Amplified spontaneous emission and lasing in conducting polymers and fluorescent dyes in opals as photonic crystals

Spectral narrowing of photoluminescence (PL) and evolution of sharp emissio n lines upon optical excitation have been observed in opals made of SiO2 sp heres infiltrated with conducting polymers such as OOPPV and MDDOPPV and al so fluorescent dyes such as rhodamine 6G, NK-3483, and coumarin 120. Their emission properties are dependent on the sort of the opal and the solvents used for infiltration. With increasing optical excitation intensity, spectr al narrowing and evolution of sharp lines have been observed in the green o pal infiltrated with OOPPV, MDDOPPV, or rhodamine 6G but not in the infiltr ated red and purple opals. With a solvent having a refractive index similar to that of SiO2, the evolution of the sharp emission lines is greatly supp ressed and the lines exhibit a blueshift with decreasing refractive index. In NK-3483 and coumarin 120 which show red and purple PL, respectively, evo lution of sharp lines is observed when they were infiltrated in red and pur ple opals, respectively, but not in other opals. These results are discusse d in terms of amplified spontaneous emission and multimode lasing due to op tical feedback in the opal matrix with a periodic structure. (C) 1999 Ameri can Institute of Physics. [S0003-6951(99)03218-0].