Abstract: An optical transceiver supports bidirectional communication with another optical transceiver that is a communications partner via a single-mode optical fiber. A surface emitting laser has a T-band oscillation wavelength that is shorter than the cutoff wavelength of the optical fiber. A photodetector has detection sensitivity with respect to the T band.

Abstract: An optical amplification device includes: a semiconductor optical amplifier; a first detector that detects an input optical power of the semiconductor optical amplifier; a second detector that detects an output optical power of the semiconductor optical amplifier; and a controller that controls a driving current of the semiconductor optical amplifier, wherein the controller supplies a predetermined driving current to the semiconductor optical amplifier when an optical signal is not input to the semiconductor optical amplifier, the second detector detects an optical power of Amplified Spontaneous Emission (ASE) output from the semiconductor optical amplifier when the predetermined driving current is supplied to the semiconductor optical amplifier, and the controller controls the driving current of the semiconductor optical amplifier based on the input optical power of the semiconductor optical amplifier detected by the first detector, and the optical power of the ASE.

Abstract: An optical amplification device includes: a semiconductor optical amplifier; a first detector that detects an input optical power of the semiconductor optical amplifier; a second detector that detects an output optical power of the semiconductor optical amplifier; and a controller that controls a driving current of the semiconductor optical amplifier, wherein the controller supplies a predetermined driving current to the semiconductor optical amplifier when an optical signal is not input to the semiconductor optical amplifier, the second detector detects an optical power of Amplified Spontaneous Emission (ASE) output from the semiconductor optical amplifier when the predetermined driving current is supplied to the semiconductor optical amplifier, and the controller controls the driving current of the semiconductor optical amplifier based on the input optical power of the semiconductor optical amplifier detected by the first detector, and the optical power of the ASE.

Abstract: An optical amplification device includes: a port group that has a plurality of ports that have a semiconductor optical amplifier and a port that does not have a semiconductor optical amplifier, an optical burst signal being input into each of the ports at a different timing; and a control unit, wherein: when an optical inputting into the port that has the semiconductor optical amplifier is detected, the control unit activates the semiconductor optical amplifier of the port where the optical inputting is detected, inactivates the other semiconductor optical amplifier and remains an activation until another optical inputting is detected in another semiconductor optical amplifier; and when an optical inputting into the port that does not have the semiconductor optical amplifier is detected, the control unit inactivates the semiconductor optical amplifiers of the plurality of the ports that have the semiconductor optical amplifier.

Abstract: An optical amplification device includes: a plurality of semiconductor optical amplifiers to which an optical burst signal is input at a different timing; an optical coupler that combines output signals output from the plurality of semiconductor optical amplifiers; a detection unit that detects an optical inputting to the plurality of semiconductor optical amplifiers; and a control unit that activates one of the semiconductor optical amplifiers where the optical inputting is detected, inactivates the other semiconductor optical amplifier, and remains the activation until another optical inputting is detected in the other semiconductor optical amplifier.

Abstract: An optical amplification device includes: a port group that has a plurality of ports that have a semiconductor optical amplifier and a port that does not have a semiconductor optical amplifier, an optical burst signal being input into each of the ports at a different timing; and a control unit, wherein: when an optical inputting into the port that has the semiconductor optical amplifier is detected, the control unit activates the semiconductor optical amplifier of the port where the optical inputting is detected, inactivates the other semiconductor optical amplifier and remains an activation until another optical inputting is detected in another semiconductor optical amplifier; and when an optical inputting into the port that does not have the semiconductor optical amplifier is detected, the control unit inactivates the semiconductor optical amplifiers of the plurality of the ports that have the semiconductor optical amplifier.

Abstract: An optical amplification apparatus includes a front-stage semiconductor optical amplifier which amplifies an input light and a rear-stage semiconductor optical amplifier which amplifies an amplified light outputted from the front-stage semiconductor optical amplifier. The front-stage semiconductor optical amplifier exercises auto level control of an output light by exercising variable control of driving current which flows according to applied voltage higher than light emitting threshold voltage of an internal optical amplification element. The rear-stage semiconductor optical amplifier performs gate switching of a transmitted light by exercising switching control of driving current. By doing so, distortion of a waveform is controlled and optical communication quality can be improved.

Abstract: An optical amplifier which amplifies a wavelength division multiplexed optical signal having a variable number of channels associated with different wavelengths and outputs the amplified WDM optical signal. The optical amplifier includes a first optical amplifier which amplifies the wavelength division multiplexed optical signal and outputs the first optical amplifier amplified wavelength division multiplexed optical signal; a variable optical attenuator which controls a level of the first optical amplifier amplified wavelength division multiplexed optical signal and outputs the controlled wavelength division multiplexed optical signal; a second optical amplifier which amplifies the controlled wavelength division multiplexed optical signal and outputs the amplified, controlled wavelength division multiplexed optical signal; and a controller which controls the wavelength division multiplexed optical signal to be amplified with a constant gain.

Abstract: An optical apparatus receives an upward signal light from a plurality of subscriber units, where the upward signal light is composed of a plurality of time slots corresponding to the plurality of optical subscriber units. The optical apparatus includes a driving unit configured to determine a respective required gain for light from each of the plurality of optical subscriber units, an amplifying section configured to amplify the upward signal light with the required gain corresponding to the time slots of the upward signal light, and a receiver configured to receive the amplified upward signal light.

