Laser oscillations of whispering gallery modes in thiophene/phenylene co-oligomer microrings

Abstract

Laser oscillation of whispering gallery modes was observed in microring structures of semiconducting thiophene/phenylene co-oligomer (TPCO) crystals at room temperature. Microring structures were formed by dry etching from thin film crystals of TPCO. The thresholds for the laser oscillation of a microring and a thin film crystal are 200 and 1400 μJ cm2 for picosecond excitation, respectively. Therefore, the threshold for the microring was reduced to 17 of that for the thin film crystal. The dramatic reduction of threshold clearly demonstrates the importance of microcavity in making efficient organic semiconductor lasers. © 2007 American Institute of Physics.