Abstract: An excitation light source apparatus includes: an excitation light source to generate Raman excitation light in a drive state and to stop generating the Raman excitation light in a stop state; a light source controller to control the intensity of the Raman excitation light in the drive state; a light level measuring instrument to measure the light level of signal light; a logarithmic converter to convert at least one measurement result of measuring by the light level measuring instrument to a logarithmic value; and a main controller to decide a correction value based on the logarithmic value of the at least one measurement result in the stop state. The main controller controls the light source controller by using the correction value and a preset gain control target value.

Abstract: A signal light interruption detection device includes an optical interleaver to demultiplex wavelength-multiplexed light into light in first frequency ranges corresponding to a first frequency grid including frequencies at regular frequency intervals in which a main signal light component can be arranged and light in second frequency ranges corresponding to a second frequency grid shifted from the first frequency grid by a half cycle of the regular frequency intervals, a first optical detector to detect first light power as total power of the light in the first frequency ranges, a second optical detector to detect second light power as total power of the light in the second frequency ranges, and a judgment unit to output a notification signal based on a difference between the first light power detected by the first optical detector and the second light power detected by the second optical detector.

Abstract: An optical transmission line switching apparatus relays main signal light input via a main transmission line including at least two transmission lines. When no failure occurs in the main transmission line, a control unit controls an optical switch and an optical switch so that the optical switch and the optical switch are connected to different transmission lines. When a failure occurs in one of the at least two transmission lines, the control unit controls the optical switch and the optical switch so that the optical switch and the optical switch are connected to a transmission line that does not have the failure. When recovery from the failure is completed, the control unit controls the optical switch and the optical switch so that the optical switch and the optical switch are connected to different transmission lines.

Abstract: An optical transmission line switching apparatus relays main signal light input via a main transmission line including at least two transmission lines. When no failure occurs in the main transmission line, a control unit controls an optical switch and an optical switch so that the optical switch and the optical switch are connected to different transmission lines. When a failure occurs in one of the at least two transmission lines, the control unit controls the optical switch and the optical switch so that the optical switch and the optical switch are connected to a transmission line that does not have the failure. When recovery from the failure is completed, the control unit controls the optical switch and the optical switch so that the optical switch and the optical switch are connected to different transmission lines.

Abstract: An excitation light source apparatus includes: an excitation light source to generate Raman excitation light in a drive state and to stop generating the Raman excitation light in a stop state; a light source controller to control the intensity of the Raman excitation light in the drive state; a light level measuring instrument to measure the light level of signal light; a logarithmic converter to convert at least one measurement result of measuring by the light level measuring instrument to a logarithmic value; and a main controller to decide a correction value based on the logarithmic value of the at least one measurement result in the stop state. The main controller controls the light source controller by using the correction value and a preset gain control target value.

Abstract: A signal light interruption detection device includes an optical interleaver to demultiplex wavelength-multiplexed light into light in first frequency ranges corresponding to a first frequency grid including frequencies at regular frequency intervals in which a main signal light component can be arranged and light in second frequency ranges corresponding to a second frequency grid shifted from the first frequency grid by a half cycle of the regular frequency intervals, a first optical detector to detect first light power as total power of the light in the first frequency ranges, a second optical detector to detect second light power as total power of the light in the second frequency ranges, and a judgment unit to output a notification signal based on a difference between the first light power detected by the first optical detector and the second light power detected by the second optical detector.

Abstract: An excitation light source device includes: an excitation light source to generate the Raman excitation light; a light source controller to control an intensity of the Raman excitation light; an amplified spontaneous emission noise measurer to measure an intensity of amplified spontaneous emission noise caused by the Raman excitation light; and a transmission line abnormality analyzer to detect abnormality in the transmission line on a basis of a control state of the light source controller and a measurement result of the amplified spontaneous emission noise measurer. In a state where the abnormality is not detected, the light source controller controls the intensity of the Raman excitation light to gradually increase to a set value. In a state where the abnormality is detected, the light source controller controls the excitation light source to stop or reduce generation of the Raman excitation light.

Abstract: An excitation light source device includes: an excitation light source to generate the Raman excitation light; a light source controller to control an intensity of the Raman excitation light; an amplified spontaneous emission noise measurer to measure an intensity of amplified spontaneous emission noise caused by the Raman excitation light; and a transmission line abnormality analyzer to detect abnormality in the transmission line on a basis of a control state of the light source controller and a measurement result of the amplified spontaneous emission noise measurer. In a state where the abnormality is not detected, the light source controller controls the intensity of the Raman excitation light to gradually increase to a set value. In a state where the abnormality is detected, the light source controller controls the excitation light source to stop or reduce generation of the Raman excitation light.

Abstract: An input buffer circuit without a drop of a capability of a circuit and a limitation of a connection type with a circuit of a former stage is obtained. The output signal (OUTB) is inputted to a first low pass filter circuit, and the first low pass filter circuit integrates the output signal (OUTB). A result of the integration is stored as a voltage value (V2a) in the capacitor (4s). In the same manner, an output signal (OUT) is inputted to a second low pass filter circuit, and the second low pass filter circuit integrates the output signal (OUT). A result of the integration is stored as a voltage value (V2b) in a capacitor (4t). A differential amplifier circuit (5) generates appropriate voltages (V3a and V3b) according to a design specification of the transistors (1x and 1y) by amplifying the voltage values (V2a and V2b) and outputs them. The voltages (V3a and V3b) are impressed on respective back gates of the transistors (1x and 1y), respectively.

Abstract: An input buffer circuit without a drop of a capability of a circuit and a limitation of a connection type with a circuit of a former stage is obtained. The output signal (OUTB) is inputted to a first low pass filter circuit, and the first low pass filter circuit integrates the output signal (OUTB). A result of the integration is stored as a voltage value (V2a) in the capacitor (4s). In the same manner, an output signal (OUT) is inputted to a second low pass filter circuit, and the second low pass filter circuit integrates the output signal (OUT). A result of the integration is stored as a voltage value (V2b) in a capacitor (4t). A differential amplifier circuit (5) generates appropriate voltages (V3a and V3b) according to a design specification of the transistors (1x and 1y) by amplifying the voltage values (V2a and V2b) and outputs them. The voltages (V3a and V3b) are impressed on respective back gates of the transistors (1x and 1y), respectively.