Patent ID: 8184992

Claim:
An optical field receiver for receiving an optical signal modulated with an information signal of symbol rate R, comprising: an optical brancher for branching the received optical signal into first and second optical signals; an optical delayed detector for performing delayed detection on the first optical signal at a delay time Td and shifting a phase of the first optical signal by +90° or −90°; a first optical receiver for receiving the first optical signal output from the optical delayed detector and converting the first optical signal into a first electrical signal; a second optical receiver for receiving the second optical signal and converting the second optical signal into a second electrical signal; and an operation circuit for calculating the amplitude and phase of optical field of the received optical signal or in-phase component and quadrature component of the optical field, from the first and second electrical signals, wherein a delay time Td of the optical delayed detector is Td≧1/(5R), and a propagation time difference of the first and second optical signals from the optical brancher to the operation circuit is equal to or less than the delay time Td.