Abstract: A coherent optical receiver having an analog electrical circuit connected to combine the outputs of multiple photodetectors to generate an electrical output signal from which the data encoded in a received modulated optical signal can be recovered in a robust and straightforward manner. In an example embodiment, the analog electrical circuit includes one or more transimpedance amplifiers connected between the photodetectors and the receiver's output port. The coherent optical receiver may include a dual-polarization optical hybrid coupled to eight photodiodes to enable polarization-insensitive detection of the received modulated optical signal. The signal processing implemented in the analog electrical circuit advantageously enables the use of relatively inexpensive local-oscillator sources that may have relaxed specifications with respect to linewidth and wavelength stability.

Abstract: In one example embodiment, a communication system includes a remote unit configured to convert a plurality of signals, received at the remote unit from a plurality of end devices, into a plurality of first digital signals regardless of a bandwidth occupied by any of the plurality of signals. The communication system further includes a central unit configured to generate a plurality of second digital signals by processing the plurality of first digital signals received from the remote unit and transmit the plurality of second digital signals back to the remote unit, to be transmitted to the plurality of end devices.