scispace - formally typeset
Search or ask a question

Showing papers on "Total internal reflection published in 2011"


Journal ArticleDOI
TL;DR: In this paper, the authors reviewed approaches to enhanced light extraction grouped into two sets depending on whether their application results in the change in the spontaneous emission rate or the angular distribution, or both.

284 citations


Journal ArticleDOI
TL;DR: In this article, a high-precision optical biosensor technique capable of independently determining the refractive index (RI) of liquids is presented, using photonic crystal surface waves (PC SWs) to detect surface binding events, while an independent registration of the critical angle was used for accurate determination of the liquid RI.
Abstract: A high-precision optical biosensor technique capable of independently determining the refractive index (RI) of liquids is presented. Photonic crystal surface waves (PC SWs) were used to detect surface binding events, while an independent registration of the critical angle was used for accurate determination of the liquid RI. This technique was tested using binding of biotin molecules to a streptavidin monolayer at various biotin concentrations. The attained baseline noise is 2×10−13 m/Hz1/2 for adlayer thickness changes and 8×10−8 RIU/Hz1/2 for RI changes.

209 citations


Journal ArticleDOI
TL;DR: This paper considers antireflective properties of textured surfaces for all texture size-to-wavelength ratios and investigates asymptotic behavior of the reflection with the change of the texture geometry for the long and short wavelength limits.
Abstract: In this paper, we consider antireflective properties of textured surfaces for all texture size-to-wavelength ratios. Existence and location of the global reflection minimum with respect to geometrical parameters of the texture is a subject of our study. We also investigate asymptotic behavior of the reflection with the change of the texture geometry for the long and short wavelength limits. As a particular example, we consider silicon-textured surfaces used in solar cells technology. Most of our results are obtained with the help of the finite-difference time-domain (FDTD) method. We also use effective medium theory and geometric optics approximation for the limiting cases. The FDTD results for these limits are in agreement with the corresponding approximations.

146 citations


Journal ArticleDOI
TL;DR: Experimental results predict a redshift in the resonance wavelength with the increase in the refractive index of the sensing layer for a given thickness of the silicon layer and the experimental results obtained on sensitivity match qualitatively with the theoretical results obtained using the N-layer model and the ray approach.
Abstract: We have experimentally studied the surface plasmon resonance (SPR)-based fiber-optic refractive index sensor incorporating a high-index dielectric layer using the wavelength interrogation method. Silver and gold have been used as SPR active metals followed by a high-index dielectric layer of silicon. Experimental results predict a redshift in the resonance wavelength with the increase in the refractive index of the sensing layer for a given thickness of the silicon layer. Further, as the thickness of the silicon layer increases, the sensitivity of the sensor increases. The upper limit of the silicon film thickness for the enhancement of the sensitivity has been found to be around 10 nm. The experimental results obtained on sensitivity match qualitatively with the theoretical results obtained using the N-layer model and the ray approach. The increase in sensitivity is due to the increase in the electric field intensity at the silicon-sensing-region interface. In addition to an increase in sensitivity, the silicon layer can be used to tune the resonance wavelength and can protect the metal layer from oxidation and hence can improve the durability of the probe.

146 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated wave transmission through an epsilon-near-zero metamaterial waveguide embedded with defects, and they showed that by adjusting the geometric sizes and material properties of the defects, total reflection and even transmission can be obtained, despite the impedance mismatch of the material with free space.
Abstract: In this work, we investigate wave transmission through an epsilon-near-zero metamaterial waveguide embedded with defects. We show that by adjusting the geometric sizes and material properties of the defects, total reflection, and even transmission can be obtained, despite the impedance mismatch of epsilon-near-zero material with free space. Our work can greatly simplify the design of zero-index material waveguide applications by removing the dependence on permeability.

