Abstract: An optical transmitter includes an optical modulator, a tunable optical filter, a temperature sensor, and a processor. The tunable optical filter is provided on an output side of the optical modulator and transmits light of a frequency corresponding to a control voltage. The temperature sensor detects a temperature around the tunable optical filter. The processor detects an optical loss occurring in the tunable optical filter, calculates a width of a range of the control voltage in which the detected optical loss is smaller than a specified threshold, adjusts the control voltage based on the temperature detected by the temperature sensor, and shifts the control voltage by a specified amount that is larger than zero and smaller than or equal to a half of the calculated width of the range when the optical loss is larger than or equal to the threshold.

Abstract: An optical transmission device includes: a first drive unit that drives a VOA adjusting an attenuation amount for an optical signal from an optical amplifier; a second drive unit that drives an excitation light source of the optical amplifier; a first FF control unit that sets a first set value for the first drive unit and performs FF control; a second FF control unit that sets a second set value for the second drive unit and performs the FF control; a first control unit that controls the second drive unit in a manner that causes an optical output power from the optical amplifier to attain a first control target value; and a switch unit that switches to the first control unit when the optical output power corresponding to the second set value is attained as a result of FF control of the second FF control unit.

Abstract: An optical transmission device includes: a first drive unit that drives a VOA adjusting an attenuation amount for an optical signal from an optical amplifier; a second drive unit that drives an excitation light source of the optical amplifier; a first FF control unit that sets a first set value for the first drive unit and performs FF control; a second FF control unit that sets a second set value for the second drive unit and performs the FF control; a first control unit that controls the second drive unit in a manner that causes an optical output power from the optical amplifier to attain a first control target value; and a switch unit that switches to the first control unit when the optical output power corresponding to the second set value is attained as a result of FF control of the second FF control unit.

Abstract: A coherent optical receiver includes: an attenuator that adjusts a power of an input optical signal; a mixer that mixes an optical signal output from the attenuator and local oscillator light; a photo detector that converts an optical signal output from the mixer into an electric signal; an amplifier that amplifies an output signal of the photo detector; a gain controller that controls a gain of the amplifier; a memory that stores dependence information that indicates a relation between an input optical power of an optical signal of a specified wavelength and a gain of the amplifier; and a controller that calculates an input optical power of the target wavelength based on a gain of the amplifier and the dependence information, and controls an attenuation amount of the attenuator based on the calculated input optical power, when a WDM optical signal is input into the coherent optical receiver.

Abstract: According to an aspect of the embodiment provides a communication terminal for communicating in a network. The terminal receives from another communication terminal a request includes an obscured call information for obscuring an identification information. The communication terminal obscures the identification information after receiving the request.

Abstract: According to an aspect of the embodiment provides a communication terminal for communicating in a network. The terminal receives from another communication terminal a request includes an obscured call information for obscuring an identification information. The communication terminal obscures the identification information after receiving the request.

Abstract: Upon receiving a selection of a name of a member of a desired reception destination by an input through a button operation, the caller's mobile terminal apparatus transmits a hiding-number outgoing-call request including a caller's phone number and a phone-number hiding flag to a receiver's phone number. The receiver's mobile terminal apparatus acquires, when the phone-number hiding flag is included in the received hiding-number outgoing-call request, a name corresponding to the caller's phone number, displays an incoming-call screen with acquired name on a display unit.