Patent ID: 7417792

Claim:
An optical amplification device comprising: an automatic gain controller configured to perform automatic gain control in accordance with a control coefficient; and an adjusting unit configured to determine whether a current state is a first state or a second state by comparing magnitude of at least one of a measured power of input light to the optical amplification device and measured power of output light from the optical amplification device to a predetermined value, and changing the control coefficient in accordance with the determined current state, wherein the first state is a state in which a number of frequencies included in the input light is being increased or decreased, and the second state is a state in which the number of frequencies included in the input light is not being adjusted, the adjusting unit is configured to determine whether a transition occurred from the first state to the second state, or whether a transition occurred from the second state to the first state, to thereby determine the current state, and a predetermined range used for determining a transition from the first state to the second state is different from a predetermined range used for determining a transition from the second state to the first state.