Lasers and Plasma Related Studies 4.10 SOLID STATE DYE LASER Optically excited solid-state dye lasers are emerging as superior alternatives to liquid dye lasers for many applications in spectroscopic investigations and analysis. The main limitation in solid state dye lasers, in which the dye molecules are dispersed in a polymeric or composite transparent solid material, is rapid photo-degradation of the active medium. In a collaborative effort between L&PTD, BOD and UICT, dye-doped polymeric materials using both physical and chemical doping are being developed at BARC. The major thrust is to improve 10Hz Solid-state dye laser. The inset shows the scan pattern of heat dissipation, suitable laser disk preparation and special laser the pump beam on the disk obtained with the scanning disk. designs for prolonging the operation life of the disks. MPMMA, co-polymers P(MMA : HEMA) and covalently linked dye monomers were developed. These samples are tested in laser amplifier and oscillator configurations. Fig. shows some of the dye doped polymer disks, after sectioning and optical polishing, fabricated in collaboration with UICT. An indigenously developed polymeric (MPMMA) disc doped with (0.5 mM) Rh6G dye was longitudinally pumped with the 2nd harmonic of YAG laser. Lasing efficiency of 10% was obtained with 24 nm spectral width at 558 nm as central wavelength. When excited by the second harmonic of a pulsed Nd:YAG laser at 10 Hz pulse repetition frequency at a single spot, a Pyromethene dye doped cross-linked PMMA disk exhibited Indigenously developed samples dye doped 39% optical efficiency as a laser amplifier, with only a 4% drop polymer (Rhodamine 6G in MPMMA) in efficiency after 1 hr operation. With motorized area scanning, to utilize a larger volume, more than 7 hrs of operation of Rhodamine 6G dye doped modified PMMA disk in a laser oscillator has been achieved without any noticeable drop in S.Singh, V.R.Kanetkar, G.Shridhar et al, Journal of Luminescence, Vol 101, p285, March 2003. efficiency. J.Thomas, Sasi Kumar, Alok Ray, K.Dasgupta, NLS-4 (2005), BARC, Mumbai To improve the photo-stability of dye doped solid host, work on synthesizing covalently linked rhodamine B dye monomer (chemical doping) with MMA was initiated. The dye derivative capable of forming covalent crosslinkage with the monomers has been prepared and tested. This will enhance the heat dissipation of the dye through backbones of polymer macromolecule and lead to long operational lifetime of the solid-state dye laser. This search for new materials will pave the way for a final solid state dye material and laser configuration useful for laser spectroscopy and related work. 50 BARC HIGHLIGHTS Physical Sciences.