Fano Enhancement of Unlocalized Nonlinear Optical Processes

Field localization boosts nonlinear optical processes at the hot spots of metal nanostructures. Fano resonances can further enhance these "local" processes taking place at the hot spots. However, in conventional nonlinear materials, the frequency conversion takes place along the entire crystal body. That is, the conversion process is "unlocalized". The path interference (Fano resonance) schemes developed for localized processes become useless in such materials. Here, we develop Fano enhancement schemes for unlocalized nonlinear optical processes. We show that 3 orders of magnitude Fano enhancement multiply the enhancements achieved via field trapping techniques, e.g., in epsilon-near-zero~(ENZ) materials. We demonstrate the phenomenon both analytically and by numerical solutions of Maxwell's equations. The match between the two solutions is impressive. We observe that the interference scheme for unlocalized processes is richer than the one for the local processes. The method can be employed for any kind of nonlinear optical conversion. Moreover, the Fano enhancement can be continuously controlled by an applied voltage.Comment: 10 pages, 5 figure

The electronic and optical properties of MB12 (M = Zr, Hf, Y, Lu) dodecaboride compounds

We have presented the results of ab initio investigations on the structural, electronic and optical properties of MB12 (M = Zr, Hf, Y, Lu) dodecaboride compounds. Especially, the lattice parameters, bond distances, bulk modulus, electronic band structure, density of state, optical properties and their related quantities such as dielectric constants, refraction index and energy-loss function are calculated, and it is shown that the compounds have a metallic character and a large static dielectric constant. Our structural results are in agreement with the available experimental and other theoretical data

Structural, electronic, elastic and optical properties of CdxZn1-xTe mixed crystals

WOS: 000264779900019PubMed: 21825421The structural, electronic, elastic and optical properties of CdxZn1-xTe ternary mixed crystals are investigated by the first-principles plane-wave pseudopotential method within the LDA approximations. Basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (C-ij) and the electronic band structures, are calculated. We also predict the shear modulus, Young's modulus and Poisson's ratio. Moreover, we have calculated the optical properties (dielectric functions, refractive index, extinction coefficient and energy loss function) of these ternary mixed crystals. Our results agree well with the available data in the literature.Gazi University Research-Project Unit [05/2008-42]This work is supported by Gazi University Research-Project Unit under project no. 05/2008-42

The elastic and mechanical properties of MB12 (M = Zr, Hf, Y, Lu) as a function of pressure

WOS: 000311503000024By means of plane-wave density functional first-principles calculations within the generalized gradient approximation (GGA), we report the structural, elastic and mechanical properties of MB12 (M = Zr, Hf, Y, Lu) with UB12-type structure. The lattice constants, bulk modulus, elastic constants and related quantities such as Young's modulus, shear modulus, Zener anisotropy factor, Poisson's ratio and Cauchy pressure are calculated and compared with the available experimental and other theoretical data. A deeper understanding, the pressure variations of the lattice constants, bulk modulus, elastic constants and other mechanical properties are also analyzed in a wide pressure range (0-50 GPa) and their trends are discussed. Additionally, Mulliken population analysis is used to clarify the bonding nature of all compounds. Combining the bonding nature and the structural information, microhardnesses of all compounds are calculated theoretically and then the detailed comparisons between hardness and other mechanical properties such as bulk modulus and shear modulus are made. (C) 2012 Elsevier B.V. All rights reserved.Turkish Prime Ministry State Planning Agency [2011K120290]This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2011K120290

First-principles study on the MAX phases Tin+1GaNn (n=1,2, and 3)

WOS: 000378873900059We have performed first-principles density functional theory calculations within generalized-gradient approximation to obtain the structural, mechanical, electronic, and dynamic properties of Tin+1GaNn compounds. In order to examine the stability of these compounds, formation enthalpies, single-crystal elastic constants, and phonon dispersion curves were calculated. We show that all compounds are stable, while alpha-Ti4GaN3 is the most stable. The density of states calculations also demonstrate that all of the compounds are metallic. Additionally, bonding nature and related characteristics such as Mulliken atomic charges and bond overlap populations were investigated. Furthermore, thermodynamic properties were calculated by means of phonon dispersion curves. The results are compared in this work with available experimental values and theoretical calculations.State Planning Organization of Turkey [2011K120290]This work was partly supported by the State Planning Organization of Turkey under Grant No. 2011K120290. Some of the calculations were performed in the high performance computing center (HPCC) at Gazi University

