Abstract: A novel overlay networking method designed specifically to handle the large file transfers that constitute a large and growing portion of media-rich Internet traffic is disclosed. The proposed system and method uses large (e.g., 10 MB) packets or Media Frames (MF) and orderly concatenations of these frames into chains (MC) to achieve a considerable reduction in power consumption relative to current IP Internet routers. Transmission of each MC is scheduled, while individual MFs are routed directly in interstices within MCs.

Abstract: Disclosed are systems and methods for improving the performance of systems for generating and detecting electromagnetic radiation at terahertz (THz) frequencies. Embodiments of the systems and methods include the fabrication and use of coupling tapers to provide efficient transfer of THz radiation between a photomixer and a waveguide that supports a propagating THz mode. A representative system comprises of a photomixer to convert high-frequency components of an optical pump signal into corresponding electrical THz frequencies, a waveguide that supports a propagating THz mode, and a matching taper that effectively converts the highly localized currents generated by the photomixer to the mode supported by the waveguide.

Abstract: Embodiments of a photonic link having low residual carrier, for use in transmitting information between an electronic signal source and an electronic signal receiver is provided. The photonic link comprises a transmitter, which uses angle modulation, and two threshold optical frequency discriminators that are biased to provide large even-order distortion, an optical signal receiver and at least one transmission fiber to transmit complementary modulated signals between the transmitter and the optical signal receiver, whereby the optical signal receiver reconstructs the complementary modulated signals into the electronic information for acceptance by the electronic signal receiver. Exemplary methods of transmitting information are also provided.

Abstract: Embodiments of a photonic link having low residual carrier, for use in transmitting information between an electronic signal source and an electronic signal receiver are provided. One exemplary photonic link comprises a transmitter, which has two non-linear threshold electronic to optical converters that are biased to provide large even-order distortion, an optical signal receiver and at least one optical transmission path to transmit complementary modulated signals between the transmitter and the optical signal receiver, whereby the optical signal receiver reconstructs the complementary modulated signals into the electronic information for acceptance by the electronic signal receiver. Exemplary methods of transmitting information are also provided.

Abstract: A passive optical network is provided that spectrally slices optical signals transmitted in both upstream and downstream directions utilizing wavelength division multiplexing routing. The passive optical network preferably includes an incoherent signal source at both ends to provide signals that are spectrally sliced according to optical frequency. The downstream information may be transmitted in a conventional data format. The upstream transmissions may be segregated by subcarrier multiplexing, time scheduling or wavelength division multiplexing.

Abstract: A passive optical network architecture is disclosed for application in a local loop telephone environment. A local digital switch transmits an optical signal bearing information downstream over an optical fiber to the terminal equipment of a group of subscribers. This transmitted optical signal comprises light at a number of different wavelengths, i.e., it is a wavelength-division multiplexed signal, where each subscriber is associated with a particular wavelength of light. Each subscriber's terminal equipment detects that portion of the transmitted optical signal that exists at its assigned wavelength and thereby recovers the information sent by the local digital switch for that subscriber. However, a fraction of this detected optical signal is then remodulated by the subscriber's equipment with the subscriber's upstream information and returned to the local digital switch. As a result, no optical sources exist in the subscriber equipment in this optical network architecture.

Abstract: A communication network (e.g., a coax network or an optical fiber network) comprises a signal distribution network (e.g., fiber node FN) for transmitting communication signals downstream over a first communication path to a plurality of end user apparatuses connected thereto. At least one end user apparatus is arranged for sending the return signals downstream over at least part of the first communication path to a converter apparatus which collects the return signals and converts them to an upstream signal for transmission over a second separate communication path to the distribution unit.

Abstract: A cellular communication system provides dynamic allocation of hardware resources and frequency spectrum. The cellular system includes a server which dynamically controls the assignment of radio ports to a first and second group; each group shares hardware resources. Radio ports assigned to a first group may be reassigned by the server to a second radio port group in response to a predetermined condition, such as when the number of active users in the first group approaches the maximum user capacity of the first group. The transceiver hardware of each radio port is pooled on a group basis at the server location. This increases the user capacity of any radio port of a group to equal the total user capacity available at that group, as well as making more efficient use of transceiver resources.

Abstract: Communication between an upstream point, such as a TV-source headend followed by a fiber optic line, and a number of downstream points, such as coaxial cable connected subscriber locations, is achieved by wavelength or frequency demultiplexing a spectrum of downstream radio-frequency signals with a surface-acoustic-wave (SAW) demultiplexer-multiplexer and distributing the demultiplexed signals to the downstream points, for example through the cables.

