Lasing features of dye-doped pendant drops added with polymer particles: spectral blueshift and intensity enhancement

When micrometre-sized polymer particles were added into a dye-doped pendant drop that acted as a quasi-two-dimensional circular resonator, we found a blueshift of the peak wavelength of its lasing spectrum. The lasing output was also enhanced by the particles. The spectral blueshift was explained by a model of dye lasing in a circular cavity. The model includes losses of the scattering particles, medium absorption, and radiation leakage. An optimum particle density for maximum lasing output was deduced. The results are consistent with our experimental findings.