Optimization of Cavity Length to Obtain Low Threshold Solid-state Dye Laser

We have demonstrated and studied polymeric solid-state dye lasers (SSDLs) fabricated by three-dimensional (3D) polystyrene colloidal crystals and tert -butyl roadamine B ( t -Bu RhB) doped Poly (methyl methacrylate) ( PMMA ) films with different film thickness. The sandwich-typed resonator cavities with different active layer thickness display single-mode lasing oscillations in the reflection bandgap of the colloidal crystals. The lasing thresholds could be optimized by changing the thickness of t -Bu RhB doped PMMA films, which is as low as 7.43 W/cm 2 . Adjusting active layer thickness would provide an opportunity to accelerate the development of fabricating polymeric SSDLs with low threshold.