Optical characterisation of blue-green-emitting polymer gain media : light amplification, laser emission, and two-photon absorption

Abstract

Blue-green emitting stilbene dyes have been incorporated into different inert polymer hosts. Steady-state absorption and emission spectroscopy revealed a considerable host dependence of the spectroscopic properties of these dyes. Gain spectroscopy was used to investigate the use of a stilbene dye-doped polymer for solid state amplifying or lasing devices. Initial investigations showed that the photostability of the dye was dependent on the host with polystyrene providing the most stable performance of the hosts investigated. The variable stripe length method was employed to measure the net modal gain of asymmetric slab waveguides under nanosecond UV pumping conditions. The modal gain measured was one of the highest reported to date for an organic material. Optically pumped low threshold lasing was also demonstrated in a rudimentary asymmetric slab waveguide laser.