizations of reflected light revealed a TO mode splitting of about 4 cm−1, with the p-polarized light TO mode having the higher frequency: This small splitting is in agreement with theoretical predictions. This more precise IR method for revealing the phonon mode behavior in such magnetically ordered cubic metal oxides, which are prototypes of strongly correlated electronic systems and have been found to be Mott-Hubbard insulators, may be readily applied to any similar antiferromagnetic system.

Detection of Leptospirosis Bacteria in Rodent Urine by Surface Plasmon Resonance Sensor Using Graphene

In this paper, a graphene-coated surface plasmon resonance sensor is designed for the examination of Rodent urine which is responsible for Leptospirosis bacteria. Rodent urine is considered as sensing medium. Graphene surface is activated by phosphate-buffered saline solution for better attachment of Leptospirosis bacteria on its surface. Oliguria and Polyuria are the Rodent urine with high and low concentrations of Leptospirosis bacteria, respectively. The transfer matrix method is used for the formulation of reflection intensity of p-polarized light. The reflectance curves for angular interrogation are plotted and the results are obtained in terms of sensitivity, detection accuracy, and quality factor. The significantly high sensitivity and detection accuracy for Oliguria distinguishes it from Polyuria having lower sensitivity.

Plasmophore Enhancement in Fibroblast Green Fluorescent Protein-Positive Cells Excited by Smoke.

Considering the large consumption of nicotine and its sedative/stimulant effect on different organs of the body, the detection of low concentration of this material and its subsequent effect on live animals plays a significant role. Optical detection techniques such as plasmonics are the pioneers in highly sensitive detection techniques. However, for investigating the nicotine/smoke effect on live cells, not only the interaction between cell nicotine should be optimized but also the plasmonic interface should show a high sensitivity to the reception of nicotine by the cell receptors. In this study, the sensitivity of the plasmonic detection system was greatly increased using the coupling of plasmon and fluorophore. This coupling could enhance the main plasmonic signal several orders of magnitude besides improving Δ and Ψ ellipsometry parameters. Benefiting from the green fluorescence proteins, the phase shift and the amplitude ratio between the reflections under s- and p-polarized light enhance considerably which verifies the coupling of the dipole of the fluorescence emitter and the plasmons of the metal nanostructure. For 1 s increase of the maintenance time, we encountered a considerable increase in the Δ values that were 0.15° for Te = 1 s and 0.24° for Te = 3 s. Benefiting from extracted ellipsometry parameters, this study could open new avenues toward studying the effect of various types of drugs and stimulants on biological samples using a novel plasmophore platform.

Surface Plasmon Resonance of Au Thin Films Modified By Catalyst Monolayer

In this talk, we present the results and modeling o the catalyst monolayer modification effects on plasmon resonance of Au thin films. The experiments are conducted using an attenuated total reflection arrangement in which p-polarized light is incident through a prism onto a thin (-400 A) Au film deposited on the mica substrate. (Kretschmann configuration [[1]]). The angle of incidence on the base of the prism is greater than the critical angle for the prism: electrolyte interface and SPs are excited by the evanescent wave generated under these conditions of total internal reflection. The excitation is manifested by a decrease in the intensity of reflected light. The Pd monolayer on Au were electrodeposited using procedure reported by Kolbe et al [[2],[3]], while the Pt submonolayer/monolayers were deposited on Au using Surface Limited Redox Replacement (SLRR) of Pb UPD monolayer [[4]]. The plasmon resonance frequency of Au(hkl), PdML/Au(hkl) and PtML/Au(hkl) and PtSML/Au(hkl) were investigated as a function of the applied potential in the range between -0.24 V to 0.4 V vs. SCE. The comparative analysis, between Au and catalyst monolayer modified Au(hkl) samples indicate that SP resonant frequency change is induced by both; surface charge and dipole moment of the surface as well as he adsorption of H on the catalyst monolayer surface in the UPD region. The latter effect is quantified using subtractive analysis between the Au and catalyst modified Au surface and solutions with different pH. In conclusion, we present a simple model describing the catalyst monolayer effect on plasmon resonance of Au films. [1] E. Kretschmann and H. Raether, Z. Natutforsch. 23a (1968) 2135. [2] L.A. Kibler, M. Kleinert, R. Randler, D.M. Kolb, Surface Science, 443 (1999) 19. [3] J. Tang, M. Petri, L.A. Kibler, D.M. Kolb, Electrochimica Acta, 51, (2005) 125 [4] K. Sasaki et al, Electrochim. Acta, 55, (2010) 2645.

