155 results about "Coarse wavelength division multiplexing" patented technology

An optical fiber ring network includes a plurality of interconnected nodes, each pair of neighboring nodes being interconnected by a pair of optical links. Using coarse wavelength division multiplexing, data is transmitted in both directions over each link, using a first wavelength λ1 to transmit data in a first direction over the link and a second wavelength λ2 to transmit data in a second, opposite direction over the link. The two wavelengths λ1 and λ2 differ by at least 10 nm. Each of the data streams transmitted over the optical link has a bandwidth of at least 2.5 Gbps. Further, each data stream has at least two logical streams embedded therein. A link multiplexer at each node of the network includes one or more link cards for coupling the link multiplexer to client devices, and one or more multiplexer units for coupling the link multiplexer to the optical links. Each link card includes frame buffers capable of storing numerous Fiber Channel frames that are being transmitted to and from the client device(s) coupled to that link card. The link card also includes flow control logic for pre-filling the frame buffers with frames of data before the receiving client devices send flow control messages to request their transmission. The combined effect of the frame buffers and flow control logic is that the full bandwidth of the links can be utilized even when the network nodes are very far apart and the client devices have small input data buffers.

Optical fiber-based distributed communications components and systems employing wavelength division multiplexing (WDM) for enhanced upgradability. The system comprises a plurality of downlink optical transmitters configured to receive downlink electrical radio frequency (RF) signals from a plurality of RF sources and convert the downlink electrical RF signals into downlink optical RF signals. The system also has a wavelength division multiplexer configured to multiplex downlink optical RF signals into a plurality of downlink wavelengths over a common downlink optical fiber connected to a plurality of remote antenna units (RAUs). In this manner, additional downlink optical fibers are not required to support providing additional RAUs in the system. Wavelength-division de-multiplexing can avoid providing additional uplink optical fibers to distribute uplink signals to RAUs added in the system.

The invention discloses a self-correlation optical fiber communication system based on mode division multiplexing. The self-correlation optical fiber communication system based on mode division multiplexing comprises an optical carrier input unit, optical signal modulation units, a wavelength division multiplexing unit, a mode division multiplexing and demultiplexing unit, a wavelength division multiplexing unit and coherent reception units. The mode division multiplexing and reconciliation multiplexing unit comprises a mode multiplexer and mode demultiplexer, and the mode multiplexer and the mode demultiplexer are connected through few-mode optical fibers. The optical carrier input unit is connected with each optical signal modulation unit, the wavelength division multiplexing unit and the mode multiplexer through single-mode optical fibers. The mode multiplexer is connected with the mode demultiplexer through few-mode optical fibers. The mode demultiplexer is connected with the wavelength division multiplexing unit and each coherent reception unit through single-mode optical fibers. The optical carrier input unit is further connected with the wavelength division multiplexing unit. The self-correlation optical fiber communication system based on mode division multiplexing eliminates an expensive narrow line width adjustable local oscillator light source which is arranged at a reception end, enables a laser to be conveniently managed and maintained, is free from using frequency offset estimation in a digital signal processor (DSP) and phase retrieval algorithm, reduces complexity of the DSP and has the advantages of being high in spectrum effectiveness and big in nonlinearity tolerance.

Provided are a wavelength division multiplexing-passive optical network (WDM-PON) in which a reflective semi-conductor optical amplifier (RSOA) is used as each optical transmitter of an optical line termination (OLT) and an optical network unit (ONU) and additional spectrum-sliced light is injected into RSOAs of each of the OLT and the ONU, and a WDM-PON that is combined with time division multiple access (TDMA) technology, by which the number of included ONUs increases and conventional TDMA ONUs can be used.

An embodiment of the invention provides a restructurable ROADM (optical add-drop multiplexer) and WXC (wavelength cross connect), and relatest to the field of communications, the ROADM comprises a line side wavelength switching module, an upper wave module, and a lower wave module; the upper wave module comprises a tunable multiplexer, a first optical switch and a transmitter; the first optical switch is used for connecting the fiber optical wavelength transmitted by the transmitter to the tunable multiplexer; the tunable multiplexer is used for multiplexing the received fiber optical wavelength, generating a WDM optical signal for wavelength division multiplexing, and outputting the WDM optical signal to the line side wavelength switching module; the lower wave module comprises a tunable demultiplexer, a second optical switch and a receiver, the tunable demultiplexer is used for demultiplexing the WDM optical signal from the line side wavelength switching module and outputting the signal through demultiplexing to the second optical switch, and the second optical switch is used for connecting the fiber optical wavelength through demultiplexing to the receiver. The embodiment of the invention reduces cost of ROADM.

