Search

Lead Selenide multilayer thin films were prepared by thermal evaporation technique by successive coatings of Lead and Selenium metals. The temperature of the substrates varied from low to high during the deposition. The optical characterization of the prepared films carried out using UV‐Vis‐NIR spectroscopy and Photoluminescence spectroscopy. The absorption edge towards shorter wavelength (300 nm) may be the quantum size effect at the interfaces of Lead and selenium layers. The films on low substrate temperature have the many linear regions in the optical band gap graph. The calculated band gap is larger than the bulk band gap value of the PbSe material. The room temperature Photoluminescence spectrum was studied under the excitation wavelength of 300 nm. The hot luminescence tail was observed at low temperature substrate. The Effective mass approximation and quantum mechanical models were used to study the quantum size effect of the prepared films and discussed in this paper.

The response of a pressure cell with copper diaphragm of different dimensions for the measurement of pressure using a fused multimode fiber optic coupler is presented. As the pressure varies, the deflection of the diaphragm varies and it modulates the intensity of the reflected light entering into the multimode fused coupler. The sensor is operated in back slope of its characteristic displacement curve and it enabled to sense larger range of pressures. The effect of variation of diameter and thickness of the diaphragm is also studied. The experimental results show that the sensitivity, linearity of the sensor is good and it may finds application in monitoring pressure in industries.

At suitable conditions, sub‐micron sized colloidal particles self assemble into crystalline arrays (known as colloidal crystals) with lattice constants in the visible range. These crystals exhibit Bragg diffraction of visible light, as certain frequencies cannot propagate through, hence can serve as photonic crystals. Highly diffracting photonic crystals (PCs) can be prepared through colloidal route by self‐assembly of monodisperse particles. However size polydispersity (SPD) is inherent to all colloidal suspensions: hard‐sphere, charge stabilized and stimuli responsive microgels. Disorder introduced by temperature and SPD have important implications on optical properties of these crystals. First and second‐type disorder in these crystals are known to arise from thermal motion and SPD, respectively. In the case of photonic crystals prepared through hard‐sphere or charge stabilized suspensions, the SPD should be less than 11% and is not tunable. Thermo‐responsive microgels particles in aqueous medium are k...

The structural, optical and optoelectronic properties of nano structured cadmium sulphide thin films were studied using X‐ray diffraction, optical absorption, photosensitivity and I‐V measurements. Optical studies revealed the band gap of CdS films with particle size ∼26 nm to be around 2.5±0.04 eV. The observed band gap in conjunction with the photosensitivity and n‐type conductivity make them good candidates as the window layers in solar cell applications.

Thin films of Zn0.95Mn0.05O (ZMO) and Al or Bi (1 weight %) incorporated ZMO thin films (viz. Al: Zn0.95Mn0.05O (AZMO) and Bi: Zn0.95Mn0.05O (BZMO)) were grown on Al2O3 substrate by pulsed laser deposition (PLD). X‐ray diffraction studies indicate that all the deposited thin films were highly c‐axis oriented and showed single phase formation with wurtzite structure. Incorporation of 1 wt. % Al leads to reduction of the extensive strain (in AZMO) when compared to the ZMO thin film. However in case of BZMO, compressive strain is observed. Raman studies indicate that the wurtzite structure of the host material is preserved albeit incorporation of 1 wt. % highly mismatched Al or Bi ions. The optical transmission spectra (in the range 350 to 700 nm) of the AZMO and BZMO thin films show significant changes compared to ZMO thin film. The otherwise spin forbidden d‐d transitions of Mn2+ in the tetrahedral symmetry give rise to a strong absorption in the visible region for the ZMO thin film. This absorption band, ...

