Total Internal Reflection Condition Research Articles

Factors that influence confocal apertureless near-field scanning optical microscopy

We demonstrate several influences of a silicon probe of an atomic-force microscope on the fluorescence of single CdSe/ZnS quantum dots on a glass cover slip, measured in a confocal apertureless scanning near-field optical microscope (ANSOM): (a) probe-induced fluorescence quenching with the polarization of excitation orthogonal to probe axes; (b) changes in fluorescence enhancement as the quantum yield of a quantum dot fluctuates (the fluorescence enhancement is much larger in a low quantum yield state); (c) the probe-quantum dot optical interaction depends on very local and sometimes non-uniform optical properties of the probe; some fluorescence ANSOM images of quantum dots are asymmetrical and shifted with respect to topographical images; and (d) probe pressure, not the optical near-field, bleaches quantum dot fluorescence during vertical probe scans, or when the microscope operates in dynamic-force mode and the probe tip taps the sample. The fluorescence measurements have been done using a confocal ANSOM with 10–12% fluorescence collection efficiency under total internal reflection conditions of excitation.

Highly sensitive detection of molecules at the liquid/liquid interface using total internal reflection–optical beam deflection based on photothermal spectroscopy

In this study, a highly sensitive and versatile method based on photothermal spectroscopy has been developed to monitor the molecular density at a liquid/liquid interface. The excitation under the total internal reflection (TIR) condition results in a formation of a thin thermal lens elongated along the interface. In order to measure the thermal lens effects effectively and to reduce the background, the probe beam is irradiated parallel to the interface and its deflection is detected, which is called an TIR-optical beam deflection (TIR-OBD). As a result, the detection limit in TIR-OBD is about 2 orders lower than that of TIR-thermal lens spectroscopy, in which the irradiation of the probe beam is perpendicular to the interface.

Combined evanescent light–electrostatic atom trap of subwavelength size

A new combined evanescent light–electrostatic atom trap is proposed. Cold atoms repulse from the evanescent wave of the blue-detuned (quasi) resonant laser light formed in the total internal reflection conditions and electrostatically attract to the sharp conducting tip located close to the glass–vacuum interface. It is shown that a few milliKelvin deep and subwavelength-size traps can be formed with such an approach. These traps can be easily “scaled” by using an array of tips, which makes them a perspective object for applications in quantum computing.

New water shock sensor

A new shock sensor for liquids is described in this article which is suitable for precise shock Hugoniot compression curve measurement of water in the relatively low pressure region of ⩽1 GPa. The present method is based on the fact that the refractive index of water has a very large pressure dependence. A laser beam incident on the liquid–glass boundary from the proper angle of incidence is totally reflected at the interface. The condition of total internal reflection is violated if the refractive index changes instantaneously by shock compression. The shock target assembly was designed for a gas gun experiment based on the above concept. Two examples of the shock Hugoniot measurement data of water were given.

Aberrationless approach for diffraction of pulses at linear interfaces

The diffraction of temporally Gaussian shaped light pulses is theoretically studied by means of the aberrationless approach, a theoretical technique previously used for spatially bounded beams of unlimited time extension and which is extended here to time domain. We consider linear interfaces, that is, we assume that the spectral components of the vector field in the diffracted pulse are linearly related with the spectral components of the vector field in the incident pulse. In our analysis pulse deformations are described in terms of the following effects: time delay, focal displacement, waist modification and change in propagation velocity. Expressions for these effects, the time domain analogues of those already reported in the spatial domain, are given and compared with those obtained using the stationary phase method. The theory is used to calculate deformations of a short light pulse at a flat interface near conditions of total internal reflection.

Simulation of near-field photolithography using the finite-difference time-domain method

Illuminating a transparent mold under total internal reflection condition generates evanescent light. Near-field photolithography uses such light, and we simulated this exposure in two dimensions using the finite-difference time-domain (FDTD) method. Our simulation suggests the feasibility of resolving a 130 nm pitch grating pattern, which is finer than the diffraction limit of light. The simulation results showed fair agreement with our experimental results, confirming the strong influence of exposure light polarization to the distribution of optical near fields in photoresist films. This indicates that the FDTD simulation is promising to predict exposure results for designing molds. We further extended the simulation varying the thickness and refractive index of a photoresist film. Based on the simulation results, showing the good exposure contrast in the thin surface layer of the photoresist film, we suggested two methods to resolve a thick resist film: the multilayer resist method which allows us to use a sufficiently thin photoresist film, and the surface imaging technology which can completely dry develop a thick photoresist film even if its exposure area is confined in the surface layer.

Analysis of polarization effects on nanoscopic objects in the near-field optics.

