| 摘要 |
In a manner analogous to electrical heterodyne reception, it is possible to construct an optical heterodyne receiver in which coherent received light is heterodyned with the light generated in a local laser and fed to a downstream photoelectric transducer. To date, it has been assumed with regard to the heterodyning that the polarisation of the heterodyned light and of the received light are at least approximately in agreement, so that there is a need for automatic control of polarisation. According to the invention, circularly polarised light is heterodyned, so that it is possible to eliminate polarisation controls. <IMAGE> |
