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 fi eld goes to zero at the boundary. Solutions of the wave equation are then s imply integer Bessel function of high order. The product n rho, where n is the refraction index and rho is the microring radius, is needed to several decimal places to successfully assign spectral emission lines to the approp riate Bessel function. A Fourier transform of the emission spectra consists of a series of diminishing peaks with a spacing of n rho. With this evalua ted product in hand a calculation of the laser emission can be obtained. (C ) 2001 Elsevier Science B.V. All rights reserved.