This paper deals with the analysis of polarization around nanoscopic objects in near-field optics. The objects are illuminated through a transparent glass substrate under the condition of total internal reflection. The use of dielectric and metallic materials in the optical images is discussed. Using numerical simulations based on the Green's dyadic technique, we compute the total transmitted intensity of the scattered light and the different Cartesian components associated with the electric field in the attenuated total reflection configuration at constant height. The role of localized plasmon resonance is brought to the fore in the optical images of nanoscopic metallic objects. This paper shows that it is possible to reduce the interferences due to backward scattering from nanoscopic objects thanks to this polarimetry analysis.

Analysis and numerical simulation of eigenmode characteristics for semiconductor lasers with an equilateral triangle micro-resonator

The eigenmodes confined in the equilateral triangle resonator (ETR) are analyzed by deriving the eigenvalues and the mode field distributions and by the finite difference time domain (FDTD) technique. The analytical results show that the one-period-length for the mode light rays inside the ETR is the perimeter of the ETR, and the number of transverse modes is limited by the condition of total internal reflection. In addition, the sum of the longitudinal mode index and the transverse mode index should be an even number, which limits the number of confined modes again. Based on the FDTD technique and the Pade approximation, we calculate the mode resonant frequencies and the quality factors from the local maximum and the width of the spectral distribution of the intensity. The numerical results of mode frequencies agree very well with the analytical results, and the quality factor of the fundamental mode is usually higher than that of the higher order transverse modes. The results show that the ETR is suitable to realize single-mode operation as semiconductor microcavity lasers.

Polarization and spectroscopy analysis of the scattering by nanoscopic objects in the near-field optics

We show, in this article, the polarization effects around nanoscopic objects in the near-field optics. This analysis accounts of the variation of the total electric field intensity scattered by the objects with the incident wavelength. These are illuminated through a transparent glass substrate under the condition of total internal reflection. The use of different materials is discussed in the optical images according to the incident wavelength at constant height. Using numerical simulations based on the Green’s dyadic technique, we compute the total transmitted intensity of the scattered light in the attenuated total reflection configuration at constant height by varying the incident wavelength. The role of localized plasmon resonance is brought to the fore in the optical images for nanoscopic and metallic objects.

Near-field zone analysis of the Faraday rotation of magneto-optical thin films

This article studies, in the near-field zone, the magneto-optical Faraday effect of metallic multilayers illuminated under the condition of total internal reflection. We present numerical results obtained by the Green’s dyadic technique which depicts the distribution associated with each Cartesian component of the electric field inside, as well as outside, the magneto-optical structure. The Faraday rotation is found to increase significantly around the resonances associated either with plasmons or to interferences inside thin films.

Optical properties of multilayer structures

This paper describes the magneto-optical effects of metallic multilayers under the condition of total internal reflection. In the framework of the Green's dyadic technique, we present numerical simulations which account for the variation of the magneto-optical signal with the angle of incidence. The Attenuated Total Reflection (ATR) has become a new technique of characterization for thin films. We show, in this paper, optical effects due to a slight variation of the indice of refraction for thin dielectric films in reflection by the reflectivity and the Kerr rotation spectra of an optimized system. In transmission, this variation is brought to the fore by the near-field intensity spectra.

Light Scattering by Supported Metallic Nanostructures: Polarization and Spectroscopy in the Near-Field Zone

We show, in this paper, the analysis of polarization around nanoscopic objects in the near-field optics. The objects are illuminated through a transparent glass substrate under the condition of total internal reflection. The use of metallic materials (Al, Au) is discussed in the optical images. Using numerical simulations based on the Green's dyadic technique, we compute the total transmitted intensity of the scattered light and the different cartesian components associated to the electric field in the Attenuated Total Reflection configuration at constant height. The role of localized plasmon resonance is brought to the fore in the optical images for nanoscopic metallic objects (Au). This paper shows that it is possible to reduce the interferences due to the backward scattering on nanoscopic objects thanks to this analysis of polarization.

Effect of Surfactants on In-Plane and Out-of-Plane Rotational Dynamics of Octadecylrhodamine B at Toluene−Water Interface

We measured the time-resolved fluorescence anisotropy of N-octadecylrhodamine B (C18RB) at a toluene−water interface under the total internal reflection conditions (an incident angle of 70°), in the absence and presence of surfactants (Triton X-100 (TX-100), sodium dodecyl sulfate (SDS), or dihexadecyl hydrogen phosphate (DHP, pKa ≈ 2)). Without surfactants, the in-plane fluorescence anisotropy, rΦ, was almost 0 independent of time, and this implied that C18RB molecules rotated very fast (rotational correlation time, τΦ ≤ 1 ns) at the interface. In the nonionic TX-100 system, C18RB molecules rotated fast (τΦ ≤ 1 ns), but their rotational regions were restricted by the surfactant molecules. In the cases of SDS and deprotonated DHP systems, the interfacial concentration of the protonated C18RB, C18RBH+, increased with an increase in the surfactant concentration (1.0 × 10-10 − 5.0 × 10-8 M) by electrostatic attractive force. In these anionic surfactant systems, rΦ decreased exponentially with time and τΦ cou...

