In this chapter, we review numerical simulations of light propagation in one-dimensional photonic semiconductor optical waveguides coupled to one or several lateral stubs. In the presence of one stub, we show that the transmission spectrum contains several narrow dips, provided that the boundaries of the stub are covered with a perfect metal to avoid the radiation of the propagating light. Such a simulation of the metallic coating can be used in the far-infrared frequency domain, far from the optical regime. The three-dimensional model is presented to demonstrate the ability of the structure to be integrated in photonic circuits. Then, we show that the interaction between several stubs produces a widening of the zeros of transmission into bandgaps. Inserting an appropriate defect stub between a set of periodical stubs leads to a tunneling transmission, with a narrow peak inside the gap which can be useful for selective filtering. This filtering phenomenon is used to propose a demultiplexer based on a Y-shaped waveguide for separating signals with different frequencies. Finally, we show that the filtering effect of a stub can also be reproduced when the metal is described in the framework of a Drude model instead of being perfect, which makes the realization of the above devices in the near-optical regime plausible.