Mode characterization of microring polymer lasers

Conducting polymer films coated on circular glass fibers offer a low loss, high Q, resonance structure for investigating photopumped lasers. The high Q structure allows a simplification of the boundary conditions, that the field goes to zero at the boundary. Solutions of the wave equation are then simply integer Bessel function of high order. The product nρ, where n is the refraction index and ρ is the microring radius, is needed to several decimal places to successfully assign spectral emission lines to the appropriate Bessel function. A Fourier transform of the emission spectra consists of a series of diminishing peaks with a spacing of nρ. With this evaluated product in hand a calculation of the laser emission can be obtained.