Monolithic optical sensor with readout electronics are needed in optical communication, medical imaging and scintillator based gamma spectroscopy system. This paper presents the design of three different CMOS photodiode test structures and two readout channels in a commercial CMOS technology catering to the need of nuclear instrumentation. The three photodiode structures each of 1 mm2 with readout electronics are fabricated in 0.35 um, 4 metal, double poly, N‐well CMOS process. These photodiode structures are based on available P‐N junction of standard CMOS process i.e. N‐well/P‐substrate, P+/N‐well/P‐substrate and inter‐digitized P+/N‐well/P‐substrate. The comparisons of typical characteristics among three fabricated photo sensors are reported in terms of spectral sensitivity, dark current and junction capacitance. Among the three photodiode structures N‐well/P‐substrate photodiode shows higher spectral sensitivity compared to the other two photodiode structures. The inter‐digitized P+/N‐well/P‐substrate...

The R9Dy(VO4)7 [R = Sr and Ba] phosphors has been successfully synthesized by high temperature solid state reaction and characterized by XRD as well as photoluminescence measurements. The characteristic of Dy3+ emission was observed in R9Dy(VO4)7 [R = Sr and Ba] phosphors. Photoluminescence (PL) emission results shows the blue and yellow sharp bands at 480 nm and 575 nm for R9Dy(VO4)7 [R = Sr and Ba] phosphor s respectively at the excitation wavelength of 348 nm which is NUV excitation. Thus these phosphors may be applicable for the NUV excited solid state lighting devices as well as white LEDs.

Atmospheric effects can deteriorate the intensity of the received signal and increases the bit error rate (BER). However, the use of error correcting codes in FSO system can mitigate the effect of turbulence and helps in improving the system performance. In this paper, performance of FSO link without and with coding is investigated for coherent (sub‐carrier BPSK and QPSK) and non‐coherent (OOK) modulation schemes. It has been observed that LPDC codes offer considerable performance advantage over convolution codes in terms of coding gain for varying strength of turbulence in the atmosphere. For example, convolution code with viterbi decoding yields coding gain of about 1 dB while LDPC codes shows the improvement of about 4.5 dB at a turbulence level of 0.2 and BER = 10−4 for different modulation schemes.

The Compton scattering measurement on intermetallic alloy Ti3Al is reported in this work. The measurement is made using 59.54 keV gamma‐rays from Am241 source. Theoretical calculation of Compton profile is also performed employing CRYSTAL code within the framework of density functional theory to compare with the measurement. The theoretical profile of the alloy is also synthesized following the superposition model taking the published Compton profiles of elemental solids from the APW method. The experimental study of charge transfer in the alloys has also been done by performing the experimental Compton profile measurements on Ti and Al following the superposition model and charge transfer from Al to Ti is clearly seen on the alloy formation.

Ca3Al2O6:Eu3+ phosphor has been synthesized by combustion method. The phosphors were characterized using X‐ray diffraction and photoluminescence (PL) techniques. The prepared phosphors were excited by 395 nm, the PL emission observed at 616 and 594nm and intensity of 616 nm (5D0→7F2) was almost equal to 594 nm (5D0→7F1). The photoluminescence spectrum of Ca3Al2O6:Eu3+ phosphor showed the emission intensity of phosphor increased with increasing the concentration of europium. The investigated prepared phosphors are suitable for a NUV excited LED.

Transparent ZnO/PMMA (Poly methyl methacrylate) nanocomposites with high‐UV shielding efficiency were reported in this paper. The zinc oxide (ZnO) nanoparticles were synthesized chemically via the homogeneous precipitation method using different concentration of capping agent (2‐Mercaptoethanol). The structural properties of the as‐prepared ZnO nanoparticles were characterized by X‐ray diffractometer (XRD) and transmission electron microscopy (TEM) measurements. The transparent ZnO/PMMA nanocomposites were subsequently prepared by dispersing as‐prepared ZnO nanoparticles in PMMA via solution mixing and then solution casting method. The optical properties of ZnO/PMMA nanocomposites, namely visible light transparency and UV light shielding efficiency, were studied using an ultraviolet–visible (UV–Vis) spectrophotometer. The optical properties of the as‐obtained nanocomposites were shown to depend on ZnO particle size. The nanocomposite containing small sizes ZnO nanoparticles with an average particle size of (∼10 nm) possessed the most optimal optical properties, namely high‐visible light transparency and high‐UV light shielding efficiency, which are desirable for many important applications.

