the present invention is an optical fiber system and method for carrying both catv and ethernet signals . the digital signals are translated into higher band by a direct up / down conversion so that analog signals and digital signals are treated as different frequency bands of electrical signals . then , all the signals are mixed / divided by a power combiner / divider . and then , by using optoelectronic devices , the signals are processed with optoelectronic conversion . the converted optical signals are transmitted in a fiber or a related optical channel having low channel loss yet high capacity . to sum up , the present invention can transmit digital signals together with analog signals in a single wavelength to save the cost of an optical signal system and to provide a convenience on rearranging the system .