Low-threshold distributed-feed back lasers based on pyrene-cored starburst molecules with 1,3,6,8attached oligo(9,9-Dialkylfluorene) arms

Here, a detailed characterization of the optical gain properties of sky-bluelight-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 nearsingle-exponential PL decay transients with excited state lifetimes of ∼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 °C, 40 to 50 °C above Tg. The ASE remained observable for annealing temperatures up to 170 or 200°C. ID 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 ∼40nm around 471-512 nm. In addition, these lasers have relatively long operational lifetimes, with N_1/2 ≥ 1.1 X 10⁵ pulses for unencapsulated devices operated at ten times threshold in air.