669 results about "Fiber optic transmission" patented technology

A full service cable television system and method are provided. The system comprises a cable headend, at least one fiber transport, at least one distribution hub, at least one hybrid fiber coax plant, and a plurality of set-top terminals. The system delivers television programs, advanced cable services, and online services. Programs and services are transmitted to the set-top terminals in both digital and analog formats to maintain downward compatibility with existing systems. The set-top terminal includes a central processing unit, a unified memory architecture, a memory management unit, communications circuitry, I/O control circuitry, and audio and video output circuitry. Through these components, the set-top terminal provides advanced cable services such as a comprehensive channel navigator, an interactive program guide, impulse Pay-Per-View, Near-Video-On-Demand and Video-On-Demand programming, and advanced configuration controls. The set-top terminal also provides online services such as World Wide Web browsing, Internet e-mail, and home shopping.

The system includes, at least first and second antennas receiving first and second radio frequency signals, and a multiplexing system converting the first and second radio frequency signals to first and second optical signals and multiplexing the first and second optical signals for transmission over the optical fiber. A central processing base station is adapted for connection to the optical fiber. The central processing base station demultiplexes the first and second optical signals from the optical fiber, converts the first and second optical signals into the first and second radio frequency signals, and processes the first and second radio frequency signals to obtain information signals. In another embodiment, a conductor such as a coaxial cable replaces the optical fiber, and the multiplexer multiplexes the first and second radio frequency signals onto the conductor. In a further embodiment, the central processing base station uses the same techniques to send signals to an access point for transmission.

A hybrid cable comprising an optical fiber, an intermediate layer surrounding the optical fiber, and an electrically insulating jacket surrounding the intermediate layer. The intermediate layers include a collection of metallic strands. The hybrid cable may be used to establish simultaneous electrical and fiber-optic connection between two communication devices. Thus, the two communication devices may simultaneously transfer optical signals through the optical fiber and perform any of various electrical functions (power transfer, eye safety control) through the metallic strands. For example, an optical transceiver may couple to an optical antenna unit through the hybrid cable. Such an optical transceiver may serve as part of a point-to-point link, a point-to-multipoint link, and/or, a link between a primary transceiver unit and an optical router.

This invention generally relates to an optical filter for a fiber optic communication system. A coupled multi-cavity optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

Disclosed by the present invention is a system and method for optical fiber transmission. The switching portion of the present invention adopts the single-layered integrated switching technology so as to ensure a relatively simple and easy maintenance compared with the switching in a traditional communication network where said switching is made in the service network layer and the bearer network layer, respectively. Moreover, the present invention implements data transmission via optical fiber throughout the entire telecommunication system such that demands for bandwidth resources are satisfied during the whole data transmission process and the QoS (Quality of Service) of different services as well as rapid and un-blocking switching of the services are ensured in the telecommunication system. Therefore, the present invention can implement on-demand allocation of bandwidth resources, enhancing the flexibility in network resource management while a subscriber can apply for bandwidth resources based on its demand, which satisfies the individual needs of the user.

An improved fiber-optic communications system comprises a multi-mode waveguide carrying an optical signal, a single-mode waveguide optically coupled to and receiving the optical signal from the multi-mode waveguide and an adiabatic coupler optically coupled between the multi-mode waveguide and the single-mode waveguide. The multi-mode and single-mode waveguides may be optical fibers. The adiabatic coupler may comprise a tapered core surrounded by a cladding. Alternatively, the adiabatic coupler may comprise a core surrounded by a cladding, wherein the refractive index of at least one of the core and the cladding varies over the length of the adiabatic coupler.

