Patent ID: 7616318

Claim:
An optical electric field waveform observing apparatus, comprising: a measuring unit which measures through sampling with respect to time an optical electric field of an input optical signal digitally modulated, for each set of an in-phase component and a quadrature component or each set of an amplitude component and a phase angle component; an measuring unit which measures by use of optical homodyne interference optical electric field components of an input light digitally modulated using a symbol pattern with a fixed repetitive period; and a controlling unit which controls a phase difference between two optical paths of a homodyne interferometer or an optical phase of an optical source, the apparatus further comprising either one of: a conducting unit which conducts three-dimensional display of a three-dimensional optical electric field waveform in which two optical electric field components are arranged in a time series; and a synthesizing unit which synthesizes a three-dimensional optical electric field eye pattern in which two optical electric field components are folded in a time series direction in a time unit which is an integral multiple of one-bit time or one-symbol time of digital modulation and conducting three-dimensional display of a three-dimensional eye pattern.