A high-resolution and compact wavelength detector capable of resolving very small changes in the spectral information of the incident light is highly desirable for many applications such as Lab-on-Chip systems, biosensors, chip-sized detectors, on-chip fluorescence spectrometry, wavelength shift detectors, interrogations system, etc. In this work we present the simulation and design of a variable interference filter (VIF) constituted by a wedge-shaped Fabry-Perot cavity placed in between two stacks of thin films, forming dielectric reflectors. This device constitutes an optical filter that converts the spectral information in a position dependent signal that can be measured by a photo detector, a PDA or a CCD. We have investigated the performance of the designed VIF depending on its optical properties in order to optimize its geometrical configuration. With the results obtained we intend to fabricate a multi-channel spectral detector that can be used in environmental analysis.