Total Internal Reflection Tip-Enhanced Raman Spectroscopy of Cytochrome c.

Surface and tip-enhanced Raman spectroscopies in total internal reflection (TIR-SERS and TIR-TERS) are used to characterize the oxidation, spin, and ligation state of cytochrome c (Cc) molecules electrostatically bound on a hydrophilic thiol self-assembled monolayer. TIR-SERS spectra of this model hemoprotein show marker bands typical of the 6cLS ferric state of Cc. The performances of the TIR-TERS technique as a function of the incidence angle are described, showing in particular a significant electromagnetic enhancement of the Raman signal under p-polarized light excitation. TIR-TERS spectra of Cc confirm the 6cLS ferric state assignment deduced from TIR-SERS spectra, thus demonstrating the possibility of probing with nanoscale spatial resolution the 6cLS oxidized form of Cc that is potentially implicated in cell apoptotic processes. The minimal far-field contribution of the sample in TIR-TERS also offers promising perspectives for future nanoscale chemical characterizations of photosensitive biomolecules in complex biological media.

Precise laser trimming of alloy strip resistor: A comparative study with femtosecond laser and nanosecond laser

Laser trimming has become one of the powerful tools for precise manufacturing of alloy resistors that are widely used in electrical vehicles, electrical controlling, and in appliances. In this work, the influence of femtosecond laser trimming is compared with nanosecond laser trimming. The authors found that lasers focused on different heights relative to the sample surface induced significant changes in surface morphologies. The resistance change was systematically investigated as a function of cutting lengths and cutting depths of different laser powers for both lasers. The experiments display that femtosecond laser trimming has a higher precision of the resistance adjustment than nanosecond laser trimming. The periodic ripple structure by the femtosecond laser was investigated at the focus position above, onto, or beneath the surface. The period of a low frequency ripple structure (LFRS) on the ablated groove bottom is about 600–700 nm when the laser focuses just right on the surface but changes to 490–560 nm when focusing above or beneath the surface. The period of a high frequency ripple structure is about 100–380 nm at the vertical direction of LFRS. The period of low frequency ripple on the outside of the groove is smaller than that on the groove bottom for all three focusing cases. The period of the LFRS is not sensitive to the laser power. The range of the resistor value change in the s-polarized light direction of the femtosecond laser is more than that in the p-polarized light direction.

The use of plasmon resonance spectroscopy to analyze the parameters of thin layers

The paper presents the results of calculating the angular spectra of ellipsometric parameters and ellipse parameters upon reflection of right-polarized light onto the Kretchman layered system under conditions of excitation of surface plasmons at the boundary of the silver metal layer. It is shown that the studied parameters turn out to be very sensitive when a film of the material under study is placed in a layered system. The conditions are found under which a change in the nature of the polarization of the reflected wave occurs - from the right circular wave of the incident wave to the left elliptical in reflected light. Thus, the use of circular polarization and ellipsometry in plasmon resonance spectroscopy expands the possibilities of this method, in which only the energy reflection coefficient of p-polarized light is studied.

Coherent perfect absorption in epsilon-near-zero ITO thin film in near infrared

Perfect absorption is one of the important application of epsilon-near-zero (ENZ) material. We analyze here the coherent perfect absorption (CPA) in single and bilayer of ENZ thin film of ITO by admittance matching method. To enhance the absorption, a coupling layer of dielectric is to deposit on the substrate with an ENZ ITO layer. CPA conditions are presented here in simulation results which are obtained for p-polarized light. This mode is comparable with the transverse resonance effect. In order to obtain the symmetric results, the optimum polarization direction of illumination is also extracted here. Employing the ENZ CPA property of ITO, this structure is applicable in optical switching, modulation and sensor at the telecommunication regime.

Hot Electron Driven Photocatalysis on Plasmon-Resonant Grating Nanostructures.

