Conjugated polymer lasers: emission characteristics and gain mechanism

The photoluminescence emission from a conjugated polymer blend system is in vestigated. Line narrowing which can be attributed to amplified spontaneous emission (ASE) is observed upon increasing the excitation density. Pump-pr obe experiments reveal a spectrally broad positive gain, supporting this no tion. The gain dynamics are investigated on a picosecond timescale. A laser based on the polymer blend system is realized by placing the material into an external resonator. The laser emission is characterized with respect to its coherence, tunability and polarization. The dependence of the laser em ission on pump polarization and pump wavelength gives insight into the natu re and the dynamics of the excited states involved in the lasing process. A model for the gain mechanism in conjugated polymer lasers is proposed base d on our measurements.