A new mixed birefringent filter

Birefringent filters can be used for tuning lasers, with some advantages over prisms, gratings and tilted etalons. In this paper the transmission characteristics of a new mixed birefringent filter are investigated. The term ‘mixed’ is used because both circular birefringence and linear birefringence have been utilized in the fabrication of this filter.It has a loss-less core, formed by a cascaded system of alternate rotators and retarders, and a linear polarizer at each end. The performance of this filter is better because of the more effective suppression of side peaks. Unlike previous birefringent filters, this one may be used inside a linear resonator.     

Vortex motion in high-Tc films and a micropattern-induced phase transition

A micropattern-induced transition in the mechanism of vortex motion and vortex mobility is observed in high-T_c thin films. The competition between the anomalous Hall effect and the guidance of vortices by rows of microholes (antidots) lead to a sudden change in the direction of vortex motion that is accompanied by a change in the critical current density and microwave losses. The latter effect demonstrates the difference in vortex mobility in different phases of vortex motion in between and within the rows of antidots.     

High mobility W-doped In2O3 thin films: Effect of growth temperature and oxygen pressure on structural, electrical and optical properties

Highly conducting and transparent thin films of tungsten (W)-doped indium oxide were obtained using pulsed laser deposition to study the effect of growth temperature and oxygen pressure on structural, optical and electrical properties. The transparency of the films is seen to largely depend on the growth temperature. The electrical properties, however, are found to depend strongly on both the growth temperature and the oxygen pressure. High mobility (up to 358 cm² V⁻¹ s⁻¹), low resistivity (1.1 × 10⁻⁴ Ω cm), and relatively high transmittance (∼90%) tungsten-doped indium oxide films have been prepared at a growth temperature of 500 °C and an oxygen pressure of 1 × 10⁻⁶ bar.     

Electronic structure and optical properties of CuAlO2 under biaxial strain

An ab initio calculation has been carried out to investigate the biaxial strain ( - 10.71% < ε < 9.13%) effect on elastic, electronic and optical properties of CuAlO(2). All the elastic constants (c(11), c(12), c(13), c(33)) except c(44) decrease (increase) during tensile (compressive) strain. The band gap is found to decrease in the presence of tensile as well as compressive strain. The relative decrease of the band gap is asymmetric with respect to the sign of the strain. Significant differences between the parallel and perpendicular components of the dielectric constant and the optical properties have been observed due to anisotropic crystal structure. It is further noticed that these properties are easily tunable by strain. Importantly, the collective oscillation of the valence electrons has been identified for light polarized perpendicular to the c-axis. From calculations, it is clear that the tensile strain can enhance the hole mobility as well as the transparency of CuAlO(2).     

Fluctuation study of pionisation in ultrarelativistic nucleus-nucleus interaction

The scaled factorial moments and the multifractal moments have been investigated in different??-intervals to study the dynamical fluctuation of pions produced in 200 AGeV³²S-Ag/Br interaction. In order to investigate the detail characteristics of intermittency behaviour, theF-moments are extracted up to the eighth order of moments in differentM-intervals. The analysis indicates a non-thermal phase transition and different regime of particle production during the hadronisation process.     

Seasonal variation of daily total column ozone (TCO) and role of its depletion and formation rate on surface temperature over Dumdum at Kolkata, India

The purpose of the paper is to present the variation of total ozone concentration over Dumdum at Kolkata, India during different seasons. It is concluded that the trend of ozone concentration during different seasons are different. A critical analysis is done and following important results are obtained.

Gold,silver, and palladium nanoparticle/nano-agglomerate generation,collection, and characterization

Generation, collection, and characterization of gold, silver, and palladium nanoparticles and nano-agglomerates (collectively “nanoparticles”) have been explored. The nanoparticles were generated with a spark aerosol generator (Palas GFG-1000). They were collected using a deposition cell under diffusion and thermophoresis. The shapes and sizes of the deposited particles were measured using transmission electron microscopy (TEM). TEM images showed that the particles were in the range of 8–100 nm in diameter, and their shapes varied from nearly spherical to highly non-spherical. Thermophoresis enhanced the deposition of nanoparticles (over the diffusive or the isothermal deposition) in all cases. Further, the size distributions of the nanoparticles generated in the gas phase (aerosol) were measured using a scanning mobility particle sizer (SMPS 3080, TSI) spectrometer. The SMPS results show that an increase in the spark frequency of the generator shifted the size distributions of the nanoparticles to larger diameters, and the total particle mass production rate increased linearly with increase in the spark frequency. The computational fluid dynamics code Fluent (Ansys) was used to model the flow in the deposition cell, and the computed results conform to the observations.