Low-threshold amplified spontaneous emission and laser emission in a polyfluorene derivative

Abstract

The amplified spontaneous emission (ASE) and lasing properties of a fluorene copolymer PF3Cz film waveguide were investigated under optical pumping. Low ASE and lasing threshold were observed at 59 W/cm2/pulse and 1.7 KW/cm2/pulse, respectively. The stimulated emission cross section of the PF3Cz film was estimated to be approximately 1.6×10−16 cm2 at the ASE peak of 448 nm. The absorption cross section was estimated to be 2.8×10−16 cm2 at the absorption peak λ=370 nm. Gain and loss measurements at the ASE peak showed that the net gain coefficient reaches 26±1.7 cm−1 when pumped at 1.4 KW/cm2, and the loss coefficient of the waveguide was about 13±1.1 cm−1.