Laser-like emission from dye-doped nanostructured synthetic opals

Abstract

3-D silica based inverse opal sample were prepared using close packed crystals of latex spheres as templates for silica polymerization. The samples were characterized by electron microscopy which reveals a fcc crystalline structure presenting pores with diameter of 210 nm and walls with 70 nm of thickness. The samples were infiltrated with Rhodamine 6G by soaking them in an ethanolic solution during 2 min and leaving it to dry at ambient for 2 hours. The second harmonic of a Nd:YAG laser at 532 nm (6 ns, 5 Hz) was used to excite the samples. The laser beam was focused on a region of 3 × 10-5 cm2 forming an angle of incidence of 49° with respect to, the normal of the crystal surface. The opal structure presents no absorption in the visible range but, due to the presence of dye molecules, the laser light is absorbed. The incident laser intensity was varied and the dye fluorescence was collected throughout a monochromator to monitor its characteristics.