Ultrashort pulse generation in the medium with induced optical anisotropy

Abilities of the method of accumulation of coherent unstable response of a medium for amplification of the rotated component of the probe wave’s polarization in the atomic medium of three-level atoms are studied. Probe wave is examined in frames of the perturbation theory and its frequency is considered near to one photon resonance from the ground to the first excited level. The intense monochromatic pump field connects two excited energy levels and propagates through the medium without a change. The broadening of spectral lines caused by the relaxation processes and the Doppler broadening are included into the calculations. It is shown that by multiple consistent instantaneous change of input probe field’s phase from 0 to π and back, it is possible to obtain, in the tail part of the rotated component of the probe field, a separate narrowed light pulse along with the increase in intensity by more than an order of magnitude with respect to the input field.     

Experimental study of magnet undulators with pulsed-wire method

Experimental study of magnetic characteristics of planar magnet undulator for terahertz FEL has been carried out with use of pulsed-wire method. Special attention was given to the procedure of measurement of the second integral of undulator magnetic field, which shows variation of the beam position at passing the undulator magnetic system.     

Sorption behavior of tritiated water on Armenian natural zeolites

Summary The sorptive behavior of tritiated water on natural, irradiated, chemically treated and heated at high temperatures Armenian zeolites was studied and their capacity for the separation and enrichment of tritiated water was evaluated. The distribution coefficients from the batch experiments were calculated for different zeolites and vary between 0.23 and 3.01. The influence of temperature, acidity, basicity, specific activity, electron and gamma-irradiation on sorption has been studied.     

Spectral broadening of a few-cycle laser pulse propagating in fused quartz

Results of theoretical study of nonlinear propagation of a few-cycle laser pulse in a fused quartz are presented. With use of the finite-difference technique we have integrated numerically the system of the nonlinear Maxwell equations describing the propagation of a linearly polarized pulse at the central wavelength in the range of zero dispersion (λ₀ = 1.27 μm) and duration 20 fs. The evolution of the laser pulse spectrum is calculated and the dependences of the shift of the spectral peak on both the strength of electric field and medium length are obtained.     

Synthesis and Anticholinesterase Activity of 4-Arylidene-1-[ω-(dialkylamino)alkyl]-2-phenyl-4,5-dihydro-1(H)-imidazole-5-ones

Russian Journal of General Chemistry - A method for the synthesis of 1-dialkylaminoalkyl-2-phenyl-4-arylidene-5-imidazolones from N-benzoyl-α,β-dehydroamino acid dialkylaminoalkylamides...     

Use of porous silicon for double- and triple-layer antireflection coatings in silicon photovoltaic converters

Reflectance spectrum calculations of double- and triple-layer antireflection coatings made of porous silicon layer are performed, using the optical matrix approach method. Obtained results are compared with the reflectance spectrum of other type antireflection coatings. Lower reflectance value of both double- and triple-layer antireflection coatings made of porous silicon is obtained in comparison to that of SiO₂/TiO₂ antireflection coating. These results can be used in photovoltaic converters.     

Raman-Nath approximation for diffraction of atom in the laser field of counterpropagating waves: Instantaneous switching of interaction

Kapitsa-Dirac scattering problem is solved in Raman-Nath approximation without restrictions on the value of resonance detuning. Formula for the scattering amplitude is obtained in the form of a definite integral. It is shown that in case of Gauss-type superposition initial states the spectrum of scattering has new regularities more needed in atomic optics.     

Approximate solution of the Schrödinger equation for an atom in the field of a standing wave

We present an approximate method of calculation of energy spectrum and wave functions of translational motion of a two-level atom in the field of a standing wave at zero value of the quasimomentum. Wave functions in the momentum representation are expressed in terms of confluent hypergeometric functions in case of continuous spectrum and in terms of Hermitian polynomials in case of discrete spectrum. The energy spectrum exhibits infinite compaction at transition from discrete part to continuous, as it is the case for, e.g., Coulombian potential.     

Increase of probe beam light-induced polarization rotation via accumulation of coherent oscillations

We study possibilities of the method of accumulation of the coherent-nonstationary response of the medium for amplifying the polarization rotation of probe radiation in conditions of a cascade two-photon resonance. The probe field couples the ground level nS _1/2 of an alkali metal atom with the excited doublet nP _1/2,3/2, while the monochromatic pump field couples this doublet with a higher excited state n’S _1/2. We obtain analytic expression for the rotated component of the probe field polarization. It is shown that consistent switching by π the phase of the input probe field may create in the tail portion of its rotated component a separate light pulse with more than an order of magnitude higher intensity, which is a desired result for polarization laser spectroscopy.