128 citations


Journal ArticleDOI
TL;DR: A novel surface plasmon resonance (SPR) configuration based on narrow groove Plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration is presented.
Abstract: We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration. This eliminates the angular dependence requirements of SPR-based sensing and allows development of robust miniaturized SPR sensors. Simulations based on Rigorous Coupled Wave Analysis (RCWA) were carried out to numerically calculate the reflectance - from different gold and silver nano-grating structures - as a function of the localized refractive index of the media around the SPR nano-gratings as well as the incident radiation wavelength and angle of incidence. Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems. Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

98 citations


Journal ArticleDOI
TL;DR: The first measurement of the spin Hall effect of light (SHEL) on an air-metal interface is reported, which is a polarization-dependent out-of-plane shift on the reflected beam.
Abstract: We report the first measurement of the spin Hall effect of light (SHEL) on an air-metal interface. The SHEL is a polarization-dependent out-of-plane shift on the reflected beam. For the case of metallic reflection with a linearly polarized incident light, both the spatial and angular variants of the shift are observed and are maximum for -45°/45° polarization, but zero for pure s and p polarization. For an incoming beam with circular polarization states however, only the spatial out-of-plane shift is present.

88 citations


Patent
Takagi Masayuki1, Miyao Toshiaki1, Takahiro Totani1, Akira Komatsu1, Takashi Takeda1 
26 Aug 2011
TL;DR: In this paper, a virtual image display with brightness and high performance can be provided, where image light having a large total reflection angle in a light guide plate can be securely made incident on the image extraction part and efficiently extracted from the light exiting surface.
Abstract: Since a distance from an image extraction part to a light exiting surface is shorter downstream in an optical path than upstream in the optical path in relation to Z direction that is an arraying direction of reflection units, image light that propagates to pass between the image extraction part and the light exiting surface without becoming incident on the reflection units and therefore cannot be extracted to outside can be reduced. That is, since image light having a large total reflection angle in a light guide plate can be securely made incident on the image extraction part and efficiently extracted from the light exiting surface, light use efficiency in image formation can be enhanced. Thus, a virtual image display apparatus with brightness and high performance can be provided.

68 citations


Journal ArticleDOI
TL;DR: In this article, the lateral shifts of Dirac fermions in transmission through a monolayer graphene barrier were investigated, and it was shown that the lateral shift can be enhanced by the transmission resonances when the incidence angle is less than the critical angle for total reflection.
Abstract: The quantum Goos-Hanchen effect in graphene is found to be the lateral shift of Dirac fermions on the total reflection at a single p-n interface. In this paper, we investigate the lateral shifts of Dirac fermions in transmission through a monolayer graphene barrier. Compared to the smallness of the lateral shifts in total reflection, the lateral shifts can be enhanced by the transmission resonances when the incidence angle is less than the critical angle for total reflection. It is also found that the lateral shifts, as the function of the barrier's width and incidence angle, can be negative and positive in the cases of Klein tunneling and classical motion. The modulation of the lateral shifts can be realized by changing the electrostatic potential and induced gap, which gives rise to some applications in graphene-based devices.

58 citations


Journal ArticleDOI
TL;DR: It is shown that an arbitrarily thin metamaterial layer can perfectly absorb or giantly amplify an incident plane wave at a critical angle when the real parts of the permittivity and permeability of the metamMaterial are zero while the absolute imaginary parts can be arbitrarily small.
Abstract: In our common understanding, for strong absorption or amplification in a slab structure, the desire of reducing the slab thickness seems contradictory to the condition of small loss or gain. In this paper, this common understanding is challenged. It is shown that an arbitrarily thin metamaterial layer can perfectly absorb or giantly amplify an incident plane wave at a critical angle when the real parts of the permittivity and permeability of the metamaterial are zero while the absolute imaginary parts can be arbitrarily small. The metamaterial layer needs a totally reflective substrate for perfect absorption, while this is not required for giant magnification. Detailed analysis for the existence of the critical angle and physical explanation for these abnormal phenomena are given.

53 citations


Patent
30 Jun 2011
TL;DR: In this paper, a system and method for operating a light emitting device utilizing charged quantum dots is described, in which charged quantum dot are suspended in a liquid between an excitation plate and a cover plate.
Abstract: A system and method for operating a light emitting device utilizing charged quantum dots is described. In one embodiment, charged quantum dots are suspended in a liquid between an excitation plate and a cover plate. The excitation plate carries short-wave excitation light. Charged quantum dots near the surface of the excitation plate may emit light in response to an evanescent field generated by the short-wave excitation light undergoing total internal reflection within the excitation plate. The excitation plate and the cover plate may be coated with one or more transparent electrodes. The movement of charged quantum dots within the liquid may be controlled by applying one or more bias voltages to the one or more transparent electrodes. Light emission from a particular region near the surface of the excitation plate may be controlled by moving charged quantum dots into or out of the particular region.