Abstract: A method and apparatus for reducing noise in optical communication systems is effected by modulating or dithering the laser output frequency at a relatively low rate. The laser may be dithered by applying a low frequency sine wave either to the resistive heater in the phase control section or to the laser's active section directly. By dithering the laser at a low frequency and at a sufficiently high amplitude to cause large optical frequency excursions, the noise caused by multipath interference will decrease without substantially increasing negative dispersion effects.

Abstract: An amplitude-modulated vestigial-sideband, television channel sub-carrier multiplexed optical fiber transmission system includes a laser diode operating linearly throughout the desired range of multiplex frequencies. Such linear laser diode operation is accomplished by limiting leakage current within the laser diode to a very low level. The composite second-order distortion in the optical output signal from the laser diode is down typically 50 db from the video carrier for each channel. For some laser diodes that exhibit slow turn-on in the L-I characteristic, there is a point of inflection in the L-I curve. Operation with the laser biased at or near this point results in extremely linear performance, even though the laser may have insufficient blocking of leakage current to otherwise produce acceptable linearity.

Abstract: The present invention relates to a N.times.N single-mode optical coupler employing evanescent wave coupling between mutually adjacent optical waveguides sufficiently close to one another to facilitate coupling among all the waveguides. An optical signal of a narrow frequency band, e.g. appreciably less than 100 gigahertz, introduced to an input port of one of the waveguides is found to be nonuniformly distributed among the output ports of the coupler. A first embodiment uses the nonuniform distributions of narrowband optical signals to the output ports of the coupler to enable the present invention to be used as essentially a selective switching device. A second embodiment introduces one or more predetermined broadband optical signals to one or more input ports of the coupler to produce an appreciably uniform power distribution among the output ports of the coupler.

Abstract: The present invention relates to an optical upconverting or downconverting gain or loss modulating mixer and a receiver for subcarrier optical communication systems using this mixer. The optical mixer can be formed, for example, from an optical amplifier including a semiconductor laser chip comprising a p-n junction with an active region channel formed along the junction. An optical signal received from the communication system is directed into one end of the channel, and a combination of a D-C bias signal and a local oscillator signal is concurrently impressed on the chip to gain-modulate the received optical signal and produce an upconverted or downconverted output signal. In the receiver, the upconverted or downconverted output signal from the gain-modulated optical amplifier is detected by a photodetector, amplified if necessary, filtered and then demodulated before transmission to the output utilization device.

Abstract: The present invention relates to a switching technique for packet Frequency Division Multiplexed (FDM) communication systems. In the present system, each of N system users is assigned (a) either a separate fixed one of N transmit frequency channels or a selected free one of L transmit frequency channel for communications to a head-end FDM channel switching arrangement (IO), and (b) a fixed assigned separate one of N receive channels for communications from the head-end FDM channels switching arrangement. At the FDM channel switching means, all FDM channel signals received from the system users are directed into separate paths (21) through the switching arrangement. The signals in each path are demodulated (23) to baseband, and a destination address in each packet is detected (28) to determine where each packet is to be sent.

Abstract: The present invention relates to an optimized guided wave microwave or lightwave communication system or network wherein a plurality of directional couplers (14, 17) (a) are disposed along a bus-like wave guiding means (13, 16), and (b) include separate coupling coefficients which are optimized. More particularly, the present invention relates to a guided wave communication system or network including, for example, a head-end unit (15) which is coupled to one end of a bus-like wave guiding means. Separate directional couplers are disposed along the wave guiding means to couple lightwave or microwave signals either (a) into the bus-like wave guiding means (13) from separate transmitters (11), or (b) from a bus-like wave guiding means (16) to separate receivers (12).

Abstract: The present invention relates to an optical communication system wherein the entire microwave frequency bandwidth of the optical source-to-detector system is subdivided into a plurality of non-overlapping frequency bands or channels, and each user transmits and/or receives information either (a) on a separate fixed one of the channels, (b) on a free channel selectively assigned via control signals transmitted on a separate control channel at the time of initiation of a communication, or (c) on a channel randomly selected at the receiver by an associated user to receive a particular program. The present optical communication system can be configured to simultaneously broadcast multiple programs over separate channels for random selection by each user, or to achieve local and/or external two-way communications with the associated system users.