Novel Lasing Action in Dye-Doped Polymer Films Coated on Large Pseudotabular Ag Islands

Abstract

An ∼15 μm thick polymer film doped (∼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 (∼1 mJ/cm²) 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 (∼14 Å) spacer.