Journal ArticleDOI
Igor Ravve1, Zvi Koren1
TL;DR: In this paper, an angle-based system was developed to define the interaction between incident and reflected waves at a specific image point, referred to as local angle domain (LAD), which consists of two subsystems: directional and reflection.
Abstract: We have developed an angle-based system, which defines the interaction between incident and reflected waves at a specific image point. We provide details about the technique used for angle-domain decomposition and imaging; in particular, the creation of two types of 3D subsurface angle gathers, as discussed in Part 1. The system, referred to as local angle domain (LAD) consists of two subsystems: directional and reflection. In the directional subsystem, the orientation of the ray-pair normal is represented by dip and azimuth. The reflection angle system is defined by the opening angle between the phase velocities of the incident and reflected rays, and by the opening azimuth, which describes the orientation of the ray-pair incidence plane measured in the ray-pair reflection plane. The directional angles are defined in a rotated local frame, and the opening azimuth is defined in the ray-pair reflection plane. The vertical axis of the local frame is collinear with a preset background normal to the physical ...

Journal ArticleDOI
TL;DR: Measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range show efficiencies in the range of ∼50-100% of theoretical predictions when taking the effects of the support mesh into account.
Abstract: We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 μm were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of ∼50–100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher.

Journal ArticleDOI
Qing Ye1, Jin Wang1, Zhichao Deng1, Wen-Yuan Zhou1, Chunping Zhang1, Jianguo Tian1 
TL;DR: An extended differential total reflection method is introduced to determine the complex refractive index of biotissue and the real part is directly determined by differential of the reflectance curve, and the imaginary part is obtained from nonlinear fitting.
Abstract: Refractive index of biotissue is a useful optical parameter in the biomedical field. An extended differential total reflection method is introduced to determine the complex refractive index. The real part is directly determined by differential of the reflectance curve, and the imaginary part is obtained from nonlinear fitting. The method is verified by a series of tissue-mimicking phantoms, porcine muscle and porcine adipose.

Journal ArticleDOI
TL;DR: The basic elements of EW-CRDS will be introduced and the relative merits of different configurations discussed, along with various aspects of instrumentation and design, and future developments and trends in EW-cavity based spectroscopy are predicted.
Abstract: Evanescent wave cavity ring-down spectroscopy (EW-CRDS) is a surface sensitive technique, which allows optical absorption measurements at interfaces with good time resolution. In EW-CRDS, a pulsed or modulated laser beam is coupled into an optical cavity which consists of at least one optical element, such as a silica prism, at the surface of which the beam undergoes total internal reflection (TIR). At the position of TIR, an evanescent field is established whose amplitude decays exponentially with distance from the boundary. This evanescent field can be exploited to investigate interfacial properties and processes such as adsorption and surface reactions, with most applications hitherto focusing on solid/liquid and solid/air interfaces. As highlighted herein, EW-CRDS is particularly powerful for investigations of interfacial processes when combined with other techniques such as basic electrochemical measurements and microfluidic or hydrodynamic techniques. In this tutorial review, the basic elements of EW-CRDS will be introduced and the relative merits of different configurations for EW-CRDS discussed, along with various aspects of instrumentation and design. The type of information which may be obtained using EW-CRDS is illustrated with a focus on recent examples such as molecular adsorption/desorption, deposition/dissolution of nanostructures and interfacial redox reactions. The comparatively new, but complementary, cavity technique of EW-broadband cavity enhanced absorption spectroscopy (EW-BB-CEAS) is also introduced and its advantages compared with EW-CRDS are discussed. Finally, future developments and trends in EW-cavity based spectroscopy are predicted. Notably, the potential for extending the technique to probe other interfaces is exemplified with a discussion of initial interfacial absorbance measurements at a water–air interface.

