Patent ID: 8121476

Claim:
An Ethernet-based all-optical carrier sense multiple access/collision detection (CSMA/CD) apparatus comprising: a plurality of optical network units (ONUs) that carry different optical signals on upstream waves λU and transmit the upstream waves λU; a power splitter (PS) that multiplexes the optical signals and transmits the multiplexed optical signals; and a central office (CO) that checks whether the multiplexed optical signals are distorted, amplifies some of the checked optical signals, returns the other optical signals, and monitors the occupation of the plurality of optical network units with respect to a common network, wherein the central office includes a semiconductor optical amplifier (SOA) that checks whether the optical signals are distorted due to mutual interference by using a mutual gain saturation, amplifies the optical signals regardless of whether the optical signals are distorted, supplies some of the amplified optical signals, and returns the other optical signals to the plurality of optical network units by using bidirectional characteristics thereof.