Single-mode laser emission at 825 nm from a photopumped cylindrical microresonator based on a polymer semiconductor

摘要

A near-infrared-emitting microlaser has been demonstrated, which is based on a semiconducting nonconjugated polymer. A luminescent polymer layer is formed on a silica optical fiber 125 μm in diameter by self-assembly with poly(9-vinylcarbazole) containing an electron-transport material, 2-(4-Biphenylyl)-5-(4-tertbutylphenyl)- 1,3,4-oxadiazole, and a near-infrared-emitting compound, 2-(6-(p-dimethylaminophenyl)-2,4- neopentylene-1,3,5-hexatrienyl)-3-ethylbenzothiazolium perchlorate. The cylindrical polymer microcavity shows laser emission at 825 nm when it is transversally photopumped at 532 nm with a nanosecond Nd:yttrium aluminum garnet laser. The resonance of the microcavity is characterized by a cavity quality factor Q =(2.7±0.1)×10~3, which is determined from the laser spectral width. Furthermore, a threshold analysis is carried out by taking into account the effects of the ground-state absorption of the chromophore and Rayleigh scattering of the gain medium. The analysis shows that the minimum threshold lies in the vicinity of 824 nm, which is consistent with the experimentally observed laser emission line at 825 nm.