Phthalocyanines and their derivatives have been extensively studied as organic semiconductors since the first report of organic field effect transistors (OFETs) in 1986. An extended conjugated π system, unique optical and electrical properties along with high thermal stability render them ideal organic semiconductor materials as active layer for OFTs. In this study, Silicon Phthalocyanine dichloride thin films are prepared on glass substrates kept at different temperatures by vacuum deposition method. Using spectrometric techniques, the optical constants of the prepared thin films are measured, From the UV‐Visible absorption studies it is found that the transitions in these materials are direct band‐ band type. The temperature dependent conductivity studies on the prepared thin films yield activation energy and its variation with respect to the deposition temperature is also studied in this work.

Copper 2, 9, 16, 23‐tetra‐tert‐butyl‐29H, 31H‐phthalocyanine (CuTTBPc) thin films have been prepared by vacuum sublimation technique. The films were annealed at 50 to 250°c for 1 hr. The optical, electrical and morphological properties have been investigated as a function of different annealing temperature. The optical measurements have been carried out in the ultraviolet and visible region. The analysis of the spectral behaviour of the absorption coefficient in the absorption region near fundamental edge reveals direct transitions. The energy band gap is investigated. The d.c electrical conductivity is carried out as a function of temperature to investigate the electronic structure of CuTTBPc thin films and to understand the conduction mechanism. The morphology of the films are studied using Scanning Electron Microscopy (SEM).

Since last two decades free‐space optical communication (FSO) has become more and more interesting as an alternative to radio frequency communication. This paper gives an overview of the power budget of an FSO system, designer has to consider while designing an FSO link. In this paper we have calculated the power needed for the transmission of a signal in free space. The received power and distance graph shows that more power needed when the link distances increases; also power and Bit Rate graph obtained at a distance 500 meter. In order to evaluate the power vs. Bit Rate graph we consider a link of distance 500 meter, optical window 1550 nm and three different atmospheric condition 10 dB/Km, 40 dB/Km and 60 dB/Km. The VCSEL laser is used for direct line of sight communication and at the receiver side the APD is used for power reception. The NRZ–OOK modulation format is used for laser beam modulation.

The third‐order nonlinear optical properties of a charge‐transfer organic compound ethyl 2‐[(2E)‐2‐(4‐hydroxy‐3‐methoxybenzylidene) hydrazino]‐5‐nitrobenzoate were investigated by employing Degenerate Four Wave Mixing (DFWM) and Optical Kerr Gate (OKG) techniques. The study enables to compare the χ(3) values obtained on different time scales of the laser pulses and to understand the origin of nonlinear response of the samples.

CuO nanoparticles were successfully prepared by a chemical method which has been widely studied as photothermal and photo conductive materials. The samples were characterized by X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV‐Visible spectroscopy and Photoluminescence Spectroscopy. The SEM image showed that the prepared product consists of spherical nanoparticles with narrow size distribution. The average crystallite size of CuO nanoparticles calculated from XRD pattern was 8 nm. The UV‐Visible absorption spectrum of CuO nanoparticles shows a strong blue shift compared to that of bulk. The band gap energy was calculated from the absorption spectra. Due to the high surface to volume ratio, CuO nanoparticles have high density of surface defects, interstitials and oxygen vacancies. Photo luminescence spectroscopy has been employed in order to explore the optical emission properties of CuO nanoparticles. The emission at 535 nm corresponds to the band edge emission and that at 600 nm is due to the oxygen vacancy. In addition to these two peaks there shows an additional peak at 657 nm which indicates the oxidation state of Cu.

