Patent ID: 8873968
Filing Date: 2014-10-28
Classification: H04B,H04L

Abstract:
1. An optical field receiver for receiving an optical multilevel signal, the optical field receiver comprising: an optical branching circuit for branching a received optical multilevel signal into first and second optical signals; a first optical delayed demodulator for performing delayed demodulation on the first optical signal at a delay time T to output a delayed demodulation signal representing x component of a complex signal, where T is symbol time of the optical multilevel signal; a second optical delayed demodulator for performing delayed demodulation on the second optical signal at the delay time T with an optical phase difference deviating from the first optical delayed demodulator by 90° to output a delayed demodulation signal representing y component of the complex signal; first and second optical receivers for converting the delayed demodulation signals output from the first and second delayed demodulators into first and second electrical signals, respectively; an optical field processing unit using the first and second electrical signals as input for generating a first reconstructed signal and a second reconstructed signal, the first reconstructed signal being generated using and hence representing a value of an inter-symbol optical carrier phase difference from a symbol before 1 symbol time including transmitted data information based on the first and second electrical signals for each symbol time T, the second reconstructed signal being generated using and hence representing an amplitude value of the received symbol based on the first and second electrical signals for each symbol time T; and a symbol decision circuit for decoding a multilevel digital signal corresponding to the received symbol on the basis of the first reconstructed signal and the second reconstructed signal output from the optical field processing unit.