Abstract: A method and system for self-synchronizing an optical packet network by selecting a seed pulse from among the data pulses within a packet having no synchronization marker, transforming the seed pulse to be optically distinguishable from the remaining data pulses after the packet has been transmitted, and extracting that seed pulse for use in synchronizing the operation of the network. In one embodiment, the process is practiced using a intensity modifier (such as a fast-saturation, slow-recovery amplifier) to modify the seed pulse intensity, and an intensity discriminator (such as an unbalanced NOLM, or a dispersion-shifted fiber and bandpass filter) to extract the differentiated seed pulse.

Abstract: A multiplexing/demultiplexing system has a multiplexor that includes a first plurality of optical switches having a plurality of outputs and a first plurality of optical delay elements coupled to the optical switches. A source of optical light is coupled to the delay elements, and an optical combiner is coupled to the plurality of outputs and a source of framing pulses. A demultiplexor includes a first and second splitter, and a threshold detector coupled to the first splitter. The demultiplexor further includes a second plurality of optical delay elements coupled to the threshold detector, and a second plurality of optical switches coupled to the second splitter and the second plurality of delay elements.

Abstract: A system and method for configuring lightpaths within an optical circuit wherein the source node stores requests for a lightpath between the source node and the destination node. Upon receipt of a token at the source node indicating an available space within a wavelength, the source node selects a request stored within the queue based upon a best fit window protocol. A lightpath is then established between the source node and the destination node responsive to a selected request.

Abstract: The present invention generally provides systems and methods for distribution of radiation among a plurality of optical channels, each of which can include a non-linear optical element. An optical system of the invention can include a source for generating radiation and an optical time-division multiplexer that can deflect, at any given time interval, the radiation into one of a plurality of optical channels.

Abstract: A protocol for an optical network can control the time at which subscriber optical interfaces of an optical network are permitted to transmit data to a transceiver node. The protocol can prevent collisions of upstream transmissions between the subscriber optical interfaces of a particular subscriber group. With the protocol, a transceiver node close to the subscriber can allocate additional or reduced upstream bandwidth based upon the demand of one or more subscribers. That is, a transceiver node close to a subscriber can monitor (or police) and adjust a subscriber's upstream bandwidth on a subscription basis or on an as-needed basis. The protocol can account for aggregates of packets rather than individual packets. By performing calculation on aggregates of packets, the algorithm can execute less frequently which, in turn, permits its implementation in lower performance and lower cost devices, such as software executing in a general purpose microprocessor.

Abstract: A digital switching system comprises: (a) a line card layer containing a plurality of real or virtual line cards; (b) a switch card layer containing a plurality of real or virtual switch cards; and (c) an interface layer interposed between the line card layer and the switch card layer for providing serialization support services so that one or more of the line cards and switch cards can be operatively and conveniently disposed in a first shelf or on a first backplane that is spaced apart from a second shelf or from a second backplane supporting others of the line cards and/or switch cards. Such an arrangement allows for scalable expansion of the switching system in terms of number of lines served and/or transmission rates served. The flexibility of the system is owed in part to payload data being carried within payload-carrying regions of so-called ZCell signals as the payload data moves between the line card layer and the switch fabric layer.

Abstract: This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node.

Abstract: A technique for routing data within an optical network having a plurality of network nodes is disclosed. In one embodiment, the technique is realized by receiving data at a first network node via a first optical signal having a first wavelength. The first wavelength corresponds to a first optical frequency, and the first optical frequency is mapped to a first binary representation. The first binary representation is divided into a first plurality of fields, wherein at least one of the first plurality of fields corresponds to a routing label in a first label stack. A top routing label in the first label stack indicates a second network node. Based at least partially upon the top routing label, the data is transmitted from the first network node to the second network node via a second optical signal having a second wavelength. The first wavelength may be either the same as or different from the second wavelength.

