Patent ID: 8483560

Claim:
An optical communication apparatus comprising: an optical signal reception unit that receives an optical signal, the optical signal being a multiplexed signal of a main signal and a supervisory signal; and a supervisory signal transmission and reception unit that is connected to an output end of the optical signal reception unit, detects whether or not the supervisory signal exists, and outputs a main signal transmission stop instruction for directing a transmitting source of the main signal to stop outputting the main signal if the supervisory signal cannot be detected, wherein if the optical signal reception unit detects a loss of the main signal but not a loss of the supervisory signal, and also if the supervisory signal transmission and reception unit detects the loss of the supervisory signal, the optical communication apparatus evaluates that a failure is generated in an optical path, wherein the optical signal reception unit includes a Raman amplifier, wherein the optical signal reception unit includes an optical amplifier that amplifies an output from the Raman amplifier, wherein the supervisory signal transmission and reception unit detects the supervisory signal divided by the optical amplifier, and wherein an output end of the Raman amplifier is directly connected to an input end of the optical amplifier via the optical path.