We demonstrate the hot electron injection of photoexcited carriers in an Ag-based plasmon resonant grating structure. By varying the incident angle of irradiation, sharp dips are observed in the reflectance with p-polarized light (electric field perpendicular to grating lines) when there is wavevector matching between the incident light and the plasmon resonant modes of the grating and no angle dependence is observed with s-polarized light. This configuration enables us to compare photoelectrochemical current produced by plasmon resonant excitation with that of bulk metal interband absorption simply by rotating the polarization of the incident light while keeping all other parameters of the measurement fixed. With 633 nm light, we observed a 12-fold enhancement in the photocurrent (i.e., reaction rate) between resonant and nonresonant polarizations at incident angles of ±7.6° from normal. At 785 nm irradiation, we observed similar resonant profiles to those obtained with 633 nm wavelength light but with a 44-fold enhancement factor. Using 532 nm light, we observed two resonant peaks (with approximately 10× enhancement) in the photocurrent at 19.4° and 28.0° incident angles, each corresponding to higher order modes in the grating with more nodes per period. The lower enhancement factors observed at shorter wavelengths are attributed to interband transitions, which provide a damping mechanism for the plasmon resonance. Finite difference time domain (FDTD) simulations of these grating structures confirm the resonant profiles observed in the angle-dependent spectra of these gratings and provide a detailed picture of the electric field profiles on and off resonance.

The X-Ray Emission Effectiveness of Plasma Mirrors: Reexamining Power-Law Scaling for Relativistic High-Order Harmonic Generation

Ultrashort pulsed lasers provide uniquely detailed access to the ultrafast dynamics of physical, chemical, and biological systems, but only a handful of wavelengths are directly produced by solid-state lasers, necessitating efficient high-power frequency conversion. Relativistic plasma mirrors generate broadband power-law spectra, that may span the gap between petawatt-class infrared laser facilities and x-ray free-electron lasers; despite substantial theoretical work the ultimate efficiency of this relativistic high-order-harmonic generation remains unclear. We show that the coherent radiation emitted by plasma mirrors follows a power-law distribution of energy over frequency with an exponent that, even in the ultrarelativistic limit, strongly depends on the ratio of laser intensity to plasma density and exceeds the frequently quoted value of −8/3 over a wide range of parameters. The coherent synchrotron emission model, when adequately corrected for the finite width of emitting electron bunches, is not just valid for p-polarized light and thin foil targets, but generally describes relativistic harmonic generation, including at normal incidence and with finite-gradient plasmas. Our numerical results support the ω−4/3 scaling of the synchrotron emission model as a limiting efficiency of the process under most conditions. The highest frequencies that can be generated with this scaling are usually restricted by the width of the emitting electron bunch rather than the Lorentz factor of the fastest electrons. The theoretical scaling relations developed here suggest, for example, that with a 20-PW 800-nm driving laser, 1 TW/harmonic can be produced for 1-keV photons.

The new structure of analytical and semi-analytical solutions of the longitudinal plasma wave equation in a magneto-electro-elastic circular rod

This research paper extracts novel analytical and semi-analytical wave solutions of the longitudinal wave equation in a magneto-electro-elastic circular rod by using the modified Khater method as one of the most novel and general computational methods and the Adomian decomposition method as a semi-analytical method. The longitudinal waves in metallic thin films are explained for the first time by Nilsson and Lindau, who used the visual evidence. They noted subdued anomalies in the ports of thin ([Formula: see text]100 Å) Ag layers deposited on amorphous silica for p-polarized light at frequencies padlock to the dynamic plasma frequency. These properties are studied by our two suggested methods and are explained by sketching some of our obtained solutions. Moreover, the stability property is tested for our obtained solutions by using the features of the Hamiltonian system. The performance of our used methods shows the power and effectiveness of these methods and their ability to apply on many different forms of nonlinear partial differential equations.

Near-infrared optical absorption in GaN/AlN quantum wells grown by molecular-beam epitaxy

Optical absorption of s- and p-polarized light was studied in GaN/AlN quantum wells in the near-infrared spectral range. An absorption peak associated with intersubband electron transitions in quantum wells was observed near a wavelength of 1.55 μm. Optoelectronic devices based on these structures can be used in fiber-optic telecommunication technologies.

