A transducer for use in a hybrid optical and radio communications system includes a zero electrical power photodetector and a radio antenna. The photodetector is electrically connected to the radio antenna so that, in use, optical signals are received and radio signals are transmitted by the transducer without the use of electrical power. The transducer can thus be remotely sited at locations in communications systems not having a supply of electrical power. In a first embodiment the photodetector includes a zero-bias photodiode, and in a second embodiment the transducer includes a self-biasing photodetector.
The present invention allows remote antenna units for radio frequency signal transmission and receipt to operate without the requirement for remote electrical power supplies or for connecting cables that incorporate electrical conductors. According to an aspect of the present invention, an optical communications system employing radio frequency signals comprises a central unit; at least one remote unit having at least one optoelectronic transducer for converting optical data signals to radio frequency signals and converting radio signals to optical signals and at least one antenna to receive and send radio frequency signals; at least one optical fiber data link between the central unit and the remote unit for transmitting optical data signals therebetween; and at least one optical fiber power link between the central unit and the remote unit for providing electrical power at the remote unit.
An optical communications network includes a terminal which can simultaneously receive and modulate an optical signal. The terminal includes an optical modulator which is controlled by varying the bias voltage applied to it.
An optical communications network includes a terminal which can simultaneously receive and modulate an optical signal. The terminal includes an optical modulator which is controlled by varying the bias voltage applied to it.
A photodiode with a semiconductor intrinsic light absorption layer has at least one p-doped light absorption layer or an n-doped light absorption layer, and preferably both. The diode also has a cathode electrode and an anode electrode electrically coupled with the p-doped light absorption layer or the n-doped light absorption layer.
A system and method are described for integrating a fiber optic fixed access network and a fiber optic radio access network. At least one radio unit transmits and receives communications with at least one mobile unit. A first multiplexer transmits and receives the communications with the at least one radio unit and fixed access communications with at least one fixed access subscriber. The first multiplexer is connected to each of the at least one radio unit and to each of the at least one fixed access subscriber using fiber optic connections. Each of the at least one radio unit transmits and receives the communications with the first multiplexer using a wavelength that is different for each of the at least one radio unit and different from that used to transmit and receive the fixed access communications from the at least one fixed access subscriber. The communications and the fixed access communications are transmitted and received together between the first multiplexer and a second multiplexer through the fiber optic fixed access network using the different wavelengths.
