Showing 2 results for Radhakrishnan
G. Sreelekha, G. Vidya, K. Geetha, R. Joseph, S. Prathapan, P. Radhakrishnan, C.p.g. Vallabhan, V.p.n. Nampoori,
Volume 5, Issue 1 (International Journal of Optics and Photonics (IJOP) Vol 5, No 1, Winter-Spring 2011)
Abstract
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.
G. Vidya, Rani Joseph, S. Prathapan, P. Radhakrishnan, C. P.g. Vallabhan, V.p.n. Nampoori, G. Sreelekha ,
Volume 5, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 5, No 2, Summer-Fall 2011)
Abstract
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.