Patent
08 Jun 2011
TL;DR: In this article, a method for converting light wavelength with emission angle selectivity characteristic is applied to a light source and comprises the following steps: guiding exciting light to emit to a wavelength conversion layer (1) comprising a wavelength converting material so as to excite the excited light; particularly, mounting a medium film/sheet (3) with a smaller refractive index on at least one side of the wavelength conversion layers to reflect back emergent rays with large angles in the wavelength transformation layer by using total reflection phenomena; and mounting an angle selection light-filtering film or sheet (2
Abstract: The invention relates to a method for converting light wavelength with emission angle selectivity characteristic, which is applied to a light source and comprises the following steps: guiding exciting light to emit to a wavelength conversion layer (1) comprising a wavelength conversion material so as to excite the excited light; particularly, mounting a medium film/sheet (3) with a smaller refractive index on at least one side of the wavelength conversion layer (1) to reflect back emergent rays with large angles in the wavelength conversion layer (1) by using total reflection phenomena; and mounting an angle selection light-filtering film/sheet (2) on the light source output side of the wavelength conversion layer (1) to only let out the excited light of which the angle is smaller than a preset emergence angle, and mounting a reflecting film/sheet (5) on the other side Thus, with the method, the fluorescence conversion efficiency of the light source is improved, the light output brightness or the intensity of the light source is improved while the structure of the light source is simplified; and the method has the advantages of low implementation cost and easy implementation

Journal ArticleDOI
TL;DR: The validity of the stationary-phase analysis is demonstrated by numerical simulations of a Gaussian-shaped beam and it is found that the lateral shifts from the negative chiral slab are affected by the angle of incidence and the chirality parameter.
Abstract: The lateral shifts from a slab of lossy chiral metamaterial are predicted for both perpendicular and parallel components of the reflected field, when the transverse electric (TE)-polarized incident wave is applied. By introducing different chirality parameter, the lateral shifts can be large positive or negative near the pseudo-Brewster angle. It is found that the lateral shifts from the negative chiral slab are affected by the angle of incidence and the chirality parameter. In the presence of inevitable loss of the chiral slab, the enhanced lateral shifts will be decreased, and the pseudo-Brewster angle will disappear correspondingly. For the negative chiral slab with loss which is invisible for the right circularly polarized (RCP) wave, we find that the loss of the chiral slab will lead to the fluctuation of the lateral shift with respect to the thickness of the chiral slab. The validity of the stationary-phase analysis is demonstrated by numerical simulations of a Gaussian-shaped beam.

Journal ArticleDOI
TL;DR: In this paper, the excitation of the surface plasmon resonance (SPR) on a gold thin film is discussed within the Kretschmann configuration, where the coupling with the light is achieved by means of a prism in total reflection.
Abstract: The surface plasmon wave is a surface wave confined at the interface between a dielectric and a metal. The excitation of the surface plasmon resonance (SPR) on a gold thin film is discussed within the Kretschmann configuration, where the coupling with the excitation light is achieved by means of a prism in total reflection. The electromagnetic principles are detailed and a simple experimental setup is described that can be used for laboratory experiments for senior students in the third or fourth year of university. This experiment allows accurate determination of the angle of plasmon extinction and discussion of the principles of biosensors based on the SPR. A slight modification of the setup allows the investigation of the dependence of SPR on wavelength and illustrates the damping of SPR due to its coupling with the interband transitions of the gold thin film.

Journal ArticleDOI
TL;DR: In this article, the powder-like orientation of lamellar domains in thin films of the diblock copolymer polystyrene-block-poly(methyl methacrylate) was investigated using grazing-incidence small-angle X-ray scattering (GISAXS) and grazing incidence smallangle neutron scattering(GISANS).
Abstract: The powder-like orientation of lamellar domains in thin films of the diblock copolymer polystyrene-block-poly(methyl methacrylate) is investigated using grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence small-angle neutron scattering (GISANS). Conventional monochromatic GISANS and GISAXS measurements are compared with neutron time-of-flight GISANS. For angles of incidence and exit larger than the critical angle of total external reflection of the polymer, Debye–Scherrer rings are observed. The position of the Debye–Scherrer rings is described quantitatively based on a reduced version of the distorted-wave Born approximation. A strong distortion of the ring shape is caused by refraction and reflections from the film interfaces. Close to the critical angle, the ring shape collapses into a banana shape.

Patent
22 Aug 2011
TL;DR: In this paper, an optical navigation device consisting of an image sensor with an imaging surface; a laser; and an optical waveguide layer having an exposed user surface and a total internal reflection (TIR) surface was presented.
Abstract: The invention provides an optical navigation device comprising: an image sensor with an imaging surface; a laser; and an optical waveguide layer having an exposed user surface and a total internal reflection (TIR) surface on the underside of the exposed user surface. The waveguide layer, laser and image sensor are together arranged to direct radiation emitted by the laser onto the imaging surface at least partly by total internal reflection by the TIR surface.