A wavelength division multiplexing (WDM) module for transmitting and/or receiving multiple signals simultaneously includes an array of vertical cavity surface emitting lasers (VCSELs) and/or photodetectors, respectively. In the transmitter case, different VCSELs are operated at different wavelengths that change depending on a value of a condition such as temperature and/or one or more other parameters. Multiple VCSELs are assigned to each channel of the WDM. The currently active VCSEL is switched to a different VCSEL assigned to a same channel and preferably having an operating wavelength that is closer to the signal wavelength at the current measured or estimated temperature and/or other parameter value. Multiple photodetectors are assigned to each channel of the WDM, and currently active detector is switched to the second detector within the same channel. A tuning layer and a resonant waveguide grating coupler are preferably integrated into the resonant structure of the VCSEL array and wavelength specific detector array.

Provided is a wavelength division multiplexing (WDM) optical transmission device which is suitable of performing splitting, wavelength multiplexing, switching, and routing on an optical WDM signal in which optical signals having a spectrum close to a rectangle are arranged with a high density, and efficiency of spectral usage is ultimately high in units of wavelengths. A WDM optical transmission device according to the present invention is configured to cause flat portions of adjacent transmission bands on a wavelength spectrum overlap each other.

The invention discloses a hybrid integrated planar waveguide detector chip based on coarse wave decomposing and multiplexing, which comprises an input port region and a detector array region, wherein a waveguide region is arranged between the input port region and the detector array region of the chip; the waveguide region comprises an input waveguide, three Mach-Zehnder interferometers and four output waveguides; the input port region is positioned at the input end of the chip and comprise an input optical fiber arranged in a V-shaped groove, a groove is arranged behind the V-shaped groove and connected with the input waveguide of the waveguide region; and the output waveguides of the waveguide region are connected with the detector array region. According to the invention, a hybrid integrated technology and a plane integration technology are combined, and multi-channel single fiber transmission and miniaturization of a CWDM (Coarse Wavelength Division Multiplexing) demultiplexing device are realized.

The invention discloses a passive optical network system based on Nyquist wavelength division multiplexing and a realization method. The system comprises an OLT (optical line terminal) and N ONUs(optical network unit), wherein the OLT is provided with a multi-carrier generation device and one three-port optical circulator; the multi-carrier generation device generates N paths of optical carriers with an equal frequency interval; N paths of downlink Nyquist wavelength division multiplexing signals are sent to the ONUs via a downlink feed line optical fiber; the three-port optical circulator transmits the N paths of optical carriers to the ONUs via an uplink feed line optical fiber for uplink modulation; and an uplink Nyquist wavelength division multiplexing signal from the ONUs is transmitted to the OLT via the uplink feed line optical fiber. According to the passive optical network system and the realization method., uplink and downlink both adopt the Nyquist wavelength division multiplexing technology, the advantage of WDM-PON (wavelength division multiplexing-passive optical network) is kept, the servable user amount is greatly increased by utilizing the high spectrum efficiency of the WDM-PON, and realization is simple.

The invention relates to a system for realizing network extension and protection functions with wave-division multiplexing annular optical access networks and a method for realizing the network extension and protection functions with the wave-division multiplexing annular optical access networks. The system is characterized in that an OLT (optical link terminal) is connected with M RNs (remote nodes) through an optical fiber to form an annular network, and the remote nodes are connected with ONUs (optical network units) through a distributed optical fiber, wherein the optical link terminal mainly comprises Q=Mq (1+n) optical transmitters, Q receivers, Mq transmitting C wave-band wavelength, Mnq transmitting L wave-band wavelength, Q 1X2 optical switches, three AWGs (arrayed waveguide gratings) of an identical structure and with Q ports, two EDFAs (erbium-doped fiber amplifiers), two optical circulators and a 2X1 coupler; and each remote node on a main ring mainly comprises a 2X2 optical switch, a 1X2 optical switch, two WBs (wavelength blockers), a CWDM (coarse wavelength division multiplexing), four common circulators, a closed circulator, six couplers and an arrayed waveguide grating. A feeder optical fiber is protected by the aid of use of the optical switches at the OLT end and designs of the annular structures and RN structures. By means of effective arrangement of the RN nodes, network scale extension can be realized, typical annular tangent topological structures are realized, network coverage area is greatly widened, and the quantity of users is greatly increased. The system realizes dynamic dispatching of the wavelength by adjusting the wavelength blockers and changing operating ports of the arrayed waveguide gratings, and achieves balance between the cost and the performance.

The invention discloses a single-optical-port wavelength division multiplexing/demultiplexing photoelectric transceiver device. A pin and a glass carrier are respectively arranged above and below a collimating lens of the device. A total reflector plate and a band-pass optical filter array are respectively bonded on the upper surface and the lower surface of the glass carrier. A glass partition is arranged below the glass carrier. An optical circulator is arranged above the glass carrier or on one side surface of the glass partition. A laser transmitting module and a detector receiving module are respectively arranged on the two side surfaces of the glass partition. The single-optical-port wavelength division multiplexing/demultiplexing photoelectric transceiver device has the advantages that since the laser module and the detector module share the same multiplexer/demultiplexer and one public optical port, the input and the output of downlink detector signals and uplink laser signals from the same optical port can be realized, the used device cases and the size of a module can be effectively reduced, the miniaturization and the integration of the device and the module are facilitated and the working wavelength of the device can be applied to the situation of simultaneous working of multi-channel wavelength of CWDM (Coarse Wavelength Division Multiplexing) and LWDM (LAN Wavelength Division Multiplexing).

