Förster energy transfer induced random lasing at unconventional excitation wavelengths

Abstract

We experimentally demonstrate efficient lasing from a Rhodamine-nanoscatterer random laser when pumped with unconventional wavelengths, at which the absorption of Rhodamine is negligible. Förster-type energy transfer was realized by using Coumarin molecules as donors. Explicit time-resolved spectroscopy provided direct evidence for the nonradiative transfer with ∼48% efficiency. We obtained lasing at reduced thresholds by a factor of over 3 and increased amplification rates by a factor of ∼4 in the Förster regime, even in samples with sub-diffusive disorder strength. We characterize the efficacy of the Förster transfer induced lasing over a range of unconventional wavelengths for the Rh-based system.