Multicolor emission in dye-doped polymer thin film DFB lasers

We present a study of Distributed Feedback (DFB) Laser emission in polymer thin films. This laser scheme permits efficient control of the stimulated emission in dye doped polymer materials. Optical feedback is provided by distributed Bragg gratings formed in the film by interference patterns from the pump beam. We report on particular features of the thin film DFB lasers. Devices are optically pumped using a Lloyd-mirror interferometer. For a given DFB grating period, the number of lasing modes depends on film thickness. Spectral content of the devices can be analyzed using planar waveguide theory. An excellent agreement between the theoretical transverse electric mode structure and the laser emission spectrum is found. We report for the first time on another scheme in which two DFB gratings are optically excited. There results a multicolor laser emission. This new scheme can interpreted in terms of a degenerate four wave mixing (DFWM) process in which the coherent interaction between pump waves in the luminescent material is monitored by laser emission.