SIMULATION OF TRANSVERSAL MODAL FIELDS IN INTEGRATED OPTIC COMPONENTS

Propagation of radiation in waveguides is theoretically described by Maxwell's equations. The gradient of refractive index and an influence on the waveguide by a superstrate requires a numerical solution of the differential equation. Iterative methods such as the Runge-Kutta approaches or quantum mechanic equations (WKBJ) are used to calculate the effective refractive index in the waveguide depending on the superstrate's and the waveguide's local refractive indices. Gases penetrating a polymer which acts as a superstrate changes the effective refractive index. The precision of both the numerical approaches has been tested. The calculations avoid the time consuming measurements required to determine optimized waveguide structures and superstrate consistence suitable for observing polymer/gas interactions. The calculated fields of the TE(OO) modes give information about the properties of the polymer-gas-polymer interaction, and the propagation of the light in the waveguide. The results provide a better understanding of polymer-gas interaction and the device's application to sensors. The advantages and disadvantages of the various approaches are discussed and an application of an integrated optical sensor for halogenated hydrocarbons is given.