Patent ID: 8731404

Claim:
An optical transmission system comprising: a user side optical repeater device (ORD) to be connected with a user side optical network unit (ONU), for transmitting data in two ways, and for wavelength division multiplexing (WDM); a central office side ORD to be connected with a central office side optical line terminal (OLT), for transmitting data in two ways, and for WDM; and a wavelength multiplexing and a wavelength de-multiplexing functions (MUX/DEMUX), for relaying between the user side ORD and the central office side ORD, wherein the user side ORD includes, a first up optical transmission circuit, for converting a plurality of optical signals output from the user side ONU into optical signals of different wavelength respectively, and for outputting to the wavelength MUX/DEMUX; a first down optical transmission circuit, for converting optical signals of different wavelength output from the central office side ORD via the wavelength MUX/DEMUX into optical signals of the same wavelength-band, and for outputting the optical signals to an optical transmission path reaching the user side ONU; and a preamble compensating circuit, for taking out a normal data signal from burst signals propagated from the user side ONU, and for adding a preamble signal before and/or after the data signal, and wherein the central office side ORD includes, a second down optical transmission circuit, for converting a plurality of optical signals output from the central office side OLT into optical signals of different wavelength respectively, and for outputting to the wavelength MUX/DEMUX; and a second up optical transmission circuit including a ray path connecting the wavelength MUX/DEMUX and a configuration for branching a wavelength, for outputting optical signals of different wavelength, output from the user side ONU via the wavelength MUX/DEMUX, to an optical transmission path reaching the central office side OLT via the configuration for branching a wavelength, with same wavelengths respectively, such that the second up optical transmission circuit directly transmits optical signals from the user side ORD to the central office side OLT without converting their wavelengths.