[Problem] To provide a system for estimating the power–optical response imbalance between an in-phase (I) channel and a quadrature-phase (Q) channel of an optical quadrature amplitude modulator (optical IQ modulator), using a simple device. [Solution] A system for estimating the power–optical response imbalance between an I channel and a Q channel of an optical IQ modulator, that has a photodetector (PD), an analog–digital converter (ADC) and an imbalance calculation unit that: estimates the power–optical response imbalance between an I channel and a Q channel of an optical quadrature amplitude modulator (optical IQ modulator); has an input signal information reception unit that receives information pertaining to a first modulation signal and a strength information reception unit that receives strength information for digitized output signals from the ADC; and uses the information pertaining to the first modulation signal and the strength information from the digitized output signal and estimates the power–optical response imbalance between the I channel and the Q channel.
TECHNOLOGY FOR OPTICAL MODULATOR EVALUATION ON BASIS OF PHASE RECOVERY