Low-threshold blue-emitting monolithic polymer vertical cavity surface-emitting lasers

The authors report on a monolithic vertical microcavity blue laser with a carbazole/fluorenyl derivative copolymer active film. The laser is realized by electron-beam deposition of the two dielectric mirrors on the bottom and on the top of the polymeric active layer. The devices exhibit a threshold fluence as low as 1.2 μJ/cm², with a divergence of the emission beam of 2.8°. The measured lasing threshold and operational lifetimes (≫1.5×10⁴ pulses at an excitation density 500 times larger than threshold) are among the best so far reported for blue-emitting polymer lasers, thus making these devices promising candidates for future electrical excitation.