| 摘要 |
PURPOSE:To reduce electric power consumption by providing a refractive index varying means which independently varies the refractive indices of branch waveguides and controlling the refractive index of the branch waveguide corresponding to a certain optical amplifier which is in an excitation state to the refractive index higher than the refractive index of the other branch waveguide. CONSTITUTION:The refractive index of the branch waveguide 2 corresponding to the optical amplifier 3 which is in the excitation state is so controlled as to be higher than the refractive index of the other branch waveguide 2. The means which utilizes an electro-optic effect or thermooptical effect by mounting an optical amplifier to the branch waveguide 2 is used as the refractive index varying means. Namely, the light advancing in a main waveguide is guided to the branch waveguide of the high refractive index if there are the branch waveguide of the high refractive index and the branch waveguide of the low refractive index in the branch part. The guided light is, therefore, guided efficiently to the optical amplifier which is in the excitation state. The reduction by half of the photoelectric power inputted to the optical amplifier which is in the excitation state is thereby obviated and, therefore, the amplification factor of the optical amplifier can be set correspondingly lower and the electric power consumption is reduced. |
