Control of Molecular Packing toward Lateral Microresonator for Microlaser Array
Nanowire laser arrays for integrated on-chip optical interconnects demand the uniformity of lasing wavelengths from different modules, which, however, is challenging owing to inevitable heterogeneity in sub-unit fabrication. Herein, we demonstrated a facile method to prepare uniform nanolaser arrays based on transverse lateral Fabry-Pérot (FP) microresonator built within single-crystalline organic microribbons of 1,4-bis((E)-2,4-dimethylstyryl)-2,5-dimethylbenzene (6M-DSB). Theoretical, spectroscopic and crystallographic results together reveal that short-axis brickwork-packing and long-axis uniaxial-alignment of 6M-DSB molecules results in a mixed Hj-type aggregation within microribbons. On the one hand, such kind of Hj-type aggregation exhibits enhanced radiative decay and therefore 100% photoluminescence quantum yield for minimizing the singlet-triplet annihilation and re-absorption of laser photons owing to triplet absorption. On the other hand, the uniaxial-alignment gives rise to transverse lateral FP microresonator along the width of 6M-DSB microribbons, rather than longitudinal microresonator in conventional nanowire lasers. By positioning a microribbon onto a PDMS pad with patterned grooves, only the suspended parts support transverse waveguiding and high quality FP resonances. A proof-of-concept 1×4 transverse nanolaser array constructed from the same microribbon was demonstrated with almost identical lasing thresholds, wavelengths and FP resonances, providing coupled lasing sub-units for integrated organic photonics.