Abstract: There is provided a repeater to relay an optical signal transmitted/received between an optical line terminal (OLT) and at least one optical network unit (ONU), the repeater including: a first port configured to receive an optical signal input from the at least one ONU; a converter circuit configured to convert an optical signal of a first transmission rate into an optical signal of a second transmission rate higher than the first transmission rate, the optical signal of the first transmission rate to be converted being included in optical signals received at the first port; and a second port configured to output the optical signal converted by the converter circuit to the OLT.

Abstract: An optical receiving device includes multiple input ports to which light is input; multiple amplifiers that are arrayed and provided corresponding to the input ports, respectively, each of the amplifiers amplifying and outputting light input from a corresponding input port among of the input ports; a photo diode that converts light into an electrical signal; and a lens that inputs to the photo diode light output from the amplifiers.

Abstract: An optical amplifying device includes an optical system including a first end and a second end, the optical system configured to receive signal light through the first end, to lead the received signal light to an optical amplifying medium, and to output the signal light amplified by the optical amplifying medium through the second end, the optical system including a first optical isolator and a second optical isolator which are arranged on respective sides of the optical amplifying medium, wherein with respect to a direction in which the signal light propagates, each of the first optical isolator and the second optical isolator is capable of allowing light propagating in the same direction to pass therethrough and blocking light propagating in the opposite direction, and the first optical isolator and the second optical isolator have different center isolation wavelengths for the light propagating in the opposite direction.

Abstract: A wind power generation system 10 of an embodiment includes a rotor 40 having a hub 41 and blades 42, a nacelle 31 pivotally supporting the rotor 40, a tower 30 supporting the nacelle 31, an airflow generation device 60 provided in a leading edge of each of the blades 42 and having a first electrode 61 and a second electrode 62 which are separated via a dielectric, and a discharge power supply 65 capable of applying a voltage between the electrodes of the airflow generation device 60. Further, the system includes a measurement device detecting information related to at least one of output in the wind power generation system 10, torque in the rotor 40 and a rotation speed of the blades 42, and a control unit 110 controlling the discharge power supply 65 based on an output from the measurement device.

Abstract: An optical amplification device includes: a plurality of semiconductor optical amplifiers to which an optical burst signal is input at a different timing; an optical coupler that combines output signals output from the plurality of semiconductor optical amplifiers; a detection unit that detects an optical inputting to the plurality of semiconductor optical amplifiers; and a control unit that activates one of the semiconductor optical amplifiers where the optical inputting is detected, inactivates the other semiconductor optical amplifier, and remains the activation until another optical inputting is detected in the other semiconductor optical amplifier.

Abstract: A multi-wavelength light amplifier includes a first-stage light amplifier which has a first light amplifying optical fiber amplifying a light input, a second stage light amplifier which has a second light amplifying optical fiber amplifying a first light output from the first-stage light amplifier, and an optical system which maintains a second light output of the second-stage light amplifier at a constant power level. The first-stage and second-stage light amplifiers have different gain vs wavelength characteristics so that the multi-wavelength light amplifier has no wavelength-dependence of a gain thereof.

Abstract: A wind power generation system 10 of an embodiment includes a rotor 40 having blades 42, an airflow generation device 60 provided in a leading edge of each of the blades 42 and having a first electrode 61 and a second electrode 62 which are separated via a dielectric, a discharge power supply 65 applying a voltage between the electrodes of the airflow generation device 60, and a control unit 110 controlling the discharge power supply 65. The control unit 110 controls the voltage to perform pulse modulation so that the value of a relational expression fC/U is 0.1 or larger and 9 or smaller where f is a pulse modulation frequency of the voltage, C is a chord length of the blades 42, and U is a relative velocity combining a peripheral velocity of the blades 42 and a wind velocity, so as to generate plasma induced flow.

Abstract: An optical amplifier which amplifies a wavelength division multiplexed optical signal having a variable number of channels associated with different wavelengths and outputs the amplified WDM optical signal. The optical amplifier includes a first optical amplifier which amplifies the wavelength division multiplexed optical signal and outputs the first optical amplifier amplified wavelength division multiplexed optical signal; a variable optical attenuator which controls a level of the first optical amplifier amplified wavelength division multiplexed optical signal and outputs the controlled wavelength division multiplexed optical signal; a second optical amplifier which amplifies the controlled wavelength division multiplexed optical signal and outputs the amplified, controlled wavelength division multiplexed optical signal; and a controller which controls the wavelength division multiplexed optical signal to be amplified with a constant gain.

Abstract: There is provided a terminal apparatus including a message monitor to gather transmission request information from each of first and second terminating apparatus, a dynamic bandwidth allocation unit to allocate each transmission band in accordance with the gathered transmission request information, determine a size and an alignment position of a time slot in accordance with the allocated transmission band, determine a transmission start time of the time slot, and allocate an extinction period so as to stop a transmission of an optical signal between a time slot of the optical signal with the second transmission rate and a time slot following the time slot of the optical signal with the second transmission rate, and a MAC controller to generate a control frame for notifying each of the first and second terminating apparatus of the transmission start time and the size of the time slot.

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by ?, the controller controls a level of the light received by the second optical amplifier to change by approximately ??. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.