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Low‐Threshold Distributed‐Feedback Lasers Based on Pyrene‐Cored Starburst Molecules with 1,3,6,8‐Attached Oligo(9,9‐Dialkylfluorene) Arms
Author(s) -
Xia Ruidong,
Lai WenYong,
Levermore Peter A.,
Huang Wei,
Bradley Donal D. C.
Publication year - 2009
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200900503
Subject(s) - materials science , amplified spontaneous emission , laser , optoelectronics , photoluminescence , excited state , wavelength , spontaneous emission , dye laser , pyrene , optics , atomic physics , physics , astrobiology
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 ∼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 T g . The ASE remained observable for annealing temperatures up to 170 or 200 °C. 1D 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 ∼40 nm around 471–512 nm. In addition, these lasers have relatively long operational lifetimes, with N 1/2 ≥ 1.1 × 10 5 pulses for unencapsulated devices operated at ten times threshold in air.