Tunable WDM converters based on amorphous SiC multilayer photonic active filters are analyzed. The manipulation of the magnitude is achieved through appropriated front and back backgrounds. Transfer function characteristics are studied. Results show that the light-activated device combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal. Depending on the wavelength of the external background and irradiation side, it acts either as a short- or a long- pass band filter or as a band-stop filter. A combinational logic function is mapped onto an active two stage optoelectronic logic circuit. An algorithm to decode the multiplex signal is established. An optoelectronic model supports the optoelectronic logic architecture.