Phase-matched four-wave mixing of guided and leaky modes in an optical fiber

Dispersion analysis of guided and leaky modes in an optical fiber shows that these two classes of modes can be coupled to each other through phase-matched four-wave mixing. This process can contribute to the generation of broad and flat supercontinua in highly nonlinear fibers, opening, at the same time, an additional channel of loss through radiation energy transfer from guided to leaky modes.     

Very-large-mode-area photonic bandgap Bragg fiber polarizing in a wide spectral range

A design of a polarizing all-glass Bragg fiber with a microstructure core has been proposed for the first time. This design provides suppression of high-order modes and of one of the polarization states of the fundamental mode. The polarizing fiber was fabricated by a new, simple method based on a combination of the modified chemical vapor deposition (MCVD) process and the rod-in-tube technique. The mode field area has been found to be about 870 μm2 near λ=1064 nm. The polarization extinction ratio better than 13 dB has been observed over a 33% wavelength range (from 1 to 1.4 μm) after propagation in a 1.7 m fiber piece bent to a radius of 70 cm.     

Pluriharmonic Clark measures and analogs of model spaces

Let $B_d$ denote the unit ball of ${\mathbb{C}}^d$, $d\ge 1$. Given an inner function $I:B_d\to B_1$, we study the corresponding family ${\sigma }_{\alpha }[I]$, $\alpha \in ?B_1$, of pluriharmonic Clark measures on the complex sphere. We introduce and investigate related unitary operators $U_{\alpha }$ mapping analogs of model spaces onto $L^2({\sigma }_{\alpha })$, $\alpha \in ?B_1$. In particular, we explicitly characterize the set of $U_{\alpha }^{?}f$ such that $f{\sigma }_{\alpha }$ is a pluriharmonic measure.     

Novel physically adapted STO##‐3G basis sets. Efficiency for prediction of second‐order electric and magnetic properties of aromatic hydrocarbons

Efficient scheme for construction of physically justified STO^##‐3G_el and STO^##‐3G_mag basis sets has been proposed. It is based upon the analysis of analytical form of the first‐order correction functions to unperturbed STO basis sets under the perturbation by electric or magnetic fields. The test calculations of polarizability, magnetic susceptibility and chemical shifts performed for a series of aromatic compounds within the developed basis set in the framework of Hartree‐Fock and Density Functional Theory (DFT) approaches show good agreement of the predicted properties with experiments. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Radiation-initiated telomerization of tetrafluoroethylene in 1,2-dibromotetrafluoroethane

The kinetics of the radiation telomerization of tetrafluoroethylene in 1,2-dibromotetrafluoroethane has been studied. It has been shown that the process occurs very efficiently in the perfluorinated solvent; small doses of γ-radiation (~2 kGy) are required for the complete conversion of the monomer. Telomers with a chain length of 120–360 tetrafluoroethylene units and high thermal stability are formed in the reaction. The structure and properties of the telomers have been studied by IR spectroscopy, thermogravimetry, and elemental analysis.     

Ultrafast three-dimensional submicrometer-resolution readout of coherent optical-phonon oscillations with shaped unamplified laser pulses at 20 MHz

An ultrafast three-dimensional readout of coherent optical-phonon oscillations from a diamond film is demonstrated using temporally and spectrally shaped ultrashort laser pulses, delivered by a compact, oscillator-only laser system. This system integrates a long-cavity ytterbium-fiber-laser-pumped 30?fs Cr:forsterite oscillator with a photonic-crystal-fiber soliton frequency shifter and a periodically poled lithium niobate spectrum compressor, providing coherent Raman excitation and time-delayed interrogation of optical phonons in diamond at a 20?MHz repetition rate with a submicrometer spatial resolution.     

Plasma-assisted coherent backscattering for standoff spectroscopy

We show that an intense coherent backward signal can be generated through a Raman-type four-wave-mixing process using forward propagating fields only. Phase matching for this process is achieved through a plasma modulation of the refractive index. Applications to standoff spectroscopy are discussed.     

New mix-ligand copper(i) and copper(ii) pyrazolate complexes with 2,2′-bipyridine

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