Optical third-harmonic generation in coupled microcavities based on porous silicon

The resonance features of the third-harmonic generation have been observed in 1D coupled microcavities consisting of three Bragg reflectors and two identical half-wave layers of mesoporous silicon. The third-harmonic intensity increases by a factor of about 10³ in the resonance of fundamental radiation with each of the modes of coupled microcavities. It has been shown that the resonance positions in the angular spectra of the third-harmonic intensity depend on the coupling between microcavities that is determined by the transmission of the intermediate Bragg reflector. In the framework of the transfer-matrix method with nonlinear sources, it has been shown that the basic mechanism of the enhancement of the third-harmonic generation in coupled microcavities based on porous silicon is the constructive interference of the partial third-harmonic waves that are generated by near-surface layers.     

Crystal and molecular structures of the complexes of cobalt dichloride with 1-isopropenylimidazole and 1-vinylimidazole

The crystal and molecular structures of bis(1-isopropenylimidazole)dichlorocobalt (C₁₂H₁₆Cl₂·N₄Co) [R 0.036 (R _W 0.089) for 3229 unique reflections with I > 2σ(I)] and tetra(1-vinylimidazole)dichlorocobalt (C₂₀H₂₄Cl₂N₈Co) [R 0.031 (R _W 0.072) for 1863 unique reflections with I > 2σ(I)] were determined. In these molecular complexes, the monodentate terminal 1-alkenylimidazole ligands coordinate to the metal via a “pyridine” nitrogen atom. In C₁₂H₁₆Cl₂N₄Co, the Co atom has a distorted tetrahedral 2N,2Cl coordination. The coordination polyhedron of cobalt in C₂₀H₂₄Cl₂N₈Co is a strongly elongated 4N,2Cl octahedron. The Co-N and Co-Cl bonds [Co-N 2.015(2) and 2.032(4) Å; Co-Cl 2.229(2) Å] in the tetrahedral complex C₁₂H₁₆Cl₂N₄Co are shorter than those in the octahedral complex C₂₀H₂₄Cl₂N₈Co [Co-N 2.134(2) and 2.157(2) Å; Co-Cl 2.518(1) Å]. In the structures of both complexes there are short contacts involving the Cl atoms.     

Extraction of Aromatic Hydrocarbons from Hydrofined Diesel Fraction with 2-Methoxyethanol in the Presence of Pentane

Five-step countercurrent extraction of aromatic hydrocarbons from hydrofined diesel fraction with the 2-methoxyethanol-water-pentane extraction system was studied. The process was performed on a rotary-disk extractor.     

MOLECULAR STRUCTURES AND CRYSTAL PACKINGS OF STYRYLDIAZINES

Journal of Structural Chemistry - Crystal structures of three isomeric styryldiazine derivatives (E)-2-(3,4-dimetoxystryl)pyrazine, (E)-2-(3,4-dimetoxystryl)pyrimidine, and...     

Spatial Separation of Scalar Light Beams with Orbital Angular Momentum Using a Phase Metasurface

JETP Letters - The concept and design optimization of a polarization-independent dielectric metasurface for the spatial separation of scalar light beams with different values of the orbital angular...     

Bound States in the Continuum in Magnetophotonic Metasurfaces

JETP Letters - We analyze the enhancement mechanisms of magneto-optical effects in all-dielectric metasurfaces caused by the bound state in the continuum resonance. In a structure under study, a...     

Particlelike excitations in the polypeptide chain model

The α-helical protein molecule is modeled by a one-dimensional crystal chain with three peptide groups in the lattice cell and with the nearest and third neighbor interactions. Three types of solitonlike solutions describing excitation motion along the model have been obtained. The first one is three modulated waves which are in phase. The other two are modulated waves with phase shifts equal to ?π and \documentclass{article}\pagestyle{empty}\begin{document}$ {\textstyle{4 \over 3}} $\end{document}π, respectively.     

One-dimensional anisotropic magnet in the long-wavelength approximation

The nonlinear equation for the wavefunction of spin excitations in the long-wavelength approximation possessing a soliton-like solution is obtained by means of an exact transition from Pauli operators to Fermi operators.     

Role of optical interference effects in the enhancement of magnetization-induced second-harmonic generation

Received: 14 October 1998     

Femtosecond relaxation dynamics of surface plasmon-polaritons in the vicinity of fano-type resonance

Temporal modification of femtosecond laser pulses reflected from planar periodic metal nanostructures with resonant excitation of surface plasmon-polaritons is experimentally studied. Spectral time-resolved measurements of the second-order cross-correlation function performed with the pulse duration comparable with the surface plasmon-polariton relaxation time (about 100 fs) show the strong spectral dependence of the envelope of the reflected femtosecond pulse described by Fano-resonance parameters.