Excitation of surface plasmon–polariton waves in the prism-coupled configurations guided by reciprocal, uniaxially chiral, bianisotropic material

Excitation of the surface plasmon–polariton (SPP) waves guided by the planar interface of a metal and a reciprocal, uniaxially chiral, bianisotropic material was investigated. The characteristics of SPP waves in two prism-coupled configurations were observed and also verified by the spatial profiles when the waves were guided by the interface perpendicular to the direction of the chirality and uniaxiality. The SPP waves were found to be neither p- nor s-polarized in nature when the chirality parameter was large. The SPP wave was excited in the Turbadar–Kretschmann–Raether (TKR) configuration by p-polarized incident light only, that also when the real part of the chirality parameter was smaller than a threshold value. The excitation of SPP wave was not supported by s-polarized incident light in the TKR configuration. However, the excitation of SPP wave was found in the Turbadar–Otto configuration for both the p-polarized incidence and the s-polarized incidence.

High-Efficiency Backlight Effectively Using P-polarized Light at the Interface of Refraction

High-Efficiency Backlight Effectively Using P-polarized Light at the Interface of Refraction

Surface plasmon based 1D-grating device for efficient sensing using noble metals

This study presents the design and optimization of device with 1D nanostructured grating modeled on gold (Au), silver (Ag) and copper (Cu) for sensing a minor variation in refractive index (RI). This small change in the adjacent media to metallic grating is detected quite effectively using the unique characteristic of the surface plasmon polaritons (SPPs). The electric field (E-field) of the SPPs penetrates into the nearby media which is very sensitive to slight change in RI. The grating devices has been simulated by using COMSOL Multiphysics 5.3a with periodicity 700 nm, film thickness 50 nm and optimum slit width 300 nm in correspondence with fundamental plasmonic mode. The 0th order transmission spectra have been extracted from each grating device by illuminating (through the substrate side) with p-polarized light at normal incidence. The change in RI of analyte studied to have a significant effect on the resonance wavelength. The sensitivity has been calculated as 700, 731 and 722 nm/RIU for Au, Ag and Cu grating devices respectively which is remarkable. The stability and quick sensing of Au-device make it suitable for application besides some other deficiencies (e.g. slightly less sensitivity as compared to Ag) which should be compromised. Near field analysis has been performed to apprehend the underlying physics connected with each resonance. The highest value of electric and magnetic fields (E-field and H-field) are obtained in the case of Au grating indicating the most efficient excitation of SPPs. This confirms the reasoning behind the efficient sensitivity of Au grating device and finds applications in medicine.

Efficient planar plasmonic directional launching of linearly polarized light in a catenary metasurface

Efficient directional excitation of planar surface plasmon polaritons (SPPs) has important and wide applications in micro-nano photonic technology. Recently, by using the geometric phase and spin-orbit interaction, catenary structures have been applied to the directional control of SPPs and showed excellent performance. However, due to the need to use the chirality of the subwavelength catenary apertures, the previously studied systems were only suitable for circularly polarized light. Here, based on a catenary metasurface we theoretically design and experimentally demonstrate a SPP directional launcher used for linearly polarized light. The numerical calculation results show that the directional extinction ratio reaches up to 35 dB under the normal incidence of p-polarized light at 750 nm which is 5 dB higher than the maximum extinction ratio in the existing results as we know. The experimental results show that the resonant wavelength position, bandwidth and extinction ratio change trend well match the theoretical results. The physical mechanism is analyzed and it is found that the asymmetric quadrupole mode is the key factor leading to the directional SPPs which is completely different from the geometric phase modulation mechanism to excite the directional SPPs of circularly polarized light in the catenary metasurface. These principles and methods could open new doors for future chip-level photonic device or system design such as multi-directional beam splitters and polarization detectors.

Plasmonic Contrast Imaging Biosensor for the Detection of H3N2 Influenza Protein-Antibody and DNA-DNA Molecular Binding

We report a plasmonic contrast imaging biosensor, RESONATOR. It measures the intensity difference between the p-and s- polarization images at plasmonic excitation. At plasmonic resonance, only the p-polarization light is excited, while s-polarization light remains the same. Image intensity subtraction between both polarizations can eliminate common system noise and enhance sensor resolution. In refractive index measurements, the sensor resolution was found to be $4.36 \times 10^{-7}$ RIU. The plasmonic contrast imaging sensor has further been demonstrated for H3N2 influenza antibody detection and DNA-DNA molecular binding detections. The detection limit was found to be 8.6nM (320 ng mL-1) for H3N2 influenza antibodies. This value is 56% and 216% better than the detection limit reported for influenza antibody detection with commercial Biacore systems. A computer controlled device prototype has further been developed based on the optical design, which is ready for various bio-molecular binding detections in medical diagnosis, drug discovery, biological study and environmental monitoring.