Optically end-pumped plastic waveguide laser with in-line Fabry-Pérot resonator

A plastic waveguide laser doped with organic dye molecule was fabricated with self-written active (SWA) waveguide technique. The device has a Fabry-Perot resonator consisting of a pair of highly reflective dielectric mirrors, which has brought two advantages for efficient optical pumping; (i) the efficient optical feedback in the cavity can be induced, and (ii) the reflection band of the dielectric mirrors can be tuned to overlap only with the emission band of the doped dye. For the SWA waveguide devices, furthermore, the active waveguide core is essentially coupled with a fiber port for optical input. Owing to these advantages, an experimental configuration for the optical end pumping can be easily applied. The high absorption efficiency for the pumping light could be obtained in this pumping method. A remarkable lowering of the lasing threshold was observed. As the best results of this study, consequently, the lasing action under the optical pumping energy as low as 50 nJ was achieved.