Abstract: A communications signal which carries a purely digital wrapper signal and a method and system for generating it and extracting overhead information therefrom. The wrapper signal can be received by a high-performance format-specific receiver at the end of the network as part of the overall payload, but can also be detected by a low-bandwidth payload-bit-rate-insensitive receiver at an intermediate node. This is achieved by using alternating payload and wrapper segments and providing special digital coding on the wrapper segments. Specifically, each wrapper segment consists of a contiguity of signal level sequences, each of which is a multi-bit symbol that encodes a bit in the overhead bit stream. Each of the symbols is thus a signal level sequence having one of two possible transition patterns, with the appropriate symbol being chosen depending on whether the overhead bit is a logic “zero” or a logic “one”.

Abstract: 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 ?1 to transmit data in a first direction over the link and a second wavelength ?2 to transmit data in a second, opposite direction over the link. The two wavelengths ?1 and ?2 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.

Abstract: An optical time-division multiplexer branches input light into a plurality of optical paths with different optical lengths. At least one path includes a section of optical fiber with an optical length that is adjustable by physical stretching. The input light is separately modulated on each optical path, and the modulated light signals are recombined into a multiplexed output light signal. Adjustment of the optical length of the optical fiber can compensate for changes in input wavelength and adjust the phase of successive pulses in the multiplexed output signal to provide a ?-radian shift that enables long-haul optical transmission.

Abstract: An optical communications apparatus that is superior in terms of the quality of long-distance transmission. The optical communications apparatus has a plurality of time-division multiplexing devices and an optical multiplexer. Each of time-division multiplexing devices generates optical data sequences by subjecting two systems of optical signal sequences to time-division multiplexing. In each optical data sequence, the duty ratio of the optical pulses is 0.5 or greater, and the phase difference between adjacent optical pulses is ? phase. Moreover, the optical multiplexer subjects the optical data sequences input from the plurality of transmitters to wavelength-division multiplexing. Since the duty ratio is set at 0.5 or greater and the phase difference is set at ? phase, the soliton interaction of the optical signal sequences and the interaction between channels can be reduced, so that the reliability of the transmitted data is improved.

Abstract: A method and apparatus for switching data of different protocols through a network are described. In one embodiment, a method includes receiving data from a number of interfaces. Additionally, the method includes switching the data through a first switch fabric upon determining that the data is being processed as packet data. The switching of the data through the first switch fabric includes de-encapsulating a first number of protocol headers from the packet data. The switching of the data through the first switch fabric also includes encapsulating a second number of protocol headers from the packet data. Moreover, the method includes switching the data through a second switch fabric upon determining that the data is being processed as Time Division Multiplexing (TDM) traffic.

Abstract: A fiber optic system for communicating between a central office and a downstream station is described. The central office has a TX unit, an RX unit and a continuous wave (“CW”) laser. Each station has an RX unit and a tunable filter coupling the RX unit to the central office. During downstream transmission, the station's tunable filter is tuned to the central office TX wavelength so that the signal transmitted by the central office will pass through the filter and be received by the station's RX unit. During upstream transmission, the station's tunable filter is selectively tuned to a wavelength different than the CW laser wavelength, allowing selective reflection of light from the CW laser back to the central office. The tunable filter can thus be used to modulate the reflected light to effectively create an upstream transmission from the downstream station to the central office.

Abstract: A network (4) includes optical routers (19), which route information in fibers (10). Each fiber carries a plurality of data channels (16), carrying data in data bursts (28) and a control channel, carrying control information in burst header packets (32). A burst header packet includes routing information for an associated data burst (28) and precedes its associated data burst. Information on the data channels and control channel is organized in synchronized slots. Multiple burst header packets occupy portions of a slot, referred to as micro-slots. When the burst header packets are received, an egress processor (52) schedules the routing of their associated bursts. The egress processor (52) determines a time at which a data burst can be scheduled for passing through an optical matrix (40) to the desired output channel group (the burst can be delayed via fiber delay lines (46) if necessary).