First-principles study of structural, elastic, lattice dynamical and thermodynamical properties of GdX (X = Bi, Sb)

WOS: 000277675400001The results are presented of first-principles calculations of the structural, elastic and lattice dynamical properties of GdX (X = Bi, Sb). In particular, the lattice parameters, bulk modulus, phonon dispersion curves, elastic constants and their related quantities, such as Young's modulus, Shear modulus, Zener anisotropy factor, Poisson's ratio, Kleinman parameter, and longitudinal, transverse and average sound velocities, were calculated and compared with available experimental and other theoretical data. The temperature and pressure variations of the volume, bulk modulus, thermal expansion coefficient, heat capacities, Gruneisen parameter and Debye temperatures were predicted in wide pressure (0-50 GPa) and temperature ranges (0-500 K). The plane-wave pseudopotential approach to the density-functional theory within the GGA approximation implemented in VASP (Vienna ab initio simulation package) was used in all computations.Turkish Prime Ministry State Planning Agency [2001K120590]This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2001K120590 and we kindly acknowledge Prof. Dr Suleyman Ozcelik for his financial support

The structural, electronic and optical properties of CdxZn1-xSe ternary alloys

WOS: 000288043700027The structural, electronic, and optical properties of CdxZn1-xSe alloys are investigated using the first-principles plane-wave pseudopotential method within the LDA approximations. In particular, the lattice constant, bulk modulus, electronic band structures, density of state, and optical properties such as dielectric functions, refractive index, extinction coefficient and energy loss function are calculated and discussed. Our results agree well with the available data in the literature.Turkish Prime Ministry State Planning Agency [2001K120590]This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2001K120590

Electronic, elastic and optical properties on the Zn1-xMgxSe mixed alloys

WOS: 000286112900018The structural, elastic, electronic and optical properties of Zn1-xMgxSe ternary mixed crystals are investigated by utilizing the first-principles plane-wave pseudopotential method within the LDA approximations. Some basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (C-ij), Shear modulus, Young's modulus, Poison's ratio, Lame constants and the electronic band structures, are calculated. We have, also, predicted the optical properties such as dielectric functions, refractive index and energy loss function of these ternary mixed crystals. Our results agree well with the available data in the literature.Gazi University [05/2008-42]This work is supported by Gazi University Research-Project Unit under Project No: 05/2008-42

Electronic, elastic and optical properties on the Zn1-xMgxSe mixed alloys

The structural, elastic, electronic and optical properties of Zn1-xMgxSe ternary mixed crystals are investigated by utilizing the first-principles plane-wave pseudopotential method within the LDA approximations. Some basic physical properties, such as lattice constant, bulk modulus, second-order elastic constants (C-ij), Shear modulus, Young's modulus, Poison's ratio, Lame constants and the electronic band structures, are calculated. We have, also, predicted the optical properties such as dielectric functions, refractive index and energy loss function of these ternary mixed crystals. Our results agree well with the available data in the literature

The electronic and optical properties of Zn1-xCaxSe mixed alloys

WOS: 000279899900035We have investigated the structural, electronic, and optical properties of Zn1-xCaxSe ternary alloys using first principles calculations within the plane-wave pseudopotential method. Some basic physical properties, such as lattice constant, bulk modulus, electronic band structures, and optical properties (dielectric functions, refractive index, and energy loss function) were calculated. In addition, the effects of composition x on bulk modulus, band gap, refractive index and dielectric function were calculated. Our results agree well with the available data in the literature. (C) 2010 Elsevier Ltd. All rights reserved.Turkish Prime Ministry State Planning Agency [2001K120590]This work was supported by the Turkish Prime Ministry State Planning Agency under Projects No. 2001K120590