Multiple wavelength optical filters using gratings waveguides

The scattered fields by multilayer dielectric grating waveguides show anomalies that causes total reflection within a small variation band of some given parameters, such as, frequency or incidence angle of the input signal. These anomalies are associated to a strong couple between any mode that could be excited in any waveguide layer and the incident wave. If the variation of the dielectric constant in the grating is small, the operating points, where there is occurrence of anomalies, may be estimated from the propagation characteristics of planar and uniform waveguides. Therefore is possible to project filters by adjusting the waveguides parameters for the occurrence of these anomalies by approximation.