Laser Behavior of (E, E)-2, 5-Bis [2-(1-Methyl-1H-Pyrrole-2-Yl] Pyrazine (BMPP) Dye Hybridized with CdS Quantum Dots (QDs) in Sol-Gel Matrix and Various Hosts

The present paper discusses the effect of CdS QDs on photo physical and photochemical parameters of BMPP laser dye in different media including methanol, sol-gel matrix, poly methyl methacrylate (PMMA) and a copolymer of MMA and 2-hydroxyethyl methacrylate (HEMA) media. CdS QDs have been applied as energy donors to BMPP laser dye in a trial to improve its lasing efficiencies and the sensitized emission of BMPP laser dye using CdS QDs as donors was also achieved in methanol. The amplified spontaneous emission (ASE) efficiencies of BMPP laser dye in the different hosts under study were measured as the ratio between the output energy of the dye over a range of input pumping energy with a highest ASE slope efficiency being in methanol compared with PMMA and HEMA/MMA polymeric matrices. The photo-stability of the samples was examined in terms of the ASE intensity change as a function of the exposure time to blue diode laser and in terms of the time needed to reduce the energy output intensity to half of its value. The highest photo stability was observed in methanol. The least stability is observed in PMMA and HEMA/MMA polymeric matrices. Despite the role of CdS QDs in sensitized emission, they enhance BMPP laser dye. Some spectroscopic and photo physical criteria of BMPP dye have been measured in presence and absence of CdS QDs by applying spectroscopic data and relevant calculations. These include the oscillator strength, attenuation lengths, radiative decay rate constant, absorption and emission cross-sections, dipole moments, intersystem crossing rate constants and the tuning domain gain coefficients (α).

Keywords: Sol-gel, Quantum dots, Energy transfer and Photo stability.