摘要 |
<p>An optical receiver is disclosed in which a portion of the electric signal produced by optical-to-electric conversion is coupled out and fed to an automatic control system (4, 5, 8, 9, 12-17). The automatic control system contains polarization control elements (4, 5) which control the polarization of the received light beam relative to that produced by the local oscillator so that the electric output signal is maximized. There is no requirement for either light beam to be polarized in a particular direction in order to have optimum matching.</p> |