| 摘要 |
PURPOSE: To obtain a truly polarization independent coherent light wave detection system which necessitates only the minimum detecting elements by using an optical hybrid device having a single polarization beam divider and three polarization maintaining couplers in a set. CONSTITUTION: A reception message signal ES(t) is added to a polarization beam divider 12, and a pair of orthogonal components EH and EV is formed. A local oscillation signal EL0 (t) is added to a polarization maintaining coupler 22, and the output is divided into a pair of almost equal power components EL01 and EL02 . The components from each signal are added to one of polarization couplers 16 and 20. Those couplers 16 and 20 provide four mixed signals in a set constituted of two signals in each polarization state as the output of a hybrid device 11. It is desirable that optical waveguide parts 14, 18, 24, and 26 mutually connecting each coupler are polarization maintaining waveguide parts. The output of the device 11 is added to a receiving part 13, optic/electric conversion is operated, this electric signal is demodulated, and a message signal is restored. |