The invention relates to a passive optical network over wavelength division multiplexing (PON-Over-WDM). The network includes a first WDM coupler, an ONU terminal, a light circulator and a first wavelength converter, wherein the light circulator directs a burst optical signal transmitted by the ONU terminal to the first wavelength converter, and the first wavelength converter is used for performing wavelength conversion of the optical signal and transmitting the wavelength-converted optical signal to the first WDM coupler for coupling after which the optical signal is transmitted through a single optical fiber. The network of the invention is low in cost and flexible in expansion. The network can be accessed by high-capacity ONU equipments or terminal users and is compatible for different equipment suppliers and service providers. The network can be applied to optical communication networks.

In a ring network comprising a plurality of nodes and a 16 channel coarse wavelength-division multiplexing (CWDM) plan, a technique is disclosed for adding and dropping channels that reduces the maximum attenuation loss that any channel encounters—thereby enabling longer rings to be constructed without using optical amplifiers in the ring. The 16 channels are typically distributed between the wavelengths 1310–1610 nm with 20 nm separation between channels. It is obscured that glass fibers have gradually decreasing loss at longer wavelengths in this band. The network includes a hub and several nodes that are interconnected by optical fibers in a ring configuration, where distance from the hub is the minimum value measure in either the clockwise or counterclockwise direction. Channels are assigned to the various nodes based on their wavelength. The channels whose wavelengths are near 1310 nm are assigned to nodes that are progressively closer to the hub.

The invention discloses a PON system with the combination of TDMA and WDM and the LAN function. An OLT is connected with N ONU through an optical coupler; the OLT end includes M transmitter modules Tx with different wavelengths, a receiver module Rx with single wavelength and a CATV RF signal transmitter module Tx; each ONU includes a transmitter module and a receiver module with the function of high speed wavelength switching. The PON system adopts the coarse wavelength division multiplexing technique to realize the multi wavelength downstream data transmission; each wavelength is distributed to a plurality of ONU for sharing through the current TDMA technology so that the system bandwidth is extended; the LAN mode is separated from the PON system by the receiver-transmitter module with the wavelength switching function in the ONU end so that the rapid switching between the PON mode and the LAN mode is realized and the problem of low channel utilization rate found in the traditional access mode is solved.

A technique for processing dense wavelength division multiplexed optical signals in a network node is disclosed. In one embodiment, the technique is realized as an optical power managed network node comprising a dense wavelength division multiplexing device for combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal. The optical power managed network node also comprises a wavelength-selective optical power detector for detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The optical power managed network node further comprises a plurality of attenuators for attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals.

A signal coupler (20) for a passive optical network (PON) system is disclosed. The coupler (20) includes a first port for two-way feeder side communication with a PON terminal (12), a star coupler (29), other ports (23) for two-way distribution side communication with each of plural remote optical network units (ONUs) (30), and a repeater (28) installed on the upstream signal path from the ONUs (30) to the PON terminal (12). Upstream signals from ONUs (30) are received by the repeater (28) without passing through the star coupler (29) by using a coarse wavelength division multiplexer (50) on each distribution fibre and taking out the upstream light before arrival at the star coupler (29) and redirecting it to a receiver array and multiplexer (52). The repeater (28) regenerates each upstream signal and changes its wavelength.

A WDFDM system of a fiber Fabry-Perot sensor includes a broadband light source, a rough WDM device, fibers, a coupler, an index of refraction matching solution, sensors and splitter and a spectrometer, among which, the fiber is an ordinary single-mode one, the sensor is a fiber Fabry-Perot sensor. The rough WDM device is used to divide broadband light into light in multiple channels to realize WDM. The splitter cuts in sensor of different cavity lengths on each channel to realize WDM. Sensor number capable of multiplexing in the WDFDM system is the product of the number of WDM and FDM independently so as to increase the multiplex efficiency greatly and obtain accurate test value.

The invention provides an OFDM (orthogonal frequency division multiplexing)-based downlink data transmission method of a WDM (wavelength division multiplexing)-PON (passive optical network), and a system for implementing the method, wherein the method has longer transmission range and can effectively restrain an FWM (four wave mixing) effect. Each downlink sending module of an optical line terminal performs OFDM modulation on a downlink data stream, and converts generated base band OFDM signals up to an optical domain so as to form downlink optical signals; the downlink optical signals output by the downlink sending module of the optical line terminal have different wavelengths, an optical multiplexer/demultiplexer multiplexes the downlink optical signals output by each downlink sending module into one path of optical signals; and the downlink sending module keeps subcarriers at the central part of an OFDM frequency band vacant while performing the OFDM modulation. The downlink sending module keeps a central frequency band with serious FWM component vacant while performing the OFDM modulation, and the central frequency band is no longer used for carrying valid data, so that the downlink data transmission is less influenced by the FWM effect, and power for generating component of the FWM is greatly reduced.