Abstract: An optical digital external modulator having a cascaded arrangement of interferometers is provided. The optical modulator includes an electrode structure for applying an electric field to each interferometer in the cascade and biasing circuitry coupled to the electrode structure for biasing each interferometer at a predetermined bias point. In particular, each predetermined bias point is selected to be above quadrature and for providing improved transmission performance of digital data signals. Preferably, the modulator has a reflective design that helps to increase the modulation bandwidth, lower the drive voltage, and reduce size.

Abstract: A photonic crystal comprising a waveguide made of material. The waveguide has a periodic set of holes. The material proximate to at least one of the holes in the periodic set of holes exhibits an index of refraction that has been modified by the application of laser energy relative to the material proximate to other holes in the periodic set of holes.

Abstract: A first multimode interferometer has a first input port to which an optical signal is applied, a first output port, and a second output port. A first optical waveguide is connected to the first output port of the first multimode interferometer. The first optical waveguide has a refractive index changed in response to a trigger signal externally applied. A second optical waveguide is connected to the second output port. A triggering unit supplies, to the first optical waveguide, the trigger signal for changing the refractive index of the first optical waveguide. An optical switch is provided which can increase the processing speed, can reduce the device size, and is free from dependency on the polarization state of an optical signal.

Abstract: An optical multiplexing apparatus converts input signals from multiple channels to an optical signal including optical pulses multiplexed on the time axis, transmits the optical signal, and controls the average power of the transmitted optical signal so as to maintain constant transmission quality even if the input signal on one or more channels is lost. For example, the average power may be held at a target value that varies according to the combined duty cycle of the multiplexed optical pulses. Alternatively, the average optical power may be held constant and dummy signals may be inserted to replace lost input signals, or to fill idle channels until signal input begins.

Abstract: A synchronization system in accordance with the principles of the invention includes a central synchronizing management unit, at least one synchronization distribution unit, and at least one network element. Each synchronization distribution unit receives synchronization and management information from the central synchronization management unit. This information may be transmitted directly from the central synchronization management unit, or it may be transmitted though another synchronization distribution unit in a group of a daisy-chained synchronization distribution units. The daisy-chained arrangement employs both active and passive optical paths. The central synchronizing management unit may query any synchronization distribution unit within the system to obtain performance statistics.

Abstract: A passive optical network (PON) including an optical line termination (OLT) and a plurality of optical network units (ONUs) which are connected. The optical line termination includes a band setting control section; an upstream control cell receiving section; a use right transmitting section; and a downstream control cell transmitting section. Each of the plurality of optical network units includes a downstream control cell receiving section; a use right acquisition determining section; and an upstream control cell transmitting section.

Abstract: A method and apparatus are provided for transmitting and receiving multiple RF/microwave subcarriers on a single optical wavelength over an optical link. The method includes the steps of modulating a plurality of RF/microwave subcarrier frequencies with a respective communication signal and modulating an optical carrier wave with the plurality of modulated RF/microwave subcarrier frequencies.

Abstract: An optical modulation/multiplexing circuit can fabricate a plurality of nonlinear optical waveguide devices and silica optical waveguides through a small number of processes, and achieve the simplification of the fabrication process and stabilization of the operation by hybrid integration with reduced connection loss. It employs lithium niobate domain inversion optical waveguides as nonlinear optical switches, and implements functions necessary for modulation and multiplexing such as input, splitting, multiplexing and timing adjustment of optical modulation signals and an optical clock signal by connecting glass waveguides to the input and output terminals of the domain inversion optical waveguides. Nonlinear optical media generate a second harmonic light beam of the optical clock signal, and at the same time produces a light beam with a frequency corresponding to the difference frequency of the two high frequency signals, the second harmonic light beam and the signal pulses.