Journal ArticleDOI
TL;DR: In this paper, an improved approach to amplitude variation with offset (AVO) inversion is proposed based on effective reflection coefficients (ERCs), which generalize plane-wave coefficients for seismic waves generated by point sources and therefore more accurately describe nearcritical and post-critical reflections where head waves are generated.
Abstract: A conventional amplitude variation with offset (AVO) inversion is based on geometrical seismics which exploit plane-wave reflection coefficients to describe the reflection phenomenon. Widely exploited linearizations of plane-wave coefficients are mostly valid at pre-critical offsets for media with almost flat and weak-contrast interfaces. Existing linearizations do not account for the seismic frequency range by ignoring the frequency content of the wavelet, which is a strong assumption. Planewave reflection coefficients do not fully describe the reflection of seismic waves at near-critical and post-critical offsets, because reflected seismic waves are typically generated by point sources. We propose an improved approach to AVO inversion, which is based on effective reflection coefficients (ERCs). ERCs generalize plane-wave coefficients for seismic waves generated by point sources and therefore more accurately describe nearcritical and post-critical reflections where head waves are generated. Moreover, they are frequency-dependent and incorporate the local curvatures of the wavefront and the reflecting interface. In our study, we neglect the effect of interface curvature and demonstrate the advantages of our approach on synthetic data for a simple model with a plane interface separating two isotropic half-spaces. A comparison of the inversion results obtained with our approach and the results from an AVO inversion method based on the exact plane-wave reflection coefficient suggests that our method is superior, in particular for long-offset ranges which extend to and beyond the critical angle. We thus propose that long offsets can be successfully exploited in an AVO inversion under the correct assumption about the reflection coefficient. Such long-offset AVO inversion shows the potential of outperforming a conventional moderate-offset AVO inversion in the accuracy of estimated model parameters.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of high-order diffraction on the absorption and ultimate conversion efficiency of a 1.1 mu m thick Si solar cell with height of 100-800 nm.
Abstract: 1 mu m thick Si solar cells based on nanocone grating (NCG) with height of 100-800 nm and period of 100, 500, and 800 nm are numerically investigated through reflectivities, absorption enhancement factors, absorption spectra, optical generation rates, ultimate efficiencies, and diffraction angles. Compared with the planar Si solar cell, absorption enhancement are observed in any solar cells with NCG surface. Their absorption enhancement mechanism varies with the incident wavelength range. When incident wavelength lambda lambda > 500 nm, even though the absorption enhancement is still dominated by antireflection of the front surface, cavity-resonance effect and guided-mode excitation induced by high order diffraction start to make contribution. When lambda > 600 nm, the contribution of guided-mode excitation induced by lower-order diffraction becomes larger and larger once the diffraction angle is larger than its critical angle. For the structure with P = 100 nm, high-order diffraction cut-off at the longer wavelength range is the main reason of its lower absorption enhancement and ultimate conversion efficiency. For P = 800 nm, the lower absorption enhancement and ultimate efficiency is also observed due to the high reflection loss and mode leakage induced by 1(st) order diffraction where its diffraction angle is lower than its critical angle. Higher absorption and ultimate conversion efficiencies are achieved in P = 500 nm due to the good balance between antireflection performance and guide-mode excitation induced by the high order diffraction is achieved. Moreover, such absorption enhancement is closely related with its height of NCG gratings. Reflection loss reduction, the interaction volume reduction between the incident light and Si material, and higher photon density in NCG structure coexists with H increasing, which results in absorption enhancement in P = 500 nm and P = 800 nm, but absorption reduction in P = 100 nm where high order diffraction cut-off. Based on these analysis, we do believe that high absorption and ultimate conversion efficiency should be achieved in NCG-based solar cells where both the lower reflection in short wavelength domain and guide-mode excitation induced by 1(st) and 2(nd) diffraction in longer wavelength domain can be achieved. According to this rule, the optimized structure is NCG with P = 559 nm and H = 500 nm, by which, the highest optical generation rate of 536.57 x 10(4) W/cm(3) and ultimate efficiency of 28.132% are achieved. Such analysis should benefit the design of the thin film solar cells with nano-structured diffraction gratings.

