Journal des lasers, optiques et photoniques

We present a scheme for conversion of pulsed light from 1.06 to 2.1 μm using a periodically poled ferroelectric crystal within a resonant cavity in which Optical Parametric Generation (OPG) nonlinear optical process occur when pumped with a pulsed Nd:YAG laser. This device emits 9 ns pulses of over 300 μJ and is a viable source for use with PhS-OCT system for generation of shear waves in a soft medium.

A light yellow colored bentonite clay mineral obtained from India is studied. X ray diffraction (XRD) studies are suggesting that Fe₂O₃, Al₂O₃, quartz and Ca bentonite phases are present in the compound. Ca-bentonite is the major constituent and its unit cell is monoclinic with a=5.16, b=8.798, c=9.347Å and β=100.46°. Internal structure studied using Transimission electron microscope (TEM) suggests that the clay consists of iron oxide, aluminium oxide, quartz, Ca bentonite. Tetrahedral and octahedral layers are present. Fe³⁺ is present in the location of Al³⁺ in the unit cell of Ca-bentonite. Electron paramagnetic resonance (EPR) results indicate that the unit cell of the crystal contains Fe(III), and its g values are found to be 4.19 and 2.13. IR studies are indicating that the presence of silicate and hydroxyl anions as ligands. Nonlinear optical measurements are indicating that the compound is having good potential applications in laser safety devices.

We present in this paper the special structure of photonic crystal fiber (PCF), the temperature-dependent Yb³⁺ photonic crystal fiber lasers model with stimulated Brillouin scattering (SBS) is presented by solving the steady-state rate equations with the (SBS) in the linear cavity. The numerical results show that the pump power, laser power and stokes powers propagating along axial positions are obtained by using the finite difference method and shooting method. The comparison results of the photonic crystal fiber laser model without temperature factor, the output powers and the SBS threshold powers in different pump schemes are obtained in the simulation paragraph. The numerical results show that the SBS threshold power in the two-end pump scheme is more noticeable than other pumps schemes.

It’s well known that the optical retardation measurement depends directly on the birefringence of the liquid crystal. We are interested by the simplest distorted texture of discotic columnar liquid crystals (DCLC) where the columns curve circularly their structures around the core line. The present opportunity is to use a hexagonal columnar structure where the topology of columns hemispheres is well known. We have observed the DCLC interference fringes from a half drop in the hexa-n-hexyloxytriphenylene close to the isotropic transition. Using polychromatic spectral lamp, the optical retardation symmetry has been used to describe the spherical texture of the columns. The present work shows that the optical retardation exhibits a noticeable difference between the birefringence measurement Δn versus the wavelength λ. The birefringence is given by the relationship: , (Δno=-0,196 and B=0,023 μm2).

A technique that could be used for sensing organic compounds is presented. In ethanol, Rhodamine-6G (a laser dye) was dissolved to obtain a Rhodamine-ethanol (Rh-Eth) solution with the concentration of Rhodamine-6G being 0.005 M. Methanol (0.25 cm3) was added to the Rh-Eth solution and the Rh-Eth-Me solution so obtained was pumped with a nitrogen laser. A blue shift in the fluorescence spectrum of the Rh-Eth-Me was observed as compared to the Rh-Eth solution without methanol. A similar blue shift was observed in the Rh-Eth solution when acetone and acetonitrile were separately added. When Rhodamine-6G and Coumarin460 were added with Polymethyl methacrylate (PMMA) in ethanol, a blue shift was observed in the fluorescence spectrum as compared to the Rh-6G and Cou460 in ethanol without PMMA. The phenomena of spectral shifts in the fluorescence spectrum can be used to sense organic compounds and a mechanism is discussed.

Main centers for the development of applied plasmonics in Ukraine are Institute of Cybernetics and Lashkaryov Institute of Semiconductor Physics. The most significant advantage of biosensors “Plasmon” series produced by Lashkaryov Institute of Semiconductor Physics are block-modular design, which makes it easy to update the device for various applications and possibility investigation gaseous media. Original technical solutions allowed making quite inexpensive and affordable analytical device for researches in Ukraine, yet comparable in detection limit (3 × 10-6 RIU) and accuracy (± 1 × 10-6 RIU) with the most applicable instruments from the world’s leading manufacturers. Wide measuring range from 1,0 to 1,5 RIU allowed study liquids with high refractive index like motor oils and polymers. So, promising areas of development of SPR-devices are increasing their accuracy, improving the technology of manufacturing a sensitive element and developing algorithms for processing results. This makes it possible to expand the use of SPR in medicine, microbiology and industry.

We study electromagnetic excitations in non-ideal 1D microcavity lattice with the use of the virtual crystal approximation. The effect of elastic deformation on the excitation spectrum of a microcavity chain is numerically modeled for 1D non-ideal microcavity supercrystal containing quantum dots and without them. The adopted approach helps us obtain the dispersion dependence of collective excitation frequencies and the energy. The analytical expressions for polaritonic frequencies, effective mass and group velocities as functions of corresponding quantum dots and vacancies concentrations are obtained.