The optimization of integrated optical evanescent-wave sensors is dual. For
optimal performances, we require waveguides with both maximal sensitivity to
the measurand, the quantity intended to be measured, and minimal sensitivities
to perturbations. In this context, fully numerical approaches are extremely
powerful, but demand huge computer resources. We address this issue by
introducing a general and efficient approach, based on the formal derivation of
analytical dispersion equations, to express and evaluate all waveguide
sensitivities. In particular, we apply this approach to rectangular waveguides,
to discuss its accuracy and its use within sensitivity optimization procedures