In a data processing system of the type having multiple processor units coupled to one another by a bus means for interprocessor communications there is provided a fiber optic interconnection system to interconnect the bus means of multiple processor sections to one another, thereby allowing groups of the processor units to be physically spaced from one another. The fiber optic interconnect system includes, for each multiprocessor unit section functions to receive messages communicated on the interprocessor bus of that section for receipt by a destination processor of the other section, format the message for fiber optic transmission, and transmit the message; and circuitry for receiving messages on the fiber optic link, scheduling the message for transmission to the destination processor, and maintaining that scheduling in the face of receipt of another message for the same processor unit. The fiber optic interconnect system includes means for configuring the system to identify which processor units are in which section and, when more than two sections are interconnected by the fiber optic link, provide information as to the shortest route to the destination processor from a section.

The present invention relates to a method for optical fiber transmission which can increase a transmission distance. A first optical fiber having dispersion is first provided. An optical signal is next supplied to the first optical fiber so that the optical signal is compressed on the time axis as propagating in the first optical fiber. In the case that the dispersion is normal dispersion, for example, prechirping is performed so that the optical signal has down-chirp. A compressed optical signal output from the first optical fiber is supplied to an optical device having a saturated gain. According to this method, the transmission distance can be increased by the effective combination of compression of the optical signal and waveform shaping by the optical device.

In one embodiment, a fiber optic link includes a combined optical link for transmitting high optical power and wide bandwidth signal through a single optical fiber. In one embodiment, a means is provided for combining a high power optical signal and a low power data signal with wavelength selective directional couplers so as to inhibit the low power data transmitter and the low power data receiver from being overloaded with too much power. In one implementation, a method of using double clad fiber is provided, which includes transmitting an optical data signal at an optical data wavelength along an inner core, the inner core being single mode at the optical data wavelength and simultaneously transmitting an optical power signal at a optical power wavelength through a cladding, the cladding serving as a multimode core for a power optical link at the optical power wavelength.

An apparatus and system are provided for delivering communication services such as video, data and telephony services to individual residential units.

According to one embodiment, an optical network terminal (ONT) for providing communication services to a single residential unit comprises a passive optical network interface (PI) circuit, a residential service interface (RSI) circuit, and a power unit. The PI circuit receives optical signals from an optical fiber and transmits optical signals onto the optical fiber. The PI circuit is adapted to convert received optical signals containing voice information to electrical voice ATM cells, received optical signals containing data information to electrical data ATM cells, and received optical signals containing video signals to electrical video signals. The PI circuit is also adapted to convert electrical voice ATM cells and electrical data ATM cells to optical signals for transmission over the optical fiber;

The RSI circuit that is adapted to convert the electrical voice ATM cells to a telephony format suitable for use at the residential unit and the electrical data ATM cells to a network format suitable for use at the residential unit. The RSI circuit is also adapted to convert telephony format information received from the residential unit to voice ATM cells and network format information received from the residential unit to data ATM cells.

The power unit provides power for use in the PI circuit and the RSI circuit. The power unit includes an AC/DC converter for converting ac power received from the residential unit to dc power for use in the ONT and backup batteries for providing power when there is an interruption of the ac power.

An optical transport system configured to transmit at least two phase-conjugated optical variants carrying the same modulated symbols, with the phase-conjugated optical variants in being different from one another in one or more of polarization of light, the time of transmission, spatial localization, optical carrier wavelength, and subcarrier frequency during transmission. The two phase-conjugated optical variants can be generated by a single polarization-diversity transmitter to be orthogonally polarized, and propagate through an optical transmission link with the same wavelength and spatial path. The optical variants are detected and processed at the receiver in a manner that enables coherent summation of the corresponding electrical signals prior to constellation de-mapping. The coherent summation tends to cancel out the deleterious effects of nonlinear distortions imparted on the individual phase-conjugated optical variants in an optical fiber transmission link because said nonlinear distortions tend to be opposite to each other.

The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift in the etalon. In one example, the optical components are aligned so that laser wavelength detector receives a portion of the laser beam directly from the laser so that phase characteristics of the laser beam are not affected by an intervening beamsplitter thereby permitting improved wavelength locking. In another embodiment, an etalon chirp filter is provided for reducing or eliminating optical frequency chirp, regardless of the particular ITU channel being used for transmission.