Abstract: An arrangement for controlling multiple telephone lines terminating in a single residence uses a multiplexer within a communications gateway and a plurality of demultiplexers, each demultiplexer coupled to a separate one of telephone lines. The communications gateway functions to convert all received analog telephony signals into a digital format and then multiplexes the digital signals onto a single telephone line connected to the residence. The various telephone lines in the residence are connected in series along the line, using a number of drop-off points. The demultiplexer on each telephone line is configured to recognize the time slots within the multiplexed signal destined for its associated telecommunications device. In a similar fashion, separate time slots are assigned for upstream transmission from each telecommunication device into the HFC network.

Abstract: An optical coding system is provided for a data transmission device with at least one laser transmitter and at least one laser receiver. The laser transmitter has a laser device and a code generator, and the laser receiver a detector device and an evaluation circuit. The detector device is designed for detecting a burst sequence (B1, B2, B3, . . . ), wherein the length d of the pulses of a burst is greater than 400 ns, and the length D of a burst consisting of a number b of pulses is less than 1000 &mgr;s.

Abstract: This invention provides a method and apparatus for spectral power monitoring by use of a polarization diversity scheme. In the present invention, a multi-wavelength optical signal is first decomposed into first and second polarization components, and the second polarization component is subsequently rotated by 90-degrees, prior to impinging onto a diffraction grating that provides a higher diffraction efficiency for the first polarization component. The diffraction grating separates the first and second polarization components by wavelength respectively into first and second sets of optical beams, impinging onto an array of optical power sensors. The inventive optical spectral power monitoring apparatus thus is able to minimize the insertion loss, while providing enhanced spectral resolution.

Abstract: A Mach-Zehnder optical modulator that can attain a higher transmission speed than the driver signal speed but also attains, by setting multi-value amplitudes, an information transmission volume corresponding to an integer multiple of a single driver while allowing the transmission speed to remain as it is, wherein plural optical waveguide branches and plural Mach-Zehnder modulator portions are used, and by utilizing a propagation delay of a modulation signal for driving each of the modulator portions there is attained a transmission speed proportional to the delay time. This leads to a transmission signal having a frequency higher than the cut-off frequency of, for example, an IC or a transmission line substrate having an electrical characteristic of generating and propagating a modulation signal in such a form as an optical MUX (multiplexer).

Abstract: An optical network has an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit via a working optical fiber, (2) a protection OSU of a protection circuit via a protection optical fiber, and (3) one or more optical network terminals (ONTs), where the protection OSU has a protection burst mode receiver (BMR) configured to receive an upstream optical signal from the optical splitter. The algorithm determines whether the protection OSU is functioning improperly. A reset pulse is applied at the protection BMR at a particular timing position and an attempt is made to interpret the current upstream cell received at the protection BMR. This process is repeated using different timing positions for the BMR reset pulse until the current upstream cell is correctly interpreted, e.g., based on the correct identification of an ATM header error correction (HEC) byte in the upstream cell.

Abstract: An optical TDM multiplexing apparatus to multiplex a plurality of input signals in the optical stage in the time domain according to the invention comprise a plurality of signal light sources to generate optical signals each having a wavelength different from the others to carry each of the plurality of the input signals, a timing adjuster to adjust timings between the respective optical signals so that each optical signal output from the plurality of the signal light sources is disposed on a time slot different from the others in the time domain, an optical multiplexer to multiplex each optical signal output from the timing adjuster in the wavelength domain and a wavelength converter to convert each wavelength of the output light from the optical multiplexer into a predetermined wavelength.

Abstract: An optical network has an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit, (2) a protection OSU of a protection circuit, and (3) one or more optical network terminals (ONTs), where an ONT has (i) a working line termination (LT) unit of the working circuit and connected to the optical splitter via a working optical fiber and (ii) a protection LT unit of the protection circuit and connected to the optical splitter via a protection optical fiber. The present invention enables fast protection switching from the working circuit to the protection circuit. The arrival times of corresponding downstream cells are measured at both the working and protection LT units of the ONT, and information related to the arrival times is transmitted from the ONT to the protection OSU.