We study the effect of carrier envelope offset (CEO) phase of a few cycle pulse on the dynamics of two‐level systems in the domain of extreme nonlinear optics. Strong dependence of polarization on the CEO phase is observed. Intensity of different high harmonics and their interference is clearly seen to be dependent on the CEO phase of the optical pulses. Our results show that the final state of the atomic system, just after the few cycle optical pulse has passed through the system, depends very strongly on the CEO phase of the pulse.

Single crystals of Calcium Barium tartrate (CBT) were grown by controlled diffusion in silica gel at ambient temperature. The structural characterization of the grown crystals was carried out by Powder X‐ray diffraction analysis. The functional groups present in the crystals were identified using Fourier Transform Infrared spectral analysis. The UV‐Vis‐NIR transmission spectrum was recorded to study the optical transparency of the grown crystals.

We report the experimental demonstration of tunable stop gap in the visible wavelength region by changing the angle of incidence of light. The width and peak reflectance of the stop gap do not change till an angle of incidence of 45°. For angle of incidence greater than 45°, new diffraction resonances appear in the reflectance spectra. At 55° incidence, the stop band split into to two peaks with equal reflected intensity. This multiple Bragg diffraction is in good agreement with the theoretical calculations.

Nanoscale oxides of transition metals, particularly manganese, are desirable for many applications in designing electric, magnetic and heterogeneous catalytic materials. Manganese oxides exist in different phases, viz. MnO, MnO2, Mn2O3, Mn2O7 and Mn3O4. Using different synthetic routes it is possible to synthesize different phases of manganese oxides. Moreover, composites of these oxides with polymer have the potential to address the needs of emerging dielectric technologies. In the present work, using manganese chloride and hydrazine hydrate, Mn3O4 and Mn2O3 nanoparticles were successfully synthesized by conventional and hydrothermal method respectively. The variation in the formation of the different phases has been discussed. The nanoparticles were well characterized by X‐ray Diffraction and using the Debye Scherrer formula, the average size of Mn3O4 and Mn2O3 nanoparticles were calculated to be 35 nm and 25 nm respectively. Using solution casting method, nanocomposites of chitosan/Mn3O4 were prepared ...

Effect of added brine on the structural transitions of SDS, in different compositions of gelatin has been investigated by viscosity, circular dichroism, TGA and DSC. The slow and steady growth of the normal spherical micelles to the higher order aggregates were predicted by viscosity and conductivity measurements. The large negative value for ellipticity observed from CD measurements indicated absence of any conformational change for gelatin. Other measurements were used to study the molecular packing in the micellar aggregates. The complex formed exhibits fantastic properties to be explored in the field of smart gels.

Multilayer structure of Tin Selenide thin films were prepared by thermal evaporation technique by successive coatings of Tin and Selenium metal powders. The number of layers varied from 3 to 11 during deposition on the glass substrate with 423 K temperature. The optical properties of the multilayer films studied using UV‐Vis spectrophotometer. The absorption edge towards blue region shows the nanocrystalline effect of the films. The optical band gap values lies in the ranges of 2.6‐3.2 eV. The structural studies reveals that the prepared films oriented at (0 0 1) plane with hexagonal structure. The crystalline size varies from 11‐22 nm on the different multilayer films and discussed in this paper.

In this communication we describe the design and synthesis of a new conjugated polymer (P) carrying 3,4‐dialkoxythiophene, 1,3,4 oxadiazole and pyrazole units, from its monomers through condensation polymerization method. The structure of newly synthesized polymer was established by FT‐IR, 1H NMR, elemental analysis and gel permeation chromatographic techniques. Further, its electrochemical, linear and nonlinear optical properties of the polymer have been investigated. The optical and electrochemical band gap was found to be 2.39 eV. Z‐scan results reveal that the polymer exhibits strong optical limiting behavior due to effective three‐photon absorption (3PA). The value of 3PA coefficient was found to be 1.1×10−20 m3/W2, which is comparable to that of good optical limiting materials. The fluorescence quantum yield of the polymer in solution was determined using quinine sulfate as standard and it was found to be 42%.

