Continuously tunable organic solid-state laser based on the adjustment of effective refractive index
We report a facile way for continuously tuning the lasing wavelength of an organic solid-state laser by varying the effective refractive index. The effective refractive index of the organic gain medium can be fine controlled by the dopant concentration in the DCJTB:PS film. Continuous wavelength tuning of laser and amplified spontaneous emission (ASE) are achieved in the distributed feedback (DFB) gratings and planar waveguides, respectively. In the DFB laser, laser emission is demonstrated in the red spectral region with a tunable wavelength range of 30 nm, centered at 612 nm. The laser exhibits a well-defined pump threshold and good emission characteristics. Furthermore, ASE with a large wavelength range of 40 nm is also achieved by varying the dopant concentration, thus giving one the freedom to set or tune the lasing wavelength to meet a particular purpose with a common structure. Our results allow for a simple, broadband continuous tuning of the laser emission wavelength.