Abstract: A high-speed optical amplifier is considered to be an important optical device because of an increasing demand of routing, which is accompanied by an increase in complexity of networks. It is difficult to satisfy a response performance by related-art techniques, and there has been a problem in achieving a high-speed response performance of 10 microseconds or less. An optical amplifier according to the present invention includes: an input monitor means 500; an optical amplification means 310 including an optical amplification medium 300, and a control means 400 for performing feed-forward control. When the optical amplification means is controlled by the feed-forward control in response to a signal of the input monitor means 500, an overshoot signal is applied as a control signal so that a slow response performance specific to the optical amplification medium has been improved, and thereby high-speed response performance has been achieved.

Abstract: The present invention relates to an optical receiver, and particularly, to an optical receiver by which a DQPSK-modulated optical signal is demodulated to a multilevel phase-modulated signal.

Abstract: A high-speed optical amplifier is considered to be an important optical device because of an increasing demand of routing, which is accompanied by an increase in complexity of networks. It is difficult to satisfy a response performance by related-art techniques, and there has been a problem in achieving a high-speed response performance of 10 microseconds or less. An optical amplifier according to the present invention includes: an input monitor means 500; an optical amplification means 310 including an optical amplification medium 300, and a control means 400 for performing feed-forward control. When the optical amplification means is controlled by the feed-forward control in response to a signal of the input monitor means 500, an overshoot signal is applied as a control signal so that a slow response performance specific to the optical amplification medium has been improved, and thereby high-speed response performance has been achieved.