Gain coefficient method for amplified spontaneous emission in thin waveguided film of a conjugated polymer

A method based on the unidimensional gain equation has been developed in order to fit the experimental data due to amplification of spontaneous emission in a thin film of conjugated polymer waveguide. The results have confirmed not only a dependence of the gain coefficient on the laser intensity but also on the length of the excitation laser stripe. The results are presented as a function of the average intensity in W/cm2, which is a manner to express the threshold intensity for a direct comparison between different materials, independent of the setup used.