All‐Optical network is still in adolescence to cope up with steep rise in data traffic at the backbone network. Routing of packets in optical network depends on the processing speed of the All‐Optical routers, thus there is a need to enhance optical processing to curb the delay in packet forwarding unit. In the proposed scheme, the header processing takes place on fly, therefore processing delay is at its lower limit. The objective is to propose a framework which establishes high data rate transmission with least latency in data routing from source to destination. The Routing table and optical header pulses are converted into Pulse Position (PP) format, thus reducing the complexity and in turn the processing delay. Optical pulse matching is exercised which results in multi‐output transmission. This results in ultra‐high speed packet forwarding unit. In addition, this proposed scheme includes dispersion compensation unit, which makes the data reliable.

Thin films of TiO2 have been deposited on well cleaned glass substrates by Sol‐Gel dip‐drive coating technique. The films have been prepared at three different pH values (3, 5, and 9) of Sol and annealed in muffle furnace at three distinct temperatures (350 °C, 450 °C, and 550 °C) for one hour and are allowed to cool to room temperature. The films were characterized by XRD, EDAX, SEM and UV‐Vis Spectrophotometer. The as deposited films were found to be amorphous in nature. The annealed films exhibit anatase in crystalline structure. The EDAX results have shown that all the films are maintained with TiO2 in composition. The XRD results reveal that they are nano‐crystalline in nature and the crystalline nature increases with annealing temperature and pH of the Sol. The transmittance and absorbance spectra have shown that the films are transparent and band gap of the films are of the order of 3 eV. The ab initio studies of TiO2 (using GGA) was performed with Vienna ab initio Simulation package and the band s...

In recent years, the full pattern structure refinement using Rietveld Method, with the advent of increased performance of powder diffractometers has allowed enormous progress in the analysis of powder diffraction data. In the full pattern structure refinement, with the possibility of varying peak shape parameters and site occupancies along with the structural and instrumental parameters, provides information not only on the crystal and magnetic structure, but also gives precise knowledge of the particle size and micro‐structural strain. In this report Rietveld profile refinement of some bulk and nano crystalline materials has been presented.

The nanocrystalline CuO thin films were prepared on glass substrates by the sol‐gel method. The structural, morphological, electrical and optical properties of CuO thin films, submitted to an annealing treatment in the 400–700 °C ranges are studied by X‐ray diffraction (XRD), Scanning Electron Microscopy (SEM), Four Probe Technique and UV‐visible spectroscopic. XRD measurements show that all the films are crystallized in the monoclinic phase and present a random orientation. Four prominent peaks, corresponding to the (110) phase (2θ≈32.70°), (002) phase (2θ≈35.70°), (111) phase (2θ≈38.76°) and (202) phase (2θ≈49.06°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the microstructure, electrical and optical properties. The optical band gap energy decreases with increasing annealing temperature. These mean that the optical quality of CuO films is improved by annealing.

Surfactants self‐assemble in bulk aqueous solution to form different microstructure. The self assembled structures may easily rearrange if parameters like concentration, ionic strength, or temperature are changed, which renders self‐assembled systems particularly interesting. Here we examine the influence of n‐nonanol and n‐decanol on the viscosity behaviour of CTAB/KBr system. The alcohols of varying concentrations were added to CTAB/KBr solutions and were kept in a hot bath at a temperature of 45 °C with proper shaking for homogeneity. The viscosity of the micellar solution was measured using Brookfield DV–II + viscometer at temperatures ranging from 25–60 °C. It is observed that the η0 is a strong function of concentration of alcohols. In the case of nonanol four regions were identified in the plot of zero shear viscosity Vs. concentration of alcohol. At low C0, viscosity is low (Region I). With increase in concentration of alcohols the spherical micelles will grow into cylinders and at higher C0, they...

