Low-Threshold Distributed-Feedback Lasers Based on Pyrene-Cored Starburst Molecules with 1,3,6,8-Attached Oligo(9,9-Dialkylfluorene) Arms

Here, a detailed characterization of the optical gain properties of sky-blue-light-emitting pyrene-cored 9,9-dialkylfluorene starbursts is reported; it is shown that these materials possess encouragingly low laser thresholds and relatively high thermal and environmental stability. The materials exhibit high solid-state photoluminescence (PL) quantum efficiencies (>90%) and near-single-exponential PL decay transients with excited state lifetimes of similar to 1.4 ns. The thin-film slab waveguide amplified spontaneous emission (ASE)-measured net gain reaches 75-78 cm(-1). The ASE threshold energy is found to remain unaffected by heating at temperatures up to 130 degrees C, 40 to 50 degrees C above T-g. The ASE remained observable for annealing temperatures up to 170 or 200 degrees C. I D distributed feedback lasers with 75% fill factor and 320 nm period show optical pumping thresholds down to 38-65 Wcm(-2), laser slope efficiencies up to 3.9%, and wavelength tuning ranges of similar to 40 nm around 471-512 nm. In addition, these lasers have relatively long operational lifetimes, with N-1/2 >= 1.1 X 10(5) pulses for unencapsulated devices operated at ten times threshold in air.