Abstract: The capacity of an optical transmission system can in principle be increased by interleaving two bits streams with orthogonal polarisation states. This requires, in the interleaved bit stream, the bits of one component bit stream to be timed to occur close to midway between the bits of the other component bit stream. Achieving this by adjustment of relative optical path lengths upstream of the interleaver requires control of those lengths to ±200 microns for ±1 ps bit interleaving accuracy. Such precision is awkward to achieve using fusion splicing. Instead, the necessary precision of interleaving accuracy is achieved by trimming a length of birefringent fiber inserted downstream of the interleaving, this fiber oriented to have its principal polarisation planes (principal axes) aligned with the polarisation states of the two bit streams. Employing birefringent fiber with a beat length of 2.

Abstract: An optical-path-superposing-and-separating unit superposes optical paths of two inputted signal lights with each other, and then separate them. A non-linear waveguide is arranged in an area where the optical paths are superposed with each other. First and second optical waveguide are connected to the optical path superposing-and-separating unit. The second optical waveguide has a longer optical path than the first optical waveguide. A control light is introduced to the non-linear waveguide. An interference separator distributes the inputted two signal lights depending on a phase difference therebetween. Third and fourth optical waveguides connect the optical-path-superposing-and-separating unit to the interference separator.

Abstract: An multiplex transmission apparatus that realizes a receiving system using a phased array antenna with high efficiency and low cost is provided. A delay controller 102 gives a time delay to a local oscillation signal outputted from a signal source 101. First and second optical transmitters 1031 and 1032 each converts the local oscillation signal and the delayed local oscillation signal into optical signals. A first optical multiplexer 104 multiplexes the optical signals for transmission. An optical separator 106 separates the multiplexed optical signal. A first multiplexer 1071 multiplexes first and second main element signals, while a second multiplexer 1072 multiplexes first and second sub-element signals. First and second optical modulators 1081 and 1082 each modulates the optical signal with multiplexed electrical signal group. A second optical multiplexer 109 multiplexes the modulated optical signals for transmission.

Abstract: It is an object of the present invention to perform optical pulse separation that employs a clock recovery method that does not necessitate a complex constitution and by means of which operation is stable even during high-speed operation in excess of 160 Gbit/s. Hence, the clock signal required in the optical pulse separation is extracted by means of a clock recovery stage. The clock recovery stage is constituted by an O/E converter that has a reception bandwidth enabling a clock frequency signal to be received, a phase-locked loop for obtaining a recovered clock signal in which the jitter of the time division multiplexed optical signal is faithfully reproduced, an electrical phase delay circuit, and a high Q value bandpass filter, and the like. The time division multiplexed optical signal is received by the O/E converter and O/E converted thereby. The O/E converted electrical signal is supplied to the phase-locked loop.

Abstract: An optical superposition network that utilizes a time division multiplexing (TDM) protocol includes a first optical transmitter, a second optical transmitter and a receiver. The first optical transmitter transmits information in a tertiary mode during a time slot. The second optical transmitter transmits information in a tertiary mode during a different time slot. The information transmitted across the optical superposition network has an approximately constant average intensity such that the receiver can utilize a single decision threshold for the information received from the first and second optical transmitters.

Abstract: In a signal demultiplexing device formed by a probe light source, a wavelength converter, and a wavelength demultiplexer, the probe light source is formed by a plurality of sub-probe light sources configured to respectively generate the sub-probe lights with the prescribed different wavelengths for respective time-slots, a multiplexer configured to multiplex the sub-probe lights generated by the plurality of sub-probe light sources, and a phase different giving unit configured to give phase differences corresponding to time-slot positions to the sub-probe lights multiplexed by the multiplexer, and to sequentially output the sub-probe lights with the phase differences in correspondence to respective time-slots.

