METAL-CLAD GRADED-INDEX PLANAR OPTICAL WAVE-GUIDES - ACCURATE PERTURBATION ANALYSIS

We Present a perturbation analysis of Propagation constants and attenuation coefficients of TE and TM modes in a metal-clad linear index planar optical waveguide. The imaginary part N" of the complex modal index N = N + iN" is given by N" = (partial derivative N'/partial derivative-epsilon')epsilon", where epsilon = epsilon' + i-epsilon" is the complex dielectric constant of the metal cladding and partial derivative N'/partial derivative epsilon' is obtained by numerical differentiation of the solution of the real eigenvalue equation. The cumbersome solution of a complex transcendental equation is thus completely eliminated. The results are in good agreement with those obtained by solving the eigenvalue equation in the complex plane. By taking the metal-clad linear planar waveguide as a preselected waveguide, we can use our RWKB method to solve metal-clad planar waveguides with parabolic, exponential, gaussian and complementary error function index profiles.