Brewster Incidence Research Articles

Reflection and transmission of an Airy beam in a dielectric slab

The reflection and transmission of a finite-power Airy beam incident on a dielectric slab are investigated by an analytical method. Based on the plane-wave angular spectrum expansion and Fresnel approximation, the analytical expressions of the reflected field, internal field as well as transmitted field in each region are obtained. Through numerical simulations, the intensity distributions of the incident beam, reflected beam, internal beam as well as transmitted beam are presented at oblique incidence. Besides, we also compare the intensity distributions of the geometrical-optics beam field, the first order beam mode field and the actual beam field, which indicates that the contribution of each order beam mode field to the actual beam field is related to the refractive index of the dielectric slab. Meanwhile, the reflection characteristics of the Airy beams in the special cases of Brewster incidence and total reflection are investigated. Finally, the effects of the optical thickness and refractive index of the dielectric slab on the peak intensity distributions and beam shifts of the reflected and transmitted beams are also discussed in detail. The analytical and numerical results will be useful to analyze the propagation dynamics of Airy beam in the dielectric slab and provide some theoretical supports to the design of optical film.

Photonic spin Hall effect by anisotropy-induced polarization gradient in momentum space.

We demonstrate theoretically and experimentally a novel photonic spin Hall effect (PSHE), to the best of our knowledge, at an interface between air and uniaxial crystal, whose optical axis is within the interface plane. Owing to the anisotropy of the crystal, partial cross polarization conversion occurs. For a horizontally polarized paraxial Gaussian beam incidence, a linear polarization gradient forms along the in-plane wavevector in the reflected beam, allowing us to achieve spin separation in real space. The spin separation of the reflected beam can be tuned by rotating the optical axis of the crystal. A maximum spin-dependent displacement up to 0.45 times the incident beam waist is obtained at Brewster incidence. This novel anisotropy-induced PSHE deepens the understanding of spin-orbit interaction and provides a new way for control of spin photons.

Water adsorption on silica and calcium‐boroaluminosilicate glass surfaces—Thickness and hydrogen bonding of water layer

AbstractAdsorption isotherm of water on silica (modeled with fused quartz) and calcium‐boroaluminosilicate (Ca‐BAS) glass surfaces as a function of relative humidity (RH) was studied using Fourier transform infrared (FTIR) spectroscopy. The effective thickness of the adsorbed water layer and the distribution of hydrogen bonding interactions of water molecules in the adsorbed layer were determined by comparing the transmission FTIR spectra collected at the Brewster incidence angle with the theoretically calculated spectra. In the sub‐monolayer regime (<30% RH), differences between the water spectra on fused quartz and Ca‐BAS glass could be related to the areal density of hydroxyl groups as well as the elemental composition of the surface determined with x‐ray photoelectron spectroscopy. In the transition regime (30%–60% RH), multilayers start growing and the difference between the fused quartz and Ca‐BAS surfaces diminishes as the humidity increases. In the multilayer regime (>60% RH), the total amount as well as the hydrogen bonding interactions of adsorbed water layers become insensitive to the surface chemistry and are governed mostly by the phase transition (vapor condensation) behavior. Overall, this study reveals how the water layer thickness and structure on the multicomponent silicate glass surface in ambient conditions are different from those on the pure silica surface.

A Brewster incidence method for shocked dynamic metrology of transparent materials and its error evaluation

The shock etalon method with normal incidence is an effective method to extract the shocked dynamic parameters of transparent materials. In order to eliminate the sample surface reflection, additional efforts on the sample preparation are usually introduced, which may limit the application of the method. Here, we proposed a Brewster incidence method to carry out the shock compression experiment on transparent materials. By utilizing the p-polarized light as the probe pulse at Brewster incidence, the sample surface reflection can be directly eliminated, which consequently simplified the experiment preparations. The errors of the proposed method have been evaluated using a set of virtual experiments. The results show that the shocked dynamic parameters can be accurately and robustly retrieved even when the nominal refractive index of the sample deviates 0.01 from its true value, or the incident angle bias 0.33° from the Brewster angle. Finally, a set of shock compression experiments on a polycarbonate film sample are carried out, and shocked dynamic parameters, such as shock velocity, particle velocity, and shocked refractive index, are successfully measured, for demonstration.

Perfect Brewster transmission through ultrathin perforated films

We address the perfect transmission of a plane acoustic wave at oblique incidence on a perforated, sound penetrable or rigid, film in two-dimensions. It is shown that the Brewster incidence θ∗ realizing so-called extraordinary transmission due to matched impedances varies significantly when the thickness e of the film decreases. For thick films, i.e.ke≫1 with k the incident wavenumber, the classical effective medium model provides an accurate prediction of the Brewster angle independent of e (this Brewster angle is denoted θB). However, for thinner films with ke<1, θ∗ becomes dependent of e and it deviates from θB. To properly describe this shift, an interface model is used (Marigo et al., 2017) which accurately reproduces the spectra of ultrathin to relatively thick perforated films. Depending on the contrasts in the material properties of the film and of the surrounding matrix, decreasing the film thickness can produce an increase or a decrease of θ∗; it can also produce the disappearance of a perfect transmission or to the contrary its appearance.

Variation-free baseline with p-polarized Brewster incidence for infrared measurement of carbon impurities in silicon wafer

In our previous infrared transmission study, the baseline variation [H. Saito and H. Shirai, J. Electrochem. Soc. 147, 1210 (2000)] appeared near the carbon impurity band at 605 cm−1 in the normal incidence infrared spectra of silicon. This occurs because of the diminishing of multiple reflections due to the strong two-phonon absorption in the range of 610–630 cm−1 and the difference in resistivity between the test and reference samples. To solve the problem of baseline variations, p-polarized Brewster incidence has been successfully applied to infrared measurements of carbon impurities in wafer-thick silicon samples. No baseline variations have appeared in this range, owing to the absence of multiple reflections.

Measurement of Giant Spin Splitting of Reflected Gaussian Beams

We investigate theoretically and experimentally the beam shifts of a Gaussian beam reflected by an air-glass interface at Brewster incidence. For a linearly polarized incident beam, the reflected beam will undergo a spatial spin splitting within the plane of incidence. This spin splitting is up to 83 μm when the incident beam waist is 90 μm. Additionally, the reflected beam will be deflected along the direction perpendicular to the incident plane, i.e., undergo an angular shift. The maximum angular shift has been theoretically predicted and experimentally confirmed. Both the spatial spin splitting and angular shift can be controlled by the incident polarization state. These controllable giant beam shifts have potential applications in the design of spin-photonic devices and the optical sensing.

Growth, spectroscopy and lasing of the Yb-doped monoclinic Gd2SiO5 in the prospect of hydrogen laser cooling with Lyman-α radiation

We have grown good optical quality 10% Yb-doped Gd2SiO5 monocrystal by the Czochralski technique. The Yb segregation coefficient was measured to be 0.747. In agreement with the monoclinic symmetry of the host, the Yb fluorescence extrema were found to deviate from the Nm and Ng principal axes and a fourth spectroscopic parameter representing the rotation of the fluorescence distribution was introduced for a full description. Diode pumped laser operation at Brewster incidence was demonstrated to be significantly more efficient if the lasing propagation corresponds to the maximum fluorescence inside the crystal. We obtained a laser emission tunable between 1079 and 1100 nm, showing that our crystal is the best choice for the application to the production of QCW Lyman-α radiation by resonant four-wave-mixing in mercury vapor.

Measurements of phosphorus and boron concentrations in Czochralski silicon wafer-thick samples by p-polarized Brewster incidence far-infrared transmission

Determination of phosphorus and boron concentrations in Czochralski-grown silicon wafer-thick samples has been examined by means of low-temperature high-resolution far-infrared transmission measurements with p-polarized light incident at Brewster angle. The measurements were taken at about 8.7 K with a spectral resolution of 0.5 cm−1 under halogen light illumination. Linear correlations are clearly obtained between the absorption coefficients of several phosphorus and boron transitions and their concentrations, which are approximately in the range of 7.7 × 1013–1.6 × 1015 atoms cm−3 for phosphorus and of 2.5 × 1014–7.6 × 1014 atoms cm−3 for boron. The correlations are obtained regardless of the surface processing conditions of the samples. These are because interference fringes due to internal multiple reflections in wafer-thick silicon samples are almost suppressed using this incidence. The detection limit of phosphorus is about 1.2 × 1013 atoms cm−3 and that of boron is about 4.2 × 1013 atoms cm−3. P-polarized Brewster angle incidence has made it possible to determine phosphorus and boron concentrations in wafer-thick samples.

Eigenpolarizations for giant transverse optical beam shifts.

We show how careful control of the incident polarization of a light beam close to the Brewster angle gives a giant transverse spatial shift on reflection. This resolves the long-standing puzzle of why such beam shifts transverse to the incident plane (Imbert-Fedorov shifts) tend to be an order of magnitude smaller than the related Goos-Hänchen shifts in the longitudinal direction, which are largest close to critical incidence. We demonstrate that with the proper initial polarization the transverse displacements can be equally large, which we confirm experimentally near Brewster incidence. In contrast to the established understanding, these polarizations are elliptical and angle dependent. We explain the magnitude of the Imbert-Fedorov shift by an analogous change of the symmetry properties for the reflection operators as compared to the Goos-Hänchen shift.

Cross polarization effects of vortex beam in reflection

Based on the angular spectrum theory, we establish a propagation model for vortex beam in reflection at an air-glass interface in the paraxial approximation, and investigate the cross polarization effects. When the horizontal polarization vortex beam is incident at different angles, the cross polarization component of the reflected beam shows a double-peak intensity distribution which is similar to the first-order Hermite-Gaussian mode. The distribution of horizontal polarization component is similar to that of the incident beam, and will show a double-peak intensity distribution which is perpendicular to the distribution of cross polarization components at the Brewster incidence. For the incident beam with arbitrary linear polarizations, we find that the polarized direction of cross polarization component is not perpendicular to the incident polarized direction, but exhibits an interesting rotational characteristic. The physical nature of this phenomenon is attributed to the different reflection coefficients of parallel and perpendicular polarizations. Experimental results agree well with our theoretical analysis.

Material Survey for a Novel Beam Splitter Separating High-Order Harmonics from High-Average-Power Fundamental Pulses

We have investigated novel beam splitter (BS) materials to relax thermal issues under irradiation of a high-average-power visible and near infrared (VIS–NIR) laser beam. The material should efficiently reflect a high-order harmonic beam in the extreme ultraviolet (XUV) spectral region and transmit a VIS–NIR fundamental laser beam at a Brewster incidence for the latter beam. We have investigated optical and thermo-mechanical properties of crystalline silicon carbide (SiC), diamond, and rutile since they exhibit high transparency and high index of refraction for a VIS–NIR light. We also address thermal issues of conventional opaque BS materials by measuring their thermal distortion. We have shown that crystalline SiC is the most promising candidate among the other materials because of a high reflectivity for XUV light, as well as an ignorable thermal distortion. The surface flatness of a crystalline SiC plate must be improved to realize an applicable BS in the XUV spectral region.

Demonstration of a quasi-scalar angular Goos-Hänchen effect

We show experimentally that the angular Goos-Hänchen (GH) effect can be easily observed, also without employing its resonant enhancement at Brewster incidence. An s-polarized beam was used to decouple the polarization from the propagation dynamics of the beam. We found that, in this case, the angular GH effect can be strongly enhanced by increasing the angular aperture of the Gaussian beam. Our experiments suggest a route toward observing the angular GH effect for true scalar waves, such as acoustic waves and quantum matter waves.

Brewster cross polarization

We theoretically derive the polarization-resolved intensity distribution of a TM-polarized fundamental Gaussian beam reflected by an air-glass plane interface at Brewster incidence. The reflected beam has both a dominant (TM) and a cross-polarized (TM) component, carried by a TEM(10) and a TEM(01) Hermite-Gaussian spatial mode, respectively. Remarkably, we find that the TE-mode power scales quadratically with the angular spread of the incident beam and is comparable to the TM-mode power. Experimental confirmations of the theoretical results are also presented.

Disappearance of modes in planar Bragg waveguides

We show how the forbidden bands of a Bragg reflector may shrink to points and how some classes of the guided modes of a planar Bragg waveguide may disappear altogether by shrinking with the forbidden bands. We derive the general conditions to determine the missing modes and explain these conditions with examples. It is possible, for example, to design a Bragg waveguide that rejects all antisymmetric modes and supports only symmetric modes for the TE polarization. We also highlight the effect of Brewster incidence on the interpretation of the missing modes for the TM polarization.

Multiscaled polarization effects in Suneve coronata (Lepidoptera) and other insects: application to anti-counterfeiting of banknotes

The scales of many Lepidoptera and the elytra of quite a number of Coleoptera possess specialized micro- and nano-structures that produce special polarization effects. They are constituted by concave multilayered cavities. This leads to two different effects: (1) interferential non-polarized coloration by reflection near normal incidence in the middle of the cavities and (2) polarized interferential colouration at lower wavelength after double reflection near the Brewster incidence at the periphery of the cavities. The macroscopic appearance resembles the “pointillist effect” with one of the component polarized while the other one is not. The first one can be extinguished with linear polarizer so that the colour is modified. In most insects, the structure is locally symmetric; hence, no macroscopic effects can be seen. In certain species, this symmetry is partly broken, and a slight effect can be observed. In the wing dorsal surface of the fascinating neotropical butterflies genus Suneve, perpendicular structures of two different kinds in size polarize the reflected light. The larger one is constituted by the convex cover scales whose apex falls perpendicularly on the bases of the following scales, creating long polarized valley (50 μm width) transversally running across the wing. The smaller one is constituted by the ridges of the scales (2 μm apart) that polarize light in the perpendicular direction. Adapted multilayered structures can be deposited onto banknotes to create anti-counterfeiting patterns as a further development of protection and security. Different effects can be produced by the use of such structures. (1) Changes of luminosity: A specific pattern will be constituted by two different areas: one with horizontal concave multilayered structures, and the other one with vertical structures. Under unpolarized light, the reflected spectra of these different areas are identical and no pattern appears. Under polarized light, i.e., through a linear polarizer, one or the other area is partly extinguished, according to the orientation of the polarizer, and the pattern appears. (2) Changes in colours: a compound colour can be produced by the juxtaposition of planed and grooved surfaces. Due to the change of incidence of the incoming light, the colours of these two zones are different, but that produced by the first one is unpolarized while the second one is partly polarized and can be modified with a linear polarizer.

Demonstration of an optical polarization magnifier with low birefringence

In any polarimetric measurement technique, enhancing the laser polarization change of a laser beam before it reaches the analyzer can help in improving the sensitivity. Enhancement of a small polarization rotation can be performed using an optical component having a large linear dichroism, the enhancement factor being equal to the square root of the ratio of the two transmission factors. A pile of parallel plates at Brewster incidence seems appropriate for realizing such a polarization magnifier. In this article, we address the problem raised by the interference in the plates and between the plates, which affects the measurement by giving rise to birefringence. We demonstrate that wedged plates provide a convenient and efficient way to avoid this interference. We have implemented and characterized devices with four and six wedged plates at Brewster incidence, which have led to a decisive improvement of the signal-to-noise ratio in our ongoing parity violation measurement.

Brewster-angled chirped mirrors for high-fidelity dispersion compensation and bandwidths exceeding one optical octave

A novel design approach for dispersion-compensating chirped mirrors with greater-than-octave bandwidth is proposed. The commonly encountered problem of dispersion ripple is overcome by impedance matching via Brewster incidence in respect to the top-layer coating material. This approach totally suppresses undesired reflections off the interface to the ambient medium without any need for complicated matching sections. It is shown that Brewster-angled chirped mirrors can deliver ultrabroadband dispersion compensation over a much wider bandwidth than conventional doublechirped mirrors and without the mechanical complexity of back-deposition approaches. Due to their relatively simple structure, the sensitivity of the dispersion of the Brewster-angled designs towards growth errors is greatly reduced. Therefore, this new generation of chirped mirrors appears ideal for compression of continuum pulses with a potential of pulse durations in the single-cycle regime.

A Numerical Study of TM-Type Surface Waves on a Grounded Dielectric Slab Covered by a Doubly Periodic Array of Metallic Patches

In this paper we numerically study the propagation of surface waves guided by a metal-backed dielectric slab with biperiodic metallizations on its surface. Such structures are electromagnetic absorbing screens when the dielectric slab is lossy. In this paper, the surface waves are characterized by their longitudinal and transverse wave numbers, which are deduced from the complex pole locations of the reflection coefficient of the screens. The reflection coefficients can be obtained with a moment method. These reflection coefficients are generalized to complex incident wave numbers. The poles are isolated in the complex plane with the help of the argument principle and are calculated with a numerical method based on Muller's algorithm. Then the parametric study of the wave numbers of the surface waves shows that the absorption of an electromagnetic wave by the screens at normal incidence is due to a resonance of the real part of the transverse wave number of the excited surface wave. We also show that there exists a Brewster incidence angle for the absorbing screens with suitable metallization array dimensions. This Brewster angle appears when the pole crosses the branch cut of the two-sheeted Riemann space of the reflection coefficient.

A NUMERICAL STUDY OF TM-TYPE SURFACE WAVES ON A GROUNDED DIELECTRIC SLAB COVERED BY A DOUBLY PERIODIC ARRAY OF METALLIC PATCHES - Abstract

In this paper we numerically study the propagation of surface waves guided by a metal-backed dielectric slab with biperiodic metallizations on its surface. Such structures are electromagnetic absorbing screens when the dielectric slab is lossy. In this paper, the surface waves are characterized by their longitudinal and transverse wave numbers, which are deduced from the complex pole locations of the reflection coefficient of the screens. The reflection coefficients can be obtained with a moment method. These reflection coefficients are generalized to complex incident wave numbers. The poles are isolated in the complex plane with the help of the argument principle and are calculated with a numerical method based on Müller's algorithm. Then the parametric study of the wave numbers of the surface waves shows that the absorption of an electromagnetic wave by the screens at normal incidence is due to a resonance of the real part of the transverse wave number of the excited surface wave. We also show that there exists a Brewster incidence angle for the absorbing screens with suitable metallization array dimensions. This Brewster angle appears when the pole crosses the branch cut of the two-sheeted Riemann space of the reflection coefficient.