Total Internal Reflection Mode Research Articles

Admittance loci based design of nanoplasmonic sensor using ceramic and chalcogenide materials

A prism coupler based nanoplasmonic sensor consisting of prism, gold (Au) metal film and dielectric sample has been investigated with the use of admittance loci method in Attenuated Total Internal Reflection (ATIR) mode. Prism materials namely ceramic and chalcogenide (2S2G) have been used to investigate their effects on surface plasmon resonance (SPR) based sensing at 670nm wavelength by admittance loci plots and also by corresponding surface plasmon sensing curves. The performance of the nanoplasmonic sensor based on the choice of ceramic and chalcogenide (2S2G) as coupling prism materials have been discussed with the help of sensor performance parameter plots giving emphasis on the dynamic range of the proposed nanoplasmonic sensor.

Effect of Different Plasmon Active Metals on Admittance Loci Based Design of a Plasmonic Sensor

A Kretschmann type plasmonic structure consisting of a fused silica glass prism, plasmon active metal film and dielectric sample has been investigated with the use of admittance loci method in attenuated total internal reflection mode. Different plasmon active metals have been used to study their effect on surface plasmon resonance (SPR) sensing (at 633 nm wavelength of He–Ne light) by admittance loci plots and also by corresponding SPR sensing curves. The performance of the plasmonic structure based on the choice of plasmon active metal has been discussed with the help of sensitivity and figure of merit plots giving emphasis on the dynamic range of the designed plasmonic structure. Simulations have been carried out in MATLAB 7.1 environment.

Performance of admittance loci based design of plasmonic sensor at infrared wavelength

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.

Modelling of chalcogenide glass based plasmonic structure for chemical sensing using near infrared light

A simulation study about the use of admittance loci method in surface plasmon resonance (SPR) based sensing using chalcogenide and other commonly used glasses have been reported in this paper. A simple Kretschmann–Raether prism-based multilayer structure consisting of a glass prism, gold (Au) metal film layer and water (sensing layer) has also been investigated with the use of admittance loci method in attenuated total internal reflection (ATIR) mode. Commonly used glasses along with chalcogenide glass have been used to study their effect on SPR sensing (at 900nm wavelength) in near infrared region by corresponding admittance loci plots and also by SPR sensing curves.

Effect of prism material on design of surface plasmon resonance sensor by admittance loci method

A theoretical study on the design of surface plasmon resonance (SPR) based sensor by admittance loci method has been reported in this paper with the main emphasis being given to the effect of the prism material in a conventional Kretschmann structure in attenuated total internal reflection (ATIR) mode. Several sensing media such as water, acetone, methanol etc have been investigated using different types of prism materials to study their effect on SPR sensing and validated by corresponding admittance loci plots as well as respective SPR curves. The performance of the sensor based on choice of the prism material has been discussed with the help of sensitivity plots giving due to the importance of dynamic range of the designed sensor. Simulations have been carried out in MATLAB 7.1 environment.

Benefits of Photonic Bandgap Fibers for the Thermal Stabilization of Optoelectronic Oscillators

This work reports on the analysis of optoelectronic oscillators (OEO) realized with various kinds of microstructured optical fibers (MOF) as delay lines. More precisely, the thermal dependence of the group delay is measured through the analysis of the thermal variation of the frequency of the OEO and compared with a theoretical model that includes the effect of temperature on refractive index, strains, and deformation. It is shown that, whereas the presence of air in air/silica fibers guiding via modified total internal reflection (M-TIR) has only little interest, it allows a net decrease of the thermal variation of the group delay in the case of hollow core photonic bandgap (HC-PBG) fiber. In addition to the effect of material, we show that this decrease is related to the PBG mechanism itself, which is a property also exploited in a solid-core photonic bandgap (SC-PBG) fiber.

Ellipsometry study on gold-nanoparticle-coated gold thin film for biosensing application

The amplified plasmonic response from various distributions of gold nanoparticles (AuNPs) coated on top of gold thin film was studied via ellipsometry under total internal reflection mode. The surface plasmon resonance dip can be tuned from the visible to near infrared by simply varying the AuNP concentration. Theoretical modeling based on effective medium theory with a multi-slice model has been employed to fit the experimental results. Additionally, this experimental tool has been further extended to study bio-molecular interactions with metal surfaces as well as in studying protein-protein interaction without any labeling. Hence, this technique could provide a non-destructive way of designing tunable label-free optical biosensors with very high sensitivity.