Abstract: A method for communicating data over a network having a plurality of nodes thereupon is discussed. A time slot clock signal is transmitted from one node of the plurality of nodes to other nodes of the plurality of nodes. After each of the other nodes of the plurality of nodes receives the time slot clock signal, the time slot clock signal is recalculated to achieve an integer number of slots on the network. The recalculated time slot clock signal is transmitted from the one node of the plurality of nodes to the other nodes of the plurality of nodes.

Abstract: The present invention discloses a packet transmission device and a packet transmission system which can realize high-capacity communication. The transmission device transmits packets over a wavelength division multiplexing (WDM) link by mapping the packets into an optical path signal directly without any other medium such as an SDH path. The present invention also discloses a packet transmission device and a packet transmission system which can realize high-capacity communication over an SDH transmission link by mapping the packets directly into an SDH section payload without adding any VC path overhead in order to use the entire SDH section payload area.

Abstract: Splitting circuitry receives external telecommunications lines and splits them into corresponding primary and secondary lines for implementing an N:l sparing arrangement in an associated telecommunications system. Sparing circuitry receives the secondary lines and includes selection circuitry and a sparing bus, where the selection circuitry selectively connects a desired group of secondary lines to the sparing bus in response to a selection control signal. Preferably, the telecommunications system routes communications traffic between subscriber equipment connected via the external telecommunications lines and a larger communications network using N primary line interfaces coupled with the primary lines. When desired, the telecommunications system controls the sparing circuitry such that secondary lines corresponding to a group of primary lines associated with a given primary line interface connect to the spare line interface.

Abstract: A so-called digital “wrapper” is employed in conjunction with an optical channel client signal payload envelope to carry optical channel associated optical channel overhead. That is, the digital wrapper transports optical channel associated optical channel overhead and other monitoring information. This is realized by adding additional capacity, i.e., bandwidth, to the client signal payload envelope. The additional capacity is added “around” the payload envelope and the client signal floats in the payload envelope. This is effected in such a manner that the digital wrapper is independent of the type of client signal that is being transported on the optical channel. Indeed, as such the optical payload envelope is essentially a client optical signal independent, constant bit-rate channel. Moreover, in addition to the digital wrapper providing capacity for the optical channel overhead, it can also be employed to provide a forward error correction capability.

Abstract: A method and system deliver multiple-band broadcast services in a network such as a wavelength division multiplexed passive optical network. In the transmitter and/or receiver of such a system, filters are cascaded to stack data corresponding to different services within different free spectral frequency ranges of an optical transmission signal. Each filter is used to select a portion of a free spectral frequency range to be delivered to a user node. Each transmitter filter confines the output from spontaneous emission sources to a desired spectral region. The cascaded filters can also combine multiple spectra and/or separate combined broadcast spectrum. The method can also be used to partition the output from a broadband spectral source into different portions in the spectral domain.

Abstract: A method for requesting a grant for Medium Access Control (MAC) being applied to a Passive Optical Network (PON) system. The method includes the steps of: a) deciding a period of a mini slot (Tms), which is necessary for a plurality of Optical Network Units (ONU) to transmit upstream cells to an Optical Line Termination (OLT); b) deciding a period of a divided slot (Tds) and a link overhead (Co) based on the period of the mini slot (Tms); c) calculating a length of the mini slot based on information to be transmitted to the OLT and a protocol being used; and d) requesting a grant for a MAC protocol between the plurality of the ONUs by calculating and allocating optimal parameters based on the length of the mini slot.

Abstract: A communications network includes optical network terminations (ONTs) and an optical line termination (OLT) connected to a passive optical network (PON). The OLT measures round trip transmission delay expressed in time slot duration for each of the ONTs, and orders the ONTs in ascending order of respective delay modulo time slot duration. A desired reception time at the OLT is scheduled for each of the OLTs according to the ascending order and each ONT is commanded to transmit at a command time that leads the respective desired reception time by a respective delay integral time slot duration. The scheduling includes leaving a reception interval spare after the last ONT in ascending order. The ascending delay modulo slot protocol becomes more efficient as the number of time slots per frame increases. If the number of time slots per frame is N, then the efficiency of the protocol is (N−1)/N. Unassigned time required per transmission frame is thereby reduced.