We present our results from the measurements of Supereonlinuum emission (SCE) resulting from the propagation ol” tightly foe used 40 femtosecond laser pulses through distilled water. The e fleet of linearly polarized (LP) and circularly polarized (CP) light pulses on the SCE: in different external focal geometries (f/6 & f/12) is studied in detail. A considerable shift in the minimum wavelength of SCF under tighter focusing limit is observed.

The pre‐photoexcitation effect has been measured in the form of dark polarizarion under visible radiation in 75 MeV oxygen ion irradiated kapton‐H polyimide. The variation of dark decay characteristics has been studied at different polarizing fields. The nature of the decay shows the presence of shallow and deep energy traps in the structure of kapton‐H polyimide. High energy ion irradiation causes the demerization of carbonyl groups and formation of free radicals which results in the increase in charge trapping density.

Two well known electroluminescent (EL) compounds, aluminum and zinc metallo‐8‐hydroxyquinolates have been synthesized. Their chemical and physical properties like NMR, FTIR, Cyclic Voltammetry, absorption and EL are studied. Organic LEDs are fabricated using both the material as emissive layers. Electroluminescence spectra of the complexes are measured. 2Alq3 and Znq2 give peak emission in yellow‐green region at wavelengths 527nm and 540nm respectively. Znq2 is slightly red shifted compared to Alq3 because metal to ligand charge transfer is more in Znq2. A study of ON voltage, luminance efficiency and stability of OLEDs using both materials is made.

The polymer‐ceramic composites have superior characteristics and play a vital role in various applications. In the present study, a new polymer‐ceramic composite is developed using PVDF and zirconium titanate. The composite samples are characterized using PXRD. The polymeric ceramic composite is coated over mild steel substrate and the corrosion resistance behavior is studied using Potentiodynamic and EIS polarization measurements.

A Model Based Iterative Image Reconstruction (MoBIIR) algorithm is developed for impedance image reconstruction of Electrical Impedance Tomography (EIT). Simulated boundary data are generated for circular phantom configuration and the conductivity images are reconstructed with different regularization techniques and regularization parameters. Results show that the algorithm successfully reconstructs the conductivity distribution of the domain under test with its proper inhomogeneity and background conductivity. CNR and PCR of the reconstructed images are found high in both STR and LMR methods. Results show that the normalized projection errors in STR and LMR are same with higher value of λ where as the LMR method has low normalized projection errors compared to STR method with lower value of λ.

The characterization of a continuous membrane deformable mirror (CDM) involves the measurement of influence function, which quantifies the response of individual actuators to application of different voltages. In this paper, we present the results of influence function measurement for a 140‐actuator CDM using a Shack Hartmann sensor (SHS). The measured influence function was fitted using a Gaussian function and also decomposed into Zernike moments. The SHS‐CDM interaction matrix was also computed.

Research in the field of Material Science has gained an upthrust because of the use of high energy charged particles such as swift heavy ions. Swift heavy ions (SHI) lose energy in materials mainly through inelastic collisions with the atomic electrons leading to the modifications in the properties of the material. Now a day it has become a probe to investigate and enhance various properties of the materials. In the present study CaS: Ce nanophosphors, synthesized via solid state diffusion method were irradiated with 120 MeV Ni+9 ions at three different fluences of 1×1011, 1×1012, and 5×1012 ion/cm2. The phosphors were structurally and optically characterized using X‐Ray Diffraction and Photoluminescence spectroscopy respectively. The average particle size decreased with increasing ion fluence. It is found that the PL emission peak observed at 505 nm has increased in intensity with increasing ion fluence which can make it a better candidate for practical applications such as in optical devices.