An object of the present invention is to provide a WDM optical transmission system with an excellent transmission characteristic by employing a hybrid transmission line which is formed by combining under optimal conditions an optical fiber having positive wavelength dispersion, and an optical fiber having negative wavelength dispersion. According to the WDM optical transmission system, an optical transmitter station, optical amplifiers, and an optical receiver station are interconnected over an optical fiber transmission line. The optical fiber transmission line has an inter-repeater segment formed with a hybrid transmission line composed of a 1.3 mum zero-dispersion SMF and an RDF, and an inter-repeater segment formed with a DCF for compensating for cumulative wavelength dispersion generated in the hybrid transmission line. As the conditions for setting the hybrid transmission line, a ratio of the length of the RDF to the length of the inter-repeater segment must be 20% or more and 40% or less. Consequently, an influence due to a nonlinear effect or transmission loss in the hybrid transmission line can be minimized to thereby improve a transmission characteristic.

The invention discloses a mixed format signal optical fiber transmission device. The mixed format signal optical fiber transmission device comprises a sending end, a fiber channel and a receiving end, wherein the sending end converts input camera link format video image signals and multi-channel universal serial signals into optical signals, the optical signals are sent to the receiving end through the fiber channel, and the receiving end receives the optical signals and restores the optical signals to original video image signals and multi-channel universal serial data signals. The mixed format signal optical fiber transmission device is suitable for optical fiber transmission of the camera link video image signals and the multi-channel universal serial signals in all configuration modes, the transmission of mixed format signals in a single-fiber channel at different rates can be achieved through multiplexing of a transmission bus, and consumption of extra fiber channels and devices is reduced. According to the mixed format signal optical fiber transmission device, electrical signal conversion processing and transmission control are achieved through a field programmable gate array (FPGA) device, the requirement for actual functions is met, meanwhile, the usage of application-specific integrated circuits is reduced, the advantage of high integration and universalization degrees can be achieved, and supports can be provided for further function extension and performance upgrading.

A wavelength-division-multiplexed light source for transmitting broadband light through a fiber and receiving an optical signal through the fiber is disclosed. The wavelength-division-multiplexed light source includes: a light source for outputting broadband light; and a coupler for outputting the broadband light, which has been input from the light source, to the fiber through cross coupling, and outputting an optical signal, which has been input from the fiber, through bar coupling, based on a predetermined cross coupling ratio, wherein the cross coupling ratio of the coupler is adjusted depending on a power of the optical signal.

A transmitter subsystem generates an optical signal which contains multiple subbands of information. The subbands have different polarizations. For example, in one approach, two or more optical transmitters generate optical signals which have different polarizations. An optical combiner optically combines the optical signals into a composite optical signal for transmission across an optical fiber. In another approach, a single optical transmitter generates an optical signal with multiple subbands. The polarization of the subbands is varied, for example by using a birefringent crystal. In another aspect of the invention, each optical transmitter generates an optical signal containing both a lower optical sideband and an upper optical sideband (i.e., a double sideband optical signal). An optical filter selects the upper optical sideband of one optical signal and the lower optical sideband of another optical signal to produce a composite optical signal.

The invention provides a method for realizing matching between uplink transmission rate and downlink transmission rate of a distributed base station, as well as a building baseband unit (BBU) and a remote radio unit (RRU), and a method for transmitting uplink data by the RRU and a method for receiving uplink data by the BBU. Before being transmitted by the RRU, the uplink IQ data is compressed toreduce the data volume of uplink transmission so as to match the compressed uplink transmission rate and the downlink transmission rate and ensure that optical modules selected by using the transmission rate of uplink fibers as a standard can be suitable for the transmission rate of uplink transmission fibers, thereby reducing the cost of optical modules and simultaneously improving the reliability of hardware circuit design.