జర్నల్ ఆఫ్ లేజర్స్, ఆప్టిక్స్ & ఫోటోనిక్స్

In this paper, we present analytical soliton solutions in a nonlinear PT-symmetric coupler with gain in one fiber and loss in the other one in the normal dispersion regime. As usual, we derive a temporal dark soliton solution for the coupler in the normal dispersion regime. We study the stability of the soliton solution by imposing a perturbation in the system by using the eigenvalue method. The results show that there exist two forms of perturbed soliton solutions, bright and dark. The numerical calculations show that the perturbed solutions in the bright form are stable and the dark form are unstable. Previous works in bright solitons show that there exists only one perturbed bright soliton solution which is stable only in particular regions.

In this paper, the design and development of dual wavelength noninvasive fiber optic probe based oxyhemoglobin sensor has been presented. This instrument can be used for real time monitoring contents in the blood. It is well known that in blood, the oxygen is carried by the hemoglobin. It uses the dual wavelength spectroscopy which can be performed on blood to determine the oxyhemoglobin saturation. The two sources used are of wavelength 632.8 nm and 830 nm. Two probes containing a bundle of fibers are designed out of which two are source fiber and one is detector fiber. Two finger holders are also designed to prevent any variation in intensity due to finger movement. The backscattered intensity and transmitted intensity of red light and near infrared light are measured. With the help of the ratio of the backscattered intensities and transmitted intensities of red light and near infrared light, oxyhemoglobin saturation is determined.

In x-ray multilayer, the thickness of top layer plays an important role in determining its reflectivity performance. In experimentally grown multilayer, the top layer parameters are found significantly different from those of underneath layers due to growth related issues and contamination effect. The calculations suggest that for top layer characterization the sensitivity of reflectivity technique depends on layer material. Considering the top layer of silicon the first Bragg peak reflectivity of Mo/Si multilayer changes by 2-3% while change in top layer thickness by a factor of two and more, In case of SiO2 as a top layer material the 1st Bragg peak reflectivity changes by 13%. The analysis of total electron yield (TEY) data reveals that the technique can be used to probe 2-4 Å variation in top layer thickness. The both technique-reflectivity and TEY, together gives an complete information of multilayer structural parameters.

This paper has demonstrated correlation between cracks at an LED germanium (Ge) substrate to its thermal resistance. The finding shows, the Rth value, increases with the crack severity. Further analysis, shows the presence of many cracks inside the Ge-substrate, that were die attach at bond-force 140 gF as compared to at 60 gF. This impedes the heat flow and thus cause increase in Rth value. A unique test apparatus that uses Temperature Sensitive Parameters (TSP) method was designed to capture the voltage variation of cracked-dice. The results proofed, this apparatus successfully detects cracked-dice without compromising the testing throughput time.

We present here our quantum propagation and entanglement system for virtual reality remote space computers and TVs with photonic displays in laser activated imagery. This concept is based on 1935 Einstein-Podolsky-Rosen Argument in Quantum Theory. Einstein maintains “the interpretation, according to which |ψ|² expresses the probability that this particle is found at a given point, assumes an entirely peculiar mechanism of action at a distance, which prevents the wave continuously distributed in space from producing an action in two places on the screen. Einstein continues: “in my opinion, one can remove this objection only in the following way, that one does not describe the process solely by the Schrödinger wave, but that at the same time one localizes the particle during propagation

This paper introduces the structure and working principle of Mie-Rayleigh-Raman lidar, observes and compares the Nanjing aerosol of Mie channel with that of the Raman channel respectively. It shows that there is some uncertainty about lidar boundary parameters, however, Raman scattering lidar could overcome such problems effectively that we often use multi-channel Mie-Rayleigh-Raman lidar. The observation results obtained by groundbased Mie-Rayleigh-Raman lidar are consistent with that from space-based lidar, and the former is more accurate than the latter. Integrated observation of the two will be the main direction of the development of aerosol observation in the future.