Magneto-optical Kerr effect in bilayer structures

This paper describes the magneto-optical effects and the reflectivity behaviors of bilayers based on magnetic and isotropic (MgF2)/anisotropic (TiO2) layers under the condition of total internal reflection. In the framework of Green's dyadic technique, we show accurately the optical properties of anisotropic layers deposited on a substrate. We present numerical simulations which account for the variation of angle of incidence at the HeNe laser wavelength. The Kerr rotation is found to increase significantly around the optical modes in total reflection. We also discuss the importance of anisotropic effects due to the crystallization of the dielectric material (TiO2) which occur in the reflectivity and Kerr rotation spectra.

Simultaneous measurement method of both shock state and stress profile in polymers in 1 GPa stress

A new procedure of recording both Hugoniot parameters and stress profile is proposed to study shock characteristics of polymers in 1 GPa stress region. The assembly consists of an in-material polyvinylidene fluoride (PVDF) stress gauge element and an optical prism pin. The PVDF gauge records the shock wave stress profile, while the prism pin records the arrival of shock front at the free surface of the target. Argon laser beam is focused onto the bottom face of the prism pin placed on the free surface so as to satisfy the condition of total internal reflection. Shock velocity can be estimated from the time difference of two signals, the PVDF gauge and the prism pin. The Hugoniot state can be calculated by the shock velocity and the projectile velocity regardless of the stress profile obtained by the PVDF gauge. A typical result for polytetrafluoroethylene (PTFE) specimen is shown with the impact velocity of PTFE flyer of 295 m/s. The obtained Hugoniot point coincides very well with the published data. Precision of the method was examined in detail, and estimated to be better than 2%.

Kerr and Faraday Rotations of Magneto-Optical Multilayers under the Condition of Total Internal Reflection

Kerr and Faraday Rotations of Magneto-Optical Multilayers under the Condition of Total Internal Reflection

Magneto-optical effects in multilayers illuminated by total internal reflection

This paper describes the magneto-optical effects of metallic multilayers under the condition of total internal reflection. In the framework of Green’s dyadic technique, we detail a practical and at time-consuming scheme to compute accurately the optical properties of anisotropic multilayers deposited on a substrate. We present numerical simulations which account for the variation of the angle of incidence at a fixed wavelength and for the variation of the wavelength at fixed angle of incidence. The Kerr rotation is found to increase significantly around the critical angle for total reflection. We also discuss the importance of plasmon effects in the structure of the Kerr rotation spectra. @S0163-1829~99!00708-0#

Printing Sub-100 Nanometer Features Near-field Photolithography

In this paper, a near-field photolithographic method which can realize ultra high resolution beyond the diffraction limit of light is described. Evanescent light generated on a transparent mold with a micro-relief illuminated on the condition of total internal reflection is used to expose a photoresist in contact with the mold. The plastic replica mold is flexible to eliminate the difficulty of close contact with the photoresist, and the replica mold damaged by the contact with the photoresist is disposable to maintain a high yield rate. We printed sub-100 nm features on a commercially available photoresist using 442-nm-wavelength light.

Guided-mode resonance absorption in partly oxidized thin silver films

Partly oxidized Ag films deposited on glass substrates were found to exhibit significantly different reflectance properties for either s- or p-polarized incident light under conditions of total internal reflection. The measured reflectances depend strongly on angle of incidence and wavelength of light and are sensitive functions of the Ag and Ag 2O layer thicknesses. For pure and slightly oxidized Ag films we observe the evolution of the well known surface plasmon resonance, whereas for Ag films with an increasing oxide layer a new resonance is observed in s-polarization. We account for all these effects by modeling the oxidized Ag film as a glass/Ag/Ag 2O/air system and using the recently published optical constants for Ag 2O.

Total internal reflection of backward volume magnetostatic waves and its application for waveguides in ferrite films

The problem of reflection of backward volume magnetostatic waves (BVMSWs) from a metallized portion of a ferrite film has been solved rigorously in the magnetostatic approximation. The condition of total internal reflection is formulated. This effect can be used for creation of a waveguide of BVMSWs. The waveguide is a slot in the metallic coating of a ferrite film with the slot's edges parallel to a magnetizing field. The use of such a waveguide makes it possible to avoid diffraction losses which accompany propagation of BVMSW beams in real devices. The BVMSW waveguide is convenient for connection with an active element (for example, with a Gunn diode). A simple method of calculating the dispersion characteristic of such a waveguide has been suggested. This characteristic is determined experimentally for some waveguides. The theoretical results and the experimental data are in reasonable agreement.