Abstract: An optical surge suppressing apparatus includes an output light level compensating circuit, an optical surge compressing circuit, and an optical amplifier. The output light level compensating circuit compensates for a level drop generated in input signal light. The optical surge compressing circuit suppresses an optical surge generated in the input signal light. The optical amplifier outputs the input signal light in which the level drop is compensated for by the output light level compensating circuit and the optical surge is suppressed by the optical surge compressing circuit.

Abstract: A transmitting apparatus has a plurality of optical signal transmitters, a plurality of transmitting transponders for converting the wavelengths of optical signals transmitted from the optical transmitters into respective wavelengths and transmitting wavelength-converted optical signals, a wavelength-division-multiplexer for wavelength-division-multiplexing the wavelength-converted optical signals, and an auxiliary transmitting transponder for converting a wavelength of an optical signal transmitted from the optical signal transmitters into a wavelength different from the wavelength-converted optical signals, and transmitting an auxiliary wavelength-converted optical signal. The transmitting transponders are monitored by a supervising unit, which outputs a detected failure signal when it detects a failure of one of the transmitting transponders.