Abstract: An optical receiver for receiving an optical differential phase shift keyed signal has an optical component sensitive to the optical phase of the signal, such as an interferometer, a device arranged to generate a control signal by non linear limiting of an output of the optical component, such as an RF amplifier arranged to operate in a region near saturation point, and a phase controller for tuning a phase response of the optical component to the received signal according to the control signal.

Abstract: A passive optical network which employs multiple wavelengths to increase overall system bandwidth, with each wavelength being shared by multiple optical network units (ONUs) according to a time division multiple access (TDMA) protocol. The upstream TDMA traffic therefore includes multiple TDMA data streams at different wavelengths. An optical line terminal (OLT) preferably receives the multiple TDMA data streams and separates them to different detectors before ultimately combining all data into a single data stream using a multiplexer after performing clock and data recovery functions. In this manner, the upstream bandwidth in a passive optical network can be markedly increased without requiring an increase in data transmit speeds, and while using low cost/low speed detectors in the OLT, and low cost/low speed transceivers in the ONUs. System bandwidth can be further improved by using higher cost, higher speed components.

Abstract: An optical network terminator of the present invention includes an optical wavelength division multiplexer for receiving an optical signal and incoherent light. An optical detection unit converts a downstream high speed and low speed optical signals into electrical signals. A laser diode converts an upstream signal into an optical signal. A high speed driving unit is supplied with power from a power supply unit to drive a forward-biased laser diode and establish a data and video channel. A high speed reception unit is supplied with the power to receive a downstream data and video channel. A charging unit outputs charged power at the time of a power failure. A low speed driving unit is supplied with the charged power to reverse-bias the laser diode to establish a voice channel. A low speed reception unit is supplied with the charged power to receive a voice channel.

Abstract: A method for communicating optical traffic in a network comprising a plurality of network nodes includes receiving traffic to be added to the network at a network node. The network is operable to communicate received traffic in an optical signal comprising one or more channels. The method also includes determining a data rate and one or more destination nodes of the received traffic and assigning the received traffic to one or more of the channels of the optical signal based on the determined data rate and the destination nodes. The method further includes configuring one or more of the network nodes to process the traffic contained in the assigned channels based on the data rate and the destination nodes of the optical traffic and communicating the traffic through network in the assigned channels of the optical signal based on the determined data rate and the one or more destination nodes.

Abstract: A method of transmitting an optical communications signal, comprising receiving a first signal, encoding the signal with a differential or duobinary encoding scheme, encoding the signal with an oscillating signal component, and sub-carrier modulating the signal onto a sub-carrier of an optical carrier signal. The invention also relates to corresponding systems and apparatuses.

Abstract: There is provided an optical receiver in which a time gate can be realized with a simple, low-cost configuration, and which has few aspects that require adjustment. The optical receiver of the present invention comprises a decoding circuit in which optical signals which are spread over time in accordance with a coding pattern are inputted and decoded in accordance with a decoding pattern; and a time gate circuit for generating a time gate signal that represents the interval of time in which a significant optical pulse is present in the decoded optical signal, and controlling the passage of the decoded optical signal.

Abstract: A PON and a method of transmitting data employing different upstream and downstream transmission protocols are disclosed. The PON includes: a plurality of ONTs; WDM filters; an OLT receiving and transmitting optical signals to and from the ONTs and a higher network; and an optical coupler. The ONT includes a first switching unit, a level transformer converting two level Ethernet signals into a three level data signals, a first code generator generating a specific CDMA codes that distinguish the ONT from another ONT, and a first multiplier performing a spread spectrum function with the CDMA codes. The OLT includes an optical receiver, a branching filter branching the upstream CDMA signals, a plurality of second code generators generating codes for despread, a plurality of second multipliers multiplying the received signals by the despread codes, and a plurality of data decider extracting data through correlation calculation.

Abstract: An apparatus and method for demultiplexing multiple wavelengths of light. In one embodiment, an optical signal having a plurality of wavelengths is provided to an optical-to-electrical (OE) circuit configured to convert optical signals into electrical signals. The optical signal may include a plurality of wavelengths. The OE circuit converts the optical signal into a first electrical signal. The first electrical signal is received by a demodulating circuit, which also receives a demodulating signal. The demodulating circuit combines both the first electrical signal and the demodulating signal in order to produce a second electrical signal. Both the second electrical signal and the demodulating signal correspond to one of the wavelengths in the optical signal.

Abstract: An optical code division multiple access transmission and reception system is presented. The transmission system comprises an optical comb generator for producing multiple discrete optical signal components comprising a plurality of equally spaced wavelength components. A serial-to-parallel converter is connected with the optical comb generator for receiving receiving the serial signal components and for converting a selected group of the serial signal components into parallel signal components. An optical free-space code mask is connected with the serial-to-parallel converter for receiving the parallel signal components and for selecting two separate groups of optical signal components to generate two subsets of signal components, each for representing an associated binary data value from a data stream. The transmission system may comprise further components to enable transmission via fiber optic cable or into free-space via an antenna.

Abstract: An object of the present invention is to adjust the operating wavelength of a decoder, in order to coordinate the operating characteristics of an encoder and the decoder. To this end, an optical code division multiplex transmission device of the present invention comprises a second SSFBG in the decoder, