In this paper we demonstrate an add/drop filter based on SiC technology. Tailoring of the channel bandwidth and wavelength is experimentally demonstrated. The concept is extended to implement a 1 by 4 wavelength division multiplexer in the visible range.The add/drop filter consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n photodetector with two front and back optical gates. Tailoring the filter wavelength is achieved by applying a 400 nm background and changing front and back biased optical gates. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength channels and quench strongly the others. Back violet background has the opposite behavior; it enhances channel magnitude in short wavelength range and reduces it in the long ones. This nonlinearity provides the possibility for selective removal or addition of wavelengths. An optoeletronic model gives insight on the system physics and explains the light filtering properties of the add/drop filter.