Novel lasing action in dye-doped polymer films coated on large pseudotabular Ag islands.

An approximately 15 microm thick polymer film doped (approximately 5 mM) with a laser dye, when coated on large pseudotabular Ag islands and pumped by a nanosecond laser, generated a single sharp stimulated emission with a bandwidth down to 2.5 nm. We attribute this novel, low-threshold (approximately 1 mJ/cm(2)) lasing action to the surface-enhanced fluorescence of the dyes very near the Ag islands. This highly surface-sensitive lasing concept was supported by the fact that the lasing action was almost completely eliminated by separating the Ag islands and the dye-doped polymer film with a molecularly thin (approximately 14 A) spacer.