Abstract: A lightwave network data communications system having such an architecture that routing operation within a lightwave network is simplified, and a high-speed transfer process is attained in a large-scale basic network utilizing a wavelength division multiplexing (WDM) technology which accommodates internet traffics from a plurality of subscriber networks.

Abstract: A course wavelength division multiplexed optical network for transmitting time division multiplexed optical signals is disclosed. For downstream transmission, an optical line terminal generates a plurality of single wavelength optical signals having embedded time division multiplexed data streams. The single wavelength optical signals have channel spacing of at least approximately 20 nm. The single wavelength optical signals are multiplexed onto a multi-wavelength optical signal for transmission via an optical fiber. The multi-wavelength optical signal is demultiplexed into its component single wavelength signals using a course wavelength division demultiplexer. Each of the single wavelength signals is then split into multiple identical single wavelength signals for transmission to end users. Each of the users extracts its associated data stream from its assigned time slot.

Abstract: In an optical multiplexing communication system, a frequency conversion of the optical multiplexed signals having different amplitudes for different communication channels into a plurality of optical pulse sequences having different carrier frequencies for different communication channels is carried out, and the plurality of optical pulse sequences obtained by the frequency conversion are demultiplexed into optical pulse sequences for different communication channels.

Abstract: Methods and apparatus for implementing synchronous Optical Time Division Multiplexing are presented. Namely, a method of upconverting and combining N input NRZ optical data signals, each having an approximately equal pulse width and period, into one time-division multiplexed output signal, as well as a method for the inverse, i.e., down converting the N demultiplexed component signals are presented. Apparatus to implement these functionalities is also presented.

Abstract: An optical time multiplexer for generating an N Gbits/s output signal (36) from n data modulated input pulse streams (21, 22) with a pulse frequency of N/n GHz, where n∈IN and n≧2, with a combiner device for passively interleaving the n input pulse streams (21, 22) is characterized by at least n−1 first phase shifting elements (25) tuning the optical phases of at least n−1 input pulse streams (22) and being connected to a controller device (32), which derives at least n−1 control signals from a comparison of the optical phases of the n input pulse streams (21, 22) and controls the at least n−1 first phase shifting elements (25) such that the optical phases of all n input pulse streams (21, 22) are locked with respect to each other.

Abstract: A communication system between head-ends and end-users is provided which expands bandwidth and reliability. A concentrator receives communication signals from a head-end and forwards the received communication signals to one or more fiber nodes and/or one or more mini-fiber nodes. The concentrator demultiplexes/splits received signals for the mini-fiber nodes and the fiber nodes and forwards demultiplexed/split signals respectively. The mini-fiber nodes may combine signals received from the head-end with loop-back signals used for local medium access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and/or fiber node and transmitted to the concentrator. The concentrator multiplexes/couples the mini-fiber node and the fiber node upstream signals and forwards multiplexed/coupled signals to the head-end.

Abstract: A fully “time tunable” all-optical demultiplexer selects which digital bits or groups of bits in an all-optical data packet or all-optical data burst are to be read/demultiplexed. The all-optical demultiplexer is implemented in either a semiconductor hybrid or in a completely monolithic form. The all-optical demultiplexer is formatted in either a “normally on” or “normally off” configuration. Variable time delay elements adjust the time delay of a clocking signal input and a data packet input. The clocking signal determines the state of two nonlinear optical elements, such as semiconductor optical amplifiers, incorporated in the upper and lower arms of a Mach-Zehnder configuration. Only desirable digital bits or groups of bits are outputted from the demultiplexer. All other undesirable bits are suppressed.