Journal ArticleDOI
TL;DR: Experiments on the influence of various optical effects on the far-field scattering pattern produced by a cloud of optical bubbles near the critical scattering angle are reported, thought to be fundamental for the development of future works to model these effects and for the extension of the range of applicability of an inverse technique, used to determine the size distribution and composition of bubbly flows.
Abstract: We report experimental investigations on the influence of various optical effects on the far-field scattering pattern produced by a cloud of optical bubbles near the critical scattering angle. Among the effects considered, there is the change of the relative refractive index of the bubbles (gas bubbles or some liquid–liquid droplets), the influence of intensity gradients induced by the laser beam intensity profile and by the spatial filtering of the collection optics, the coherent and multiple scattering effects occurring for densely packed bubbles, and the tilt angle of spheroidal optical bubbles. The results obtained herein are thought to be fundamental for the development of future works to model these effects and for the extension of the range of applicability of an inverse technique (referenced herein as the critical angle refractometry and sizing technique), which is used to determine the size distribution and composition of bubbly flows.

Journal ArticleDOI
TL;DR: In this article, the Dubreil-Jacotin-Long theory was used to interpret the reflection of a short, short, and large-amplitude internal wave train off a steep slope.
Abstract: Remote and in situ field observations documenting the reflection of a normally incident, short, and large-amplitude internal wave train off a steep slope are presented and interpreted with the help of the Dubreil–Jacotin–Long theory. Of the seven remotely observed waves that composed the incoming wave train, five were observed to reflect. It is estimated that the incoming wave train carried Ei = (24 ± 4) × 104 J m−1 to the boundary. The reflection coefficient, defined as the ratio of reflected to incoming wave train energies, is estimated to be R = 0.5 ± 0.2. This is about 0.4 lower than parameterizations in the literature, which are based on reflections of single solitary waves, would suggest. It is also shown that the characteristics of the wave-boundary situation observed in the field are outside the parameter space examined in previous laboratory and numerical experiments on internal solitary wave reflectance. This casts doubts on extrapolating current laboratory-based knowledge to fjord-like...

Journal ArticleDOI
27 May 2011-Pramana
TL;DR: In this article, the reflection of a Hermite-Gaussian beam at an interface between two dielectric media was studied and it was shown that unlike Laguerre-Gaussians, Hermite Gaussians undergo no significant distortion upon reflection.
Abstract: We study the reflection of a Hermite–Gaussian beam at an interface between two dielectric media. We show that unlike Laguerre–Gaussian beams, Hermite–Gaussian beams undergo no significant distortion upon reflection. We report Goos–Hanchen shift for all the spots of a higher-order Hermite–Gaussian beam near the critical angle. The shift is shown to be insignificant away from the critical angle. The calculations are carried out neglecting the longitudinal component along the direction of propagation for a spatially finite, s-polarized, full 3D vector beam. We briefly discuss the difficulties associated with the paraxial approximation pertaining to a vector Gaussian beam.

Journal ArticleDOI
TL;DR: The surface plasmon optical vortex (SPOV) as mentioned in this paper has well defined orbital angular momentum, residing in an azimuthal phase relative to the propagation direction of the internally reflected light.
Abstract: An optical mode is generated in vacuum by the total internal reflection of a beam, at the planar surface of a dielectric on which a metallic film is deposited. When the beam impinging on the surface is a Laguerre–Gaussian (LG) mode, the resulting surface mode with field components in the vacuum region possesses vortex properties, in addition to surface plasmon features. Such surface plasmon optical vortex (SPOV) modes have well-defined orbital angular momentum, residing in an azimuthal phase relative to the propagation direction of the internally reflected light. Significantly, as SPOVs are characterized by a small mode volume, they can strongly couple to atomic or molecular systems in the vicinity of the surface. In particular, SPOVs generated by single or counter-propagating, symmetrically incident laser fields give rise to optical forces that can restrict the lateral in-plane motion of such atoms, thus acting as a trap. Typical atom trajectories, evaluated for sodium atoms initially localized in the vicinity of the metallized surface, exhibit a variety of rotational, vibrational and translational effects, as well as trapping.

