PURPOSE: To switch an optical path only by the intra-office operation by switching the optical path by means of an optical coupler, optical multiplexer and demultiplexer and optical switch.
CONSTITUTION: An optical base line 2 and an optical link 6 are connected to the optical multiplexer and demultiplexer 7 and a current transformer O/E which converts a light signal to an electric signal is connected to the optical multiplexer and demultiplexer 7. The multiplexer and demultiplexer 7 which reflects the light of wavelengths λ1, λ3 and allows the transmission of the light of a wavelength λ2 is used. The wavelengths λ3 and λ1 may be equal or may be not equal if the O/E has the sensitivity to the light of the wavelength λ1, λ3. The optical coupler 8 may be multiplexer if λ3 and λ1 are not equal. The optical switch is not shown in the figure. The optical path is switched by said optical switch, the optical coupler 8 and the optical multiplexer and demultiplexer 7. The switching of the modes shown by arrows A, B, C is thereby executed with the switch board and in the office.
NIIJIMA MASAYUKI
KOKAYU MIKIO
