Optical communication network unit comprising an optical signal converting apparatus and/or an optical signal receiving apparatus

摘要

In an optical signal receiving apparatus, an electrical switch is turned on to put a semiconductor laser into an oscillating state to invert an input optical signal. Mutual gain modulation is carried out in a semiconductor optical amplifier due to the input optical signal. A transmission wavelength of a variable wavelength optical filter is matched with an oscillation wavelength of the semiconductor laser and then an inverted optical signal is supplied to an optical receiving unit. If the input optical signal is not be inverted, the electrical switch is turned off to put the semiconductor laser into an unoscillating state. The semiconductor optical amplifier only carries out optical amplification without the mutual gain modulation. The transmission wavelength of the variable wavelength optical filter is matched with an input wavelength of the input optical signal and a noninverted optical signal is supplied to the optical receiving unit.