RIGOROUS SPECTRAL-ANALYSIS OF LEAKY STRUCTURES - APPLICATION TO THE PRISM COUPLING PROBLEM

This work presents a rigorous spectral analysis of the leakage phenomenon in integrated optical structures. We first show that the ''leaky mode'' of a dielectric waveguide actually represents a group of radiation modes around a central component satisfying the transverse resonance of the structure. Then we give a rigorous integral formulation for the calculation of the coupled power in structures like the prism coupling structure. The approximations for the case of weak coupling are then analysed to show their limits of validity. With these approximations we get the same formula existing in the literature.