Alok K Ray
Articles written in Pramana – Journal of Physics
Volume 75 Issue 5 November 2010 pp 975-983 Conributed Papers
Photonic crystals fabricated from the colloidal spheres of polymethyl methacrylate (PMMA) using the inward-growing self-assembly technique were subse-quently in-filled with zinc oxide (ZnO) prepared by the sol–gel process. The polymer template was removed by heat treatment and chemical method to get ZnO-inverse photonic crystal. The structural quality of the inverse photonic crystal obtained by the chemical method was found to be superior to that obtained by heat treatment. The ZnO-inverse photonic crystal obtained by the chemical method was further treated at an elevated temperature to ensure the crystalline nature of ZnO. Laser-induced emission tudies on ZnO-inverse photonic crystals were carried out at an excitation wavelength of 325 nm. The emission spectra showing UV and visible bands at collection angle of 45° from the direction of excitation helped to establish the role of crystalline ZnO.
Volume 75 Issue 5 November 2010 pp 991-998 Conributed Papers
Many aspects of photophysical, photostability and laser properties of kiton red S dye remain unresolved, particularly for pumping with 578 nm radiation of CVL and 532 nm output of Nd:YAG lasers, and these are studied using different alcohol- and water-based binary solvents. Our results show that methanol is better suited for low and high-repetition-rate KRS dye lasers because of its superior laser efficiency, photostability as well as photothermal properties.
Volume 82 Issue 2 February 2014 pp 271-275 Contributed Papers
Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbituril (CB), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5–7) with CB as the minor product. The literature procedure has been optimized to get pure CB in 12–14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.
Volume 82 Issue 2 February 2014 pp 277-281 Contributed Papers
Quantum yield of fluorescence (QYF) of widely used Rhodamine (RhB) dye in ethanol and water was observed to decrease rapidly with increase in temperature of the dye solutions, which was correlated to enhanced torsional motion of its flexible diethylamino groups. This is harmful for its use in high-average power dye lasers, pumped by copper vapour laser (CVL) or diodepumped solid-state green laser (DPSSGL), in which bulk temperature of the dye solution was found to increase due to the heat generated by circulation pumps and non-radiative decay processes of excited dye molecules. The QYF of RhB dye in water was found to be not sensitive to temperature in the practical operating region 16–25°C of dye laser by adopting supramolecular route to form an inclusion complex of RhB with the container molecule cucurbituril (CB).
Volume 94, 2019
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