Light interaction of nanoparticles embedded in a tissue decides the amount of thermal energy absorbed, which is key to plasmonic photothermal therapy, a recent concept for treatment of cancer. The light interaction depends on the shape‐size‐type of nanoparticles, type of tissue and the wavelength of light used. A numerical model is developed to capture light interaction of a nanoparticle embedded tissue and subsequently estimate spatial heating of the tissue.

Chalcogenide glass system Se85−x Te15 Inx ( 0, 12 )glasses are prepared by melt quenching technique and thin films of glassy alloys are prepared by flash evaporation technique. Optical constants are calculated using a transmission spectrum in the wavelength range 375–1200 nm.

The effect of offset (length difference) in two‐fiber displacement sensor is presented in this paper. The performance metrics such as, blind region, peak voltage, linear operating region and sensitivity were studied experimentally for three configurations, Equal fiber(EF), Shorter Transmitter(ST) and Shorter Receiver(SR). The results show, the sensitivity of ST decreases and the sensitivity of SR increases with increase in the offset between the fibers. The operating linear region and peak voltage are shifted to shorter distance and the blind region is decreased with increasing the offset in both SR and ST configurations. The SR probe shows less dead region in comparison with the EF and ST. The bandwidth (FWHM) is unaffected due to offset in both ST and SR configurations and it is equal to EF.

An advanced inorganic material of the class of tetravalent metal acid (TMA) salt, ceriummolybdophosphate (CMP) has been synthesized b co‐precipitation technique, under different synthesis temperature conditions, for the first time. CMP has been characterized by XRD, SEM, EDX, FT IR, UV‐visible, and TGA/DTA. From X‐ray diffraction the particle size is calculated and it lies in the nano regime. Morphology of the sample is obtained from SEM pictures. Chemical composition of the sample has been obtained from EDX. Optical studies have been carried out using FT IR and UV‐visible spectroscopy. Thermal behavior of the samples has been investigated using TGA/DTA.

We demonstrate the construction of an efficient bilayer polymer solar cell comprising of Poly(3‐hexylthiophene) (P3HT) as a p‐type semiconductor and asymmetric fullerene (C70) as n‐type counterparts. The bilayer configuration was very efficient compared to the individual layer perfornance and it behaved like a regular p‐n junction device. The photovoltaic characteristic of the bilayers were studied under AM 1.5 solar radiation and the optimized device parameters are the following: Voc = 0.5V, Jsc = 10.1 mA/cm2, FF = 0.60 and power conversion efficiency of 3.6 %. A high fill factor of ∼0.6 was achieved, which is only slightly reduced at very intense illumination. Balanced mobility between p‐and n‐layers is achieved which is essential for achieving high device performance. Correlation between the crystallinity, morphology and the transport properties of the active layers is established. The External quantum efficiency (EQE) spectral distribution of the bilayer devices with different processing solvents correlates well with the trends of short circuit current densities (Jsc) measured under illumination. Efficiency of the bilayer devices with rough P3HT layer was found to be about 3 times higher than those with a planar P3HT surface. Hence it is desirable to have a larger grains with a rough surface of P3HT layer for providing larger interfacial area for the exciton dissociation.

Rb lamp is a very critical component of the Rb atomic clock’s Physics Package. The Rb lamp’s performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110° C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rb lamp under various operating conditions are reported in the paper.

Anti‐bacterial action of ZnO on the bacterial strain Staphylococcus aureus were made by using bio‐technical method. Light scattering properties of these particles were studied as a function of scattering angle by using an indigenously designed and fabricated laboratory light scattering setup in order to find the scattering profile of ZnO nanoparticles and also the mode of action of these particles on its anti‐bacterial property.

A series of flexible composites are formed by mixing High Temperature Superconducting YBCO and Linear Low Density Polyethylene (LLDPE) and the behaviour of these composites are investigated using Raman Spectroscopy. This study indicated the presence of well defined Raman lines. Raman spectra of pure YBCO and composite samples showed sharp bands and the intensity of these bands is found to decrease with decreasing proportion of the polymer in the composite, indicating the presence of characteristic structural units.

