International Journal of

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We report the observations of dual wavelength amplified spontaneous emission from the solutions of a conjugated polymer poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) in Tetrahydrofuran and 1, 2 Dichlorobenzene. We have prepared MEH-PPV using a modified procedure and purified several times in each step, the material offers low molecular weight, low polydispersity index and high thermal stability, which are some of the most important requirements for the fabrication of photo luminescent devices. The variation in the features of amplified spontaneous emission with increasing polymer concentration is presented. For intermediate polymer concentrations, narrow emissions were observed for the 0-0 and 0-1 vibronic peaks which were not reported in solutions to the best of our knowledge. The ASE characteristics sensitively depend on concentration as well as pump power. The gain studies show that MEH-PPV is a potential laser media. By varying the concentration of the solution and pump power we can use either of the two different wavelength bands for lasing applications.

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In the context of conjugated polymers, especially those of the poly (phenylenevinylene) (PPV) family, which are promising candidates as emission material in light emitting devices such as LEDs, field effect transistors and photovoltaic devices, we have, in the present study, prepared MEH-PPV [Poly [2- methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylen-evinylene] of low molecular weight and low polydispersity index. We discuss the thickness dependent fluorescence emission from the film waveguides fabricated with the above blends.Of the two peaks observed in this fluorescence spectrum, the shorter wavelength peak (562nm) is dominant in the range of lower thickness and as thickness is increased the longer wavelength peak (600nm) predominates. We also discuss the multimode laser emission from free standing MEH-PPV/Polystyrene film waveguides blends which show the nature of improvement in lasing behavior. The gain studies show that free standing film of MEH-PPV blended with Polystyrene can be used as a compact solid state laser.

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In this paper, homogeneous, wavelength shift biosensor is designed for sensing the protein concentration using two dimensional Photonic Crystal Ring Resonator (PCRR). The sensor is designed to monitor the protein concentration from 0% to 100%. The proposed sensor is composed of periodic Si rods embedded in an air host with a circular PCRR that is placed between the inline quasi waveguides. It is observed that the resonant wavelength of the sensor is shifted (0.9 nm) to higher wavelength while increasing the protein concentration (5%) as the protein has a unique refractive index for each level. With this underlying principle, the performance of the sensor is analyzed for different protein concentration.

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Silver nanowires are the favorable material in many applications based on their plasmonic double resonance in the visible region. In this paper, thin films of Poly-vinyl-pyrrolidone (PVP) doped with Silver nanowires (Ag NWs) in different concentrations have been prepared. The plasmonic imaging system using a high numerical aperture objective lens excite the Surface Plasmon in these structures. The hot spot results from reflected light intensity of surface plasmon resonance (SPR) proved that increasing of concentration of Silver nanowires yields to get better hot spot in plasmonic imaging systems by choosing the appropriate wavelength. These obtained results accompanying with third order nonlinear investigations show the ability of samples usage in thermoplasmonic applications.

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Optical diffusers are optical elements for smoothing the spatial distribution of light through irregular light scattering. Recently, the fabrication and engineering of optical diffusers has attracted many attentions. In this research, an optical diffuser was fabricated using silicon carbide ceramic powder and by placing the diffuser in the optical path of the experimental setup of optical transmission microscope, the spatial intensity distribution was investigated. The uniform and symmetric spatial distribution was achieved after placing the diffuser in the optical path, and the intensity distribution diagrams were obtained corresponding to the Gaussian distribution. Finally, two-dimensional samples based on polydimethylsiloxane substrate and Kapton tape were fabricated using a low cost and simple soft nano-lithography technique and the colorimetry and imaging of the fabricated 2D samples were investigated using this experimental setup.