PURPOSE: To exclude the effect of a near end crosstalk by inserting two independent optical switches to an optical fiber.

CONSTITUTION: Data fetch switches SWr1, SWr2 are provided to the stage earlier than the stage of an active side guide path GI, a standby side waveguide G2 and data transmission switches SWs1, SWs2 are provided. Moreover, the data fetch switches SWr1, SWr2 are connected to reception sections OR1, OR2 by waveguides G3, G4 and an optical switch SW4 is inserted inbetween. The data transmission switches SWs1, SWs2 are connected to transmission sections OS1, OS2 by wave guides G5, G6 and an optical switch SW1 is inserted inbetween. The guide paths G5, G4 at the transmission side are crossed to the waveguides G3, G4 at the reception side at cross parts x1, x2 but the crosstalk is decreased easily to -40dB or below by selecting a cross angle θ to be sufficiently larger.