Optical transmission apparatus and method for controlling optical power
An optical transmission apparatus includes: an optical receiver configured to receive an optical signal; a variable optical attenuator configured to adjust a power of the optical signal to be input to the optical receiver according to a variable attenuation amount; and a controller configured to control the attenuation amount of the variable optical attenuator based on an electrical signal obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver.
1. An optical transmission apparatus comprising:
an optical receiver configured to receive an optical signal;
a variable optical attenuator configured to adjust a power of the optical signal to be input to the optical receiver according to a variable attenuation amount;
a monitor configured to monitor a power of the optical signal to be input to the variable optical attenuator;
a gain amplifier configured to amplify an electrical signal according to a variable gain subjected to an automatic gain control, the electric signal being obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver; and
a controller configured to control the attenuation amount of the variable optical attenuator based on the variable gain of the gain amplifier, a value of the power monitored by the monitor, and a peak indicator of the automatic gain control.
2. The optical transmission apparatus according to claim 1 ,
wherein the controller, based on the gain and the monitored value,
controls the attenuation amount so that the monitored value reaches between an upper limit and a lower limit of a reception range of the optical receiver, and
controls the attenuation amount so that a difference between the gain and a control target value of the gain becomes smaller.
3. The optical transmission apparatus according to claim 1 ,
wherein the controller controls the attenuation amount based on the gain so that an output amplitude of the gain amplifier becomes constant.
4. The optical transmission apparatus according to claim 3 ,
wherein the controller
controls the attenuation amount so that a difference between the output amplitude and a target value of the output amplitude becomes smaller, and
controls the attenuation amount so that a difference between the gain and a target value of the gain becomes smaller.
5. The optical transmission apparatus according to claim 1 ,
wherein the optical receiver includes
a photodetector configured to photoelectrically convert the optical signal received by the optical receiver, and
a transimpedance amplifier configured to convert a current signal obtained by the photodetector into a voltage signal and to amplify the voltage signal, and
wherein the controller controls the attenuation amount based on an output amplitude of the transimpedance amplifier.
6. A method for controlling an optical power, the method comprising:
receiving, by an optical receiver, an optical signal;
adjusting, by a variable optical attenuator, a power of the optical signal to be input to the optical receiver according to a variable attenuation amount;
monitoring a power of the optical signal to be input to the variable optical attenuator;
amplifying an electrical signal according to a variable gain subjected to an automatic gain control, the electric signal being obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver; and
controlling the attenuation amount based on the variable gain, a value of the monitored power, and a peak indicator of the automatic gain control.