We present a generalized method for calculating phase matching conditions in biaxial crystals, especially in nonlinear monoclinic and triclinic crystals. Exploiting the angle definition introduced by Japanese mathematician Kodaira Kunihiko, we deduce the angular relations in geometry and obtain the expressions of refractive indices depending on angular orientation of wave vector k and optical axis angle. Then we calculate the phase matching parameters with bismuth borate BiB3O6 (BIBO) crystal in spontaneous parametric down conversion (SPDC) process for the type I and type II. On its basis, we discuss the angular gradients of the pump and emission wave refractive index near the exact phase matching direction, and compare the SPDC with double frequency process in geometrical relations of the refractive index ellipsoids. It indicates the anisotropic structures of nonlinear crystals making a capability of filtering effect, and the nonzero linear mismatch described by refractive index angular gradients can be used to estimate the beam width in crystal. This method is convenient to calculate the phase matching parameters in orthorhombic crystals without solving the quadratic Fresnel equations.

In this paper, we use a digital laser to generate high-radial-order Laguerre-Gaussian, LGp,0 modes by loading digital holograms on a phase-only spatial light modulator that act as an end mirror of a diode-end-pumped laser resonator. The digital holograms were encoded with an amplitude ring mask, which contained absorption rings that match the p-zeros of the Laguerre polynomial. We demonstrate the generation of high-quality LGp,0 modes with a mode volume that is directly proportional to the mode order, p. This work demonstrates the possible of using the digital laser as a tool for simulating optical elements that will be used in pursuing high brightness lasers.

Over the past decades, the common approach to the production of the white Light Emitting Diodes in the lighting industry has been the use of a blue InGaN Light Emitting Diode together with a color correction’ red emitting phosphor and yellow-emitting phosphor Y3Al5O12: Ce3+. However, white Light Emitting Diodes near the Ultra Violet Light Emitting Diode can be combined with the red, green, and blue phosphors. Their combination is due to their improved binging and less the Ultra Violet Light Emitting Diode’s current droop, as well as a better control of the color temperature and color rendering index through the phosphor blends manipulation (Kang 79). The phosphors mentioned above require very high absorption in the range near-Ultra Violet region (Thakur et al. 42). The strong absorption can be obtained from the dipole-allowed 4f and 5d transitions in the rare earth activated ions, such as the Eu2+ and the Ce3+, in a suitable host (Brown and Shand 73). For this approach, the examined phosphors are Ba2MgSi2O7: Eu2+, β-Si AlON-+: Eu2+ and (Sr, Ba) 2SiO4: Eu2+ for the green emitting component, CaAlSiN3: Ce3+ and Sr3Si05: Eu2+ for the orange/ yellow-emitting component, and (Sr, Ca) 2 Si5N8: Eu2+ for the red-emitting component.

The paper is focused on the development of measurement technique and processing of signal for the detection of chemical, explosive, biological agents and its simulants using Engineered Quartz Enhanced Laser Photoacoustic Spectroscopy (QE-LPAS) technique. Hazardous materials like Sarin, TATP (Tri acetone tri-peroxide) and their simulants like DMMP (Dimethyl Methyl Phosphonate), Acetone, and atmospheric species were detected at 7 to 11 μm wavelength band. QE PAS technique is developed and demonstrated from a standoff distance of up to 30 meters in gaseous/vapourous and aerosols based on retro-reflector in ~2.0 ppm concentration. Hazardous biomolecules like Tryphatophan and DPA were detected on diffused aluminum adsorbed surface plate. Explosive and its simulants, TNT on adsorbed surface and DMMP, Nitrobenzene, Acetone were detected in vapour/aerosol form. A dedicated single screen, single user, user friendly Graphical User Interface (GUI) for controlling the entire system, acquisition and processing of the incoming signal and demonstration of results has been developed with the help of Laboratory Virtual Instrument Engineering Workbench (LABVIEW).