Detection of Aflatoxin B1 with a Label-Free Ellipsometry Immunosensor

The method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was utilised for detection of Aflatoxin B1. The method of TIRE with the improved data analysis was capable of detection of aflatoxin molecules in low concentrations (down to 0.04 ng/ml) using a label-free and cost-effective direct immunoassay format. TIRE study of the binding kinetics yielded a large value of the association constant in the range of 106 l mol−1 which is typical for highly specific immune reactions. The comparison of the experimental data for three mycotoxins studied (e.g. aflatoxin B1, T-2 mycotoxin, and zearalenone) confirmed a common mechanism of the sensitivity boost due to the aggregation of hydrophobic molecules of mycotoxins in aqueous solutions.

Development of biosensor based on imaging ellipsometry and biomedical applications

So far, combined with a microfluidic reactor array system, an engineering system of biosensor based on imaging ellipsometry is installed for biomedical applications, such as antibody screen, hepatitis B markers detection, cancer markers spectrum and virus recognition, etc. Furthermore, the biosensor in total internal reflection (TIR) mode has be improved by a spectroscopic light, optimization settings of polarization and low noise CCD which brings an obvious improvement of 10 time increase in the sensitivity and SNR, and 50 times lower concentration in the detection limit with a throughput of 48 independent channels and the time resolution of 0.04S.

Detection of β-amyloid peptide (1–16) and amyloid precursor protein (APP 770) using spectroscopic ellipsometry and QCM techniques: A step forward towards Alzheimers disease diagnostics

A highly sensitive method of spectroscopic ellipsometry in total internal reflection mode (TIRE) was exploited for detecting β-amyloid peptide (Aβ 1–16) in the direct immune reaction with monoclonal DE2 antibodies (raised against Aβ 1–16) electrostatically immobilised on the surface of gold. A rapid detection of Aβ 1–16 in a wide range of concentrations from 5 μg/ml down to 0.05 ng/ml was achieved using a cost-effective and label-free direct immunoassay format. TIRE dynamic spectral measurements proved that the immune reaction between DE2 monoclonal antibodies and Aβ 1–16 is highly specific with the affinity constant K D = 1.46 × 10 −8 mol/l . The same DE2 antibodies were utilised for detection of amyloid precursor protein APP 770, a larger protein containing Aβ 1–16 domain, using the quartz crystal microbalance (QCM) measurements in liquid. A combination of QCM and TIRE kinetics results allowed the evaluation of the originally unknown concentration of APP 770 in complete medium solution containing other proteins, salts, and amino acids.

Doping-Induced Conductivity Transitions in Molecular Layers of Polyaniline: Optical Studies of Electronic State Changes

The doping-induced conductivity transitions in molecular layers of polyaniline have been studied by monitoring the correlated optical and spectroscopic changes using spectroscopic and single wavelength extinction ellipsometry, also in total internal reflection mode (TIRE), together with reflection spectrometry. The measurements were performed on deposited multilayers as well as on a Langmuir monolayer at the air-water interface, as a function of acidic doping. We found that the characteristic spectroscopic features of conducting and insulating polyaniline persisted down to the single layer, both in the solid state and at the air-water interface. We also investigated in real time the modulation of conductivity induced by the intercalation of Li ions in the polyaniline film, by a combination of time-resolved ellipsometry and reflectivity spectra measurements. In this case, the enhanced sensitivity provided by the TIRE geometry, combined with the relatively fast time scale accessible by the single wavelength ellipsometry, allowed us to follow in detail in real time the doping/dedoping process.

Super-resolution video microscopy of live cells by structured illumination.

Structured-illumination microscopy can double the resolution of the wide-field fluorescence microscope, but has previously been too slow for dynamic live imaging. Here we demonstrate a high-speed SIM that is capable of 100 nm resolution at frame rates up to 11 Hz for several hundred time frames. We demonstrate the microscope by video imaging of tubulin and kinesin dynamics in living Drosophila S2 cells in the total internal reflection (TIRF) mode.

Injection-seeded internal-reflection-mode p-Ge laser exceeds 10W peak terahertz power

Injection seeding of a large active p-Ge laser crystal operating on total internal reflection modes is demonstrated with peak output power at the level of 40W in the 1.5–4.2THz spectral range. The improvement over traditional 1W axial mode p-Ge lasers is due both to spatially and temporally more efficient use of the available population inversion.

Effective Index and Mode Width Sensitivities to Opto-Geometrical Parameters on Index-Guided Photonic Crystal Fibers

The effective index and fundamental mode width behavior on modified total internal reflection (MTIR) photonic crystal fibers is studied in a wide normalized frequency (Lambda/lambda) area. The sensitivities to the structural and opto-geometrical parameters are obtained and the higher sensitivity region is clearly identified. The fabrication tolerance expression is also shown. Conclusions from this letter will be useful for designing and fabrication processes, also for using MTIR fibers on optical devices such sensors.

