A hybrid wireless optical and radio frequency (RF) communication link utilizes parallel free-space optical and RF paths for transmitting data and control and status information. The optical link provides the primary path for the data, and the RF link provides a concurrent or backup path for the network data, as well as a reliable and primary path for the control and status information. When atmospheric conditions degrade the optical link to the point at which optical data transmission fails, the hybrid communication link switches to the RF link to maintain availability of data communications. The switch may occur automatically, based on an assessment of the quality of the optical signal communicated through the optical path.

Hybrid wireless optical and radio frequency communication link

A method for generating a large number of stable microwave frequency components for wideband lightwave distribution networks is shown. A single oscillator (10) is used at a transmitter to provide all of the required subcarriers. The subcarriers are modulated by high data rate channels and then multiplexed for transmission over a fiber optic line. At a receiver, all of the tuning frequencies required for channel selection are generated by a single oscillator (10).

Microwave subcarrier generation for fiber optic systems

A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Method for operating a display panel with electrically-controlled waveguide-routing

An optical line terminal, a passive optical network and a radio frequency signal transmission method in the communication technical field are provided. The passive optical network comprises: OLT, ODN and at least one ONU. The OLT comprises: at least one transmitting unit, which provides one dedicated downlink optical carrier and two dedicated uplink optical carriers for ONU, the downlink radio frequency signal which needs to be transmitted to ONU is modulated on the dedicated downlink optical carrier for the ONU, and after combining the modulated downlink optical carrier and the two dedicated uplink optical carriers, the downlink optical signals are outputted; the two dedicated optical carriers for ONU are configured to bear ONU uplink radio frequency signals; a multiplexing/demultiplexing unit which multiplexes through wavelength division the downlink optical signal outputted from each transmitting unit and transmit it to ONU via ODN, and demultiplexes through wavelength division the uplink optical wave of each ONU which has been multiplexed through wavelength division and is transmitted by ODN, and then output them; and at least one receiving unit which obtains the uplink signal from the demultiplexed uplink optical signal. The bandwidth of wireless access network is enhanced, and the design of ONU is simple.

Optical line terminal, passive optical network and radio frequency signal transmission method

The present invention relates to methods and apparatus for wavelength division multiplexing (WDM) using arrays of optical filtering elements to create a desired wavelength passband in an optical filter. In one aspect of the invention, an optical demultiplexer is formed using an input waveguide, such as a planar waveguide or an optical fiber, coupled to plural output waveguides. Each output waveguide includes a wavelength selective configuration of optical filtering elements formed within a contiguous portion of the waveguide forming an optical channel-selective filter having spectral regions having an optical transmission passband and spectral regions of low transmissivity. Exemplary optical filtering elements are Bragg gratings formed into an optical filter which transmits a characteristic wavelength band.

Wavelength division optical multiplexing elements.

The method and associated system for providing increased information carrying capacity in optical fiber communication through frequency-division-multiplexing, comprising the steps of generating a reference optical beam, generating a plurality of closely spaced optical carriers having frequencies which are coherently related to the reference frequency of the reference optical beam and which are capable of drifting with the reference frequency while maintaining coherence therewith, and combining the plurality of closely spaced optical carriers to provide a multiplexed optical output beam. Advantageously, a frequency tracking optical beam tracks the reference optical beam and the plurality of closely spaced optical carriers of the multiplexed optical output beam are optically heterodyne detected by the tracking optical beam to convert the plurality of closely spaced optical carriers into a microwave spectrum, so that the individual carrier frequencies present in the microwave spectrum which correspond to the frequencies of the plurality of closely spaced optical carriers may be electronically heterodyne detected and separated from the microwave spectrum.

Coherent optical fiber communication with frequency-division-multiplexing

A method and associated system for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing, comprising the steps of generating a plurality of closely spaced optical carrier wave pairs with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another, assigning each of the plurality of optical carrier wave pairs to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.

Optical fiber communication for local area networks with frequency-division-multiplexing

A system is disclosed for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing. A plurality of closely spaced optical carrier wave pairs is generated with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another. Each of the plurality of optical carrier wave pairs is assigned to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.

Charles Kuen Kao

Papers

Coherent optical fiber communication with frequency-division-multiplexing

Optical fiber communication for local area networks with frequency-division-multiplexing

Optical fiber communication with frequency-division-multiplexing

Optical fiber for local area networks with frequency-division-multiplexing

Optical lan system