Journal ArticleDOI
08 Aug 2011-Analyst
TL;DR: A hybrid technique which uses a scanning X-ray beam to irradiate Gd( 2)O(2)S scintillators and detect the resulting visible luminescence through the tissue to measure optical absorption and detect chemical and physical changes on surfaces embedded in thick tissue is described.
Abstract: We report a high-spatial resolution imaging technique to measure optical absorption and detect chemical and physical changes on surfaces embedded in thick tissue. Developing sensors to measure chemical concentrations on implanted surfaces through tissue is an important challenge for analytical chemistry and biomedical imaging. Tissue scattering dramatically reduces the resolution of optical imaging. In contrast, X-rays provide high spatial resolution imaging through tissue but do not measure chemical concentrations. We describe a hybrid technique which uses a scanning X-ray beam to irradiate Gd2O2S scintillators and detect the resulting visible luminescence through the tissue. The amount of light collected is modulated by optical absorption in close proximity to the luminescence source. By scanning the X-ray beam, and measuring total amount of light collected, one can measure the local absorption near scintillators at a resolution limited by the width of luminescence source (i.e. the width of the X-ray excitation beam). For proof of principle, a rectangular 1.7 mm scanning X-ray beam was used to excite a single layer of 8 μm Gd2O2S particles, and detect the absorption of 5 nm thick silver island film through 10 mm of pork. Lifetime and spectroscopic measurements, as well changing the refractive index of the surroundings indicate that the silver reduces the optical signal through attenuated total internal reflection. The technique was used to image the dissolution of regions of the silver island film which were exposed to 1 mM of H2O2 through 1 cm of pork tissue.

Journal ArticleDOI
TL;DR: Dielectric optical coatings are designed at resonances to reach total absorption, whatever the low value of the imaginary index, and the corresponding field enhancement within the stack can be arbitrarily increased with the optimization procedure.
Abstract: Dielectric optical coatings are designed at resonances to reach total absorption, whatever the low value of the imaginary index. The corresponding field enhancement within the stack can be arbitrarily increased with the optimization procedure. Applications concern optical sensors and threshold lasers.

Journal ArticleDOI
TL;DR: Refracting the k-function of Stavroudis as mentioned in this paper describes a solution of the eikonal equation in a region of constant refractive index, which can be repeated any number of times, and therefore extends the usefulness of the kfunction formalism to multielement optical systems.
Abstract: The k-function of Stavroudis describes a solution of the eikonal equation in a region of constant refractive index. Given the k-function describing the optical field in one region of space, and given a prescribed refractive or reflective boundary, we construct the k-function for the refracted or reflected field. This procedure, which Stavroudis calls refracting the k-function, can be repeated any number of times, and therefore extends the usefulness of the k-function formalism to multielement optical systems. As examples, we present an analytic solution for the k-function, wavefronts, and caustics generated by a biconvex thick lens illuminated by a plane wave propagating parallel to the symmetry axis, and numerical results for off-axis plane-wave illumination of a two-mirror telescope.

Patent
19 Oct 2011
TL;DR: The magnetofluid filling photonic crystal optical fiber F-P magnetic field sensor is characterized in this article, where the sensor probe is formed by fusing a section of hollow photonic laser optical fiber filled with a magnetof-luid and a simple module optical fiber, and the two ends of the optical fiber are respectively stuck by a partial reflection film and a total reflection mirror.
Abstract: The invention discloses a magnetofluid filling photonic crystal optical fiber F-P magnetic field sensor, which belongs to the technical field of optical fiber sensing, and consists of a broadband light source 20, an optical fiber coupler 21 and optical fiber links (31, 32, 33 and 34) of the optical fiber coupler 21, a refractive index matching fluid 22, a sensor probe 23, an electromagnetic coil 18 and a current driving system 19 of the electromagnetic coil, a spectrum analyzer, a computer 24 as well as a connecting cable 26 and a connecting cable 27. The magnetofluid filling photonic crystal optical fiber F-P magnetic field sensor is characterized in that the sensor probe is formed by fusing a section of hollow photonic crystal optical fiber 12 filled with a magnetofluid 13 and a simple module optical fiber 11; the two ends of the hollow photonic crystal optical fiber are respectively stuck by a partial reflection film 14 and a total reflection mirror 15 to form an optical fiber F-P interferometric cavity structure; and the reflection rate of the magnetofluid serving as a medium in the F-P interferometric cavity is changed due to a magnetic field generated by the electromagnetic coil after conducted with a current, thereby causing the change of output spectrums so as to realize magnetic field measurement. The magnetofluid filling photonic crystal optical fiber F-P magnetic field sensor has the advantages of being low in temperature influences, simple in structure, small in size and easy to realize multi-point distribution type sense.