Random lasing in an organic light-emitting crystal and its interplay   with vertical cavity feedback
  The simultaneous vertical-cavity and random lasing emission properties of a blue-emitting molecular crystal are investigated. The 1,1,4,4-tetraphenyl-1,3-butadiene samples, grown by physical vapour transport, feature room-temperature stimulated emission peaked at about 430 nm. Fabry-P\'erot and random resonances are primed by the interfaces of the crystal with external media and by defect scatterers, respectively. The analysis of the resulting lasing spectra evidences the existence of narrow peaks due to both the built-in vertical Fabry-P\'erot cavity and random lasing in a novel, surface-emitting configuration and threshold around 500 microJ cm^-2. The anti-correlation between different modes is also highlighted, due to competition for gain. Molecular crystals with optical gain candidate as promising photonic media inherently supporting multiple lasing mechanisms. 
Andrea Camposeo (1), Marco Polo (1), Pompilio Del Carro (1), Leonardo   Silvestri (2), Silvia Tavazzi (3), Dario Pisignano (...
cond-mat.mtrl-sci physics.optics