In this paper, Ring resonator with Nano‐photonic Crystal is designed and computational study is made for different structures. The main work is to remove holes of the rectangular lattice and hexagonal lattice from a three‐dimensional (3‐D) silicon slab. Each crystal in the silicon slab are of nanometer size. The various parameters like material and refractive indices are deployed for these crystal structures. Parameters like Ring radius and the Coupling Distance is varied and the performance of the nano‐ring resonator using FDTD modeling tool is investigated.

The effect of Nd3+ substitution on the structural properties of Magnesium ferrite was studied in the series MgNdxFe2−xO4, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol‐gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X‐ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples are in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz—120MHz was also studied

Se100−xPbx (x = 0.1,5 & 10) chalcogenide glasses are prepared by conventional melt quenching. Chalcogenide glasses containing Pb are very important material for tunable radiations in the mid infrared region. DSC thermo grams of these glasses are taken at different heating rates. Activation energy of crystallization is calculated using Matusita and Kissinger methods. Hruby’s constant and the value of (Tc‐Tg) are also calculated. Using these values the stability of the system is discussed.

Zinc oxide (ZnO) nanoflowers were fabricated on non‐seeded glass substrates by successive ionic layer adsorption and reaction (SILAR) method using different complex agents. Influence of complex agents ammonia, lithium hydroxide and hexamine on the optical properties of the as‐synthesized and the samples annealed at 400 °C was studied. Optical red shift was observed in ZnO samples and was analyzed with respect to the complex agents. All samples possessed a steep absorption edge in the wavelength range 375–425 nm. ZnO nanostructures except that synthesized using hexamine have low and steady absorbance and show higher transmittance (70–85%) in the entire visible region. SEM, XRD and EDAX studies confirmed the high surface‐to‐volume ratio, good optical quality, excellent crystalline nature and purity of the formed and annealed ZnO nanostructures.

In this paper, synthesis of Eu2+ activated BaCaP207 pyrophosphate based phosphor by using modified combustion synthesis has been reported and studied for its X‐ray diffraction pattern (XRD).Photoluminescence (PL) properties under near ultraviolet (n‐UV) excitation . The BaCaP207:Eu2+ exhibits unique color: a blue band centered at 455 nm originating from Eu2+ when excited at 354 nm, which is suitable for solid state lighting and near ultra violet light emitting diodes (n‐UV LED).Surface morphology has been also studied by scanning electron microscope and the room temperature FTIR spectrum for studying the nature of the chemical bonds, and their molecular environment was investigated.CIE(Commission Internationalede L’Eclairage) chromaticity coordinates values are estimated from emission spectra of BaCaP207:Eu2+ for the prepared sample

We have employed density functional theory calculations for absorption spectra of copper doped single walled boron nanotube. We have taken zigzag (5,0) single walled boron nanotube with substituting one boron atom by copper (Cu) atom. The nanotube structure contains one atom of copper and 19 atoms of boron. The absorption is determined for parallel and perpendicular polarized light. The absorption is found minimum at higher energy and higher at lower energy under perpendicular polarization. However, the absorption is found higher at higher energy and lower at lower energy under parallel polarization. Thus, the maximum absorption is found for parallel polarized light.

Zinc sulfide (ZnS) thin films were deposited on glass substrates by radio—frequency (RF) magnetron sputtering technique at pressure of 10−6 torr. The deposition parameters were optimized and the films were annealed in air atmosphere (300°C for 1hr). The obtained (as‐deposited and annealed) thin films were characterized for structural and optical properties. The thickness of the films was calculated by ellipsometry. XRD patterns revealed that the films were crystalline in nature with hexagonal structure. The morphological characteristic was carried out by optical microscopy. The optical absorption studies in the wavelength range 300‐900 nm show that energy band gap of the film was found to be decreased with the annealing temperature.