Described are tunable multiport optical filters that filter systems with many optical channels in a convenient and cost-effective manner. The tunable multiport optical filters of the invention are simple in design and have few optical components. The basic elements are a dispersion element and a rotating mirror. With properly arranged arrays of input and output optical fibers, individual wavelength components from a selected input beam are spatially separated and steered by the rotating mirror to selected output locations. The optical properties from the selected components may be measured by one or more photodetectors. The filters are also useful for selecting and routing optical signals.