A Microfluidic Chip Based on Localized Surface Plasmon Resonance for Real-Time Monitoring of Antigen–Antibody Reactions

Localized surface plasmon resonance (LSPR) connecting to noble metal nanoparticles is an important issue for many analytical and biological applications. Therefore, the development of microfluidic LSPR chip that allows studying biomolecular interactions becomes an essential requirement for micro total analysis systems (µTAS) integration. However, miniaturized process of the conventional surface plasmon resonance system has been faced with some limitations, especially with the usage of Kretschmann configuration in total internal reflection mode. In this study, we have tried to solve this problem by proposing a novel microfluidic LSPR chip operated with a simple collinear optical system. The poly(dimethylsiloxane) (PDMS) based microfluidic chip was fabricated by soft-lithography technique and enables to interrogate specific insulin and anti-insulin antibody reaction in real-time after immobilizing antibody on its surface. Moreover, the sensing ability of microfluidic LSPR chip was also evaluated with various glucose concentrations. The kinetic constant of insulin and anti-insulin antibody was determined and the detection limit of 100 ng/mL insulin was archived.

Even illumination in total internal reflection fluorescence microscopy using laser light

In modern fluorescence microscopy, lasers are a widely used source of light, both for imaging in total internal reflection and epi-illumination modes. In wide-field imaging, scattering of highly coherent laser light due to imperfections in the light path typically leads to nonuniform illumination of the specimen, compromising image analysis. We report the design and construction of an objective-launch total internal reflection fluorescence microscopy system with excellent evenness of specimen illumination achieved by azimuthal rotation of the incoming illuminating laser beam. The system allows quick and precise changes of the incidence angle of the laser beam and thus can also be used in an epifluorescence mode.

Biosensor with total internal reflection imaging ellipsometry

In order to monitor multiple protein reaction processes simultaneously, a biosensor based on imaging ellipsometry operated in the total internal reflection mode is proposed. It could be realised as an automatic analysis for protein interaction processes with real-time label-free method. Its principle and methodology as well as a demonstration for its applications are presented.

Light beam output from diamond-shaped total-internal reflection modes by using intracavity air gaps

We propose a novel method for extracting light beams from diamond-shaped total-internal reflection modes in two-dimensional microcavity laser diodes by the use of intracavity air gaps. By fabricating such a laser diode, we experimentally demonstrate that the direction and longitudinal mode spacing of the output beams are in good accordance with theoretical calculations.

Laser nanochemistry

Abstract Various time- and space-resolved spectroscopies have been developed and applied to thin films and nanoparticles. Dynamic reflection spectroscopies of total internal, diffuse, and regular reflection modes analyze photophysical and photochemical processes at the interface/surface layers with thicknesses of a few tens to a few hundreds of nm and of optically scattering materials. The excited singlet, triplet, and ionic states are identified, and intersystem crossing, isomerization, electron transfer and recombination, and photothermal conversion due to excited-state annihilation are analyzed, just as by transmittance mode spectroscopy. Fluorescence and Rayleigh light-scattering spectroscopies are developed for elucidating excited-state dynamics of single nanoparticles. The optical properties are related to their size, shape, internal structure, and environmental conditions. We prove that organic molecular materials show novel nanometer-size effects due to structural confinement. The high-intensity laser excitation induces ablation whose dynamics and mechanism are considered on the basis of time-resolved spectroscopy and imaging. For nanosecond and femtosecond ablation, we propose cyclic multiphotonic absorption and photomechanical mechanisms, respectively, while purely photochemical ablation was confirmed. Ablation studies have opened a new research approach toward expansion and contraction dynamics of polymer films, nanoparticle preparation, crystal growth control, crystallization in saturated solution, and others.

Behavior of phosphatidylcholine adsorption on CNx coated PTFE films

In order to expand the applicability of PTFE for artificial replacement, the CNx coatings which could influence lipid adsorption are of considerable relevance. The intention of this study is to gain first information about the influence of CNx coating on the phosphatidylcholine (PC) adsorption of PTFE. By means of ion beam assisted deposition (IBAD), the CNx films can have a strongly bond to the PTFE substrates as a wide atomic intermixed zone that is formed at the surface. The characterization of the CN structures under different bombarding conditions was carried out by Raman and SEM as well as XPS measurements. For characterizing the behavior, analysis of PC adsorption was illuminated where Fourier transform infrared spectroscopy of attenuated total internal reflection mode (ATR-FTIR) was used as principal instrument. Results point to an increase of nitrogen content and sp2/sp3 fraction under higher bombarding voltage which seems to play a dominant role for the biological characters and a dramatic restraining of lipid deposition was induced on CNx coated PTFE compared with the uncoated samples.