[21a-W521-1~10] 12.4 Organic light-emitting devices and organic transistors

▲ [21a-W521-2] Quasi Continuous-wave Lasing in Organic Thin-film Distributed Feedback systems

〇(P)SANGARANGE DONATULA SANDANAYAKA^1,2, Toshinori Matsushima^1,2, Chihaya Adachi^1,2 (1.OPERA Kyushu Univ. for Center for Organic Photonics and Electronics Research Kyushu University, 2.JST ERATO)

Keywords:distributed feedback,quasi-continuous-wave operation,organic thin-film laser

Quasi-continuous-wave (quasi-cw) surface-emitting lasing has been demonstrated in a distributed feedback device which combines a second-order grating with an organic thin film of a host material 4,4’-bis(N-carbazolyl)-1,1’-biphenyl (CBP) blended with an organic laser dye 4,4’-bis[(N-carbazole)styryl]biphenyl (BSBCz). When pumping the device with optical picosecond pulse excitation, the quasi-cw laser operation maintained up to a repetition rate of 8 MHz (Fig. 1). The lasing threshold was around 0.25 mJ cm⁻² which was almost independent of the repetition rates. The maximum repetition rate and lasing threshold obtained here is the highest and lowest, respectively, in ever reported quasi-cw lasers with organic thin-film systems. These superior quasi-cw lasing characteristics in BSBCz are accomplished by the less generation of triplet excitons via intersystem crossing because a photoluminescence quantum yield of the blend film is nearly 100% and there is no significant spectral overlap between laser and triplet absorption.^1,2 These findings are believed to be useful for a better understanding of quasi-cw lasing operation in organic thin films and provides a milestone for the realization of electrically pumped organic laser diodes.