Optical Dimensional Phenomena in Thin Layers of Gold and Atomic Semiconductors

We have investigated optical dimensional phenomena which are manifested as the thickness dependences of the indices of refraction n and absorption k and of the magnitude of the quasiBrewster angle of thin layers of gold. In the range of thicknesses 20 < d > 180 , all these phenomena have an oscillating character. Based on the earlier published experimental data on the energy coefficients of transmission T and reflection R of thin layers of atomic semiconductors (Se, Te, Ge, and Si), new calculations of the thickness dependences of n and k have been carried out without the simplifying assumptions which lead to incorrect results. The errors in determining the optical constants of thin layers from photometric data have been analyzed in detail. The causes of the earlier errors in works devoted to this kind of investigation have been established.     

Collinear Acousto–Optic Interaction of Light Beams near the Optical Axes of Biaxial Crystals

Collinear acousto–optic interaction of light beams near the optical axes of biaxial crystals, including gyrotropic ones, is considered. Efficient acousto–optic transformation of fast and slow light beams under the conditions of internal conical refraction has been revealed. It is shown that the width of the transmission band and the central frequency of ultrasound in collinear acousto–optic filtration in a nongyrotropic crystal are determined by the angle at the apex of the cone of wave vectors (by the anisotropy of the crystal) and in a gyrotropic one by the projection of the gyration vector onto the direction of the optical axis.     

溶液折射率公式的一种验证方法

给出了通过阿贝折射仪测溶液折射率和百分比浓度来验证其折射率公式的一种方法。     

Confocal Raman Microspectroscopy: Calculation of Corrected Depth Profiles of Wet‐Chemically Modified Polymer Films

Summary: A mathematical approach developed to correct depth profiles of wet‐chemically modified polymer films obtained by confocal Raman microscopy is presented which takes into account scattered contributions originated from a diffraction‐limited laser focal volume and the refractive index of the sample. The method is demonstrated in both virtual and real samples where it is shown that considerable differences between apparent and corrected depth profiles exist at the surface, especially when profiles with strong concentration gradients are dealt with or an instrument with poor depth resolution is used.

Comparison of depth profiles obtained by simple normalization (solid line) and normalization after correction of the data with respect to diffraction effects.     

Confocal Raman microscopy: how to correct depth profiles considering diffraction and refraction effects

A new approach to obtain corrected depth profiles by confocal Raman microscopy, which considers diffraction and refraction effects is presented. The problem of diffraction effects encountered intrinsically in the confocal configuration can be described using a linear Fredholm integral equation of the first kind, which correlates apparent and true Raman intensities with the depth resolution curve of the instrument. Refractive index differences between air and the polymer sample, which cause further errors in the obtained depth profile due to strong aberration effects have been considered. This has been carried out using an empirical variation of the depth resolution function, which is able to simulate the broadening of the depth of focus with depth and also the discrepancy between nominal and measured depth scales. It is shown that considerable differences between apparent and corrected depth profiles exist at the surface and that these depend on the gradient of the profile and the depth resolution of the Raman microscope. Copyright © 2007 John Wiley & Sons, Ltd.     

Existing conditions of full bandgaps and absolute negative refraction in metallic-dielectric photonic crystal

This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic-dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10{\%} is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.     

Structure and properties of electromagnetic metamaterials

Metamaterials are artificial materials structured on a subwavelength scale to provide electromagnetic properties beyond those available in nature. Progress in this young field has been startlingly swift. The last year alone has seen the realization of the first optical negative‐index metamaterials and the constructon of two very striking metamaterial‐based devices: an invisibility cloak and a far‐field lens capable of subwavelength imaging. Here, I review these developments and the key concepts that made them possible.     

Spectrum of Radiation Transmission by a Thin Layer of Resonant Atoms

We have explored the possibility of observing bistability of the frequency dependence of transmission of a thin (less than the wavelength of the acting laser radiation) surface layer of active atoms. For the external field strength corresponding to the transition saturation, we predict the hysteresis behavior of transmission on separate portions of the dependence and sharp asymmetry of resonance curves of absorption if the influence on the dielectric constant of the medium of a layer of transitions adjacent to the resonance one and capable of interacting with radiation is taken into account.     

Control the polarization state of light with symmetry-broken metallic metastructures

Controlling the polarization state, the transmission direction, the amplitude and the phase of light in a very limited space is essential for the development of on-chip photonics. Over the past decades, numerous sub-wavelength metallic microstructures have been proposed and fabricated to fulfill these demands. In this article, we review our efforts in achieving negative refractive index, controlling the polarization state, and tuning the amplitude of light with two-dimensional (2D) and three-dimensional (3D) microstructures. We designed an assembly of stacked metallic U-shaped resonators that allow achieving negative refraction for pure magnetic and electric responses respectively at the same frequency by selecting the polarization of incident light. Based on this, we tune the permittivity and permeability of the structure, and achieve negative refractive index. Further, by control the excitation and radiation of surface electric current on a number of 2D and 3D asymmetric metallic metastructures, we are able to control the polarization state of light. It is also demonstrated that with a stereostructured metal film, the whole metal surfaces can be used to construct either polarization-sensitive or polarization-insensitive prefect absorbers, with the advantage of efficient heat dissipation and electric conductivity. Our practice shows that metamaterials, including metasurface, indeed help to master light in nanoscale, and are promising in the development of new generation of photonics.     

Blue light emission and amplification in left-handed isotropic Metallo-Semiconductor Photonic Crystal

A new left-handed isotropic design of semiconductor Photonic Crystal with plasmonic (Aluminum) nanorod inclusion is analyzed and proposed to demonstrate All-Angle Negative Refraction (AANR) with blue light amplification. It is shown that the proposed structure provides negative real values of both permeability (μ) and permittivity (?) with extremely low imaginary values for visible light. Phase slope and phase velocity is shown to be negative for blue light for proposed left-handed structure. Index matched to the incident medium and compensated losses due the gain assistance lead the light amplification in the designed structure. Finite Difference Time Domain (FDTD) method is applied to study left-handed transmission and reflection properties. Extremely high Left-Handed Transmission Efficiency is calculated which is found to be more than 99% for the proposed structure. Fabrication tolerance with effect of change in plasmonic nanorod radius by ±10% is also analyzed. Further, left-handed transmission for blue light is confirmed by analyzing the far-field spectrums of the proposed structure obtained by employing 3D FDTD method. Demonstration and study of near-field and far-field resonance reveals the nano-photonic application potential of the proposed structure as directional optical nano-antenna, polarizer and filter.