NETWORK INTERFACE UNIT IN OPTICAL COMMUNICATION SYSTEM AND METHOD OF INHIBITING INTERFERENCE

摘要

PURPOSE: To suppress the mutual induction interference between electric transmission lines closely arranged on a photon integrated circuit by providing an electric modulator which generates electric signals in a frequency band which is difference to that of the original electric signals by electrically modulating the original electric signals. CONSTITUTION: In a network interface unit(NIU) 203, input electric signals are received by means of an electric modulator 201 which modulates the signals to a first prescribed frequency band, sent to the E/O (electrooptical) converter 101 of a photon integrated circuit 202 which converts the signals into optical signals having their center frequency in a frequency band Fl, and transmitted through an optical waveguide 105. Optical signals transmitted from another NIU 300 are received by means of an O/E (photoelectric) converter 104 through an optical transmission medium 105 and a directional coupler 107 in a frequency band F2 and the electric output signals of the converter 104 are transmitted to a filter means 204. Therefore, no interference occurs between the electric signals outputted from the converter 104 and inputted to the converter 101, because different frequency bands are assured to the electric signals.