The present invention is directed at an electrically tunable filter for wavelength filtering of light. The filter comprises a substrate region, a waveguide region over the substrate, an upper region over the waveguide region, and current blocking regions adjacent to the waveguide region. The waveguide region comprises a semiconductor having a bandgap wavelength sufficiently different from the light for high peak transmission of the light. A waveguide rib layer may also be included in the waveguide region to channel the light through the filter. The current blocking regions narrow the waveguide region to increase the current density. The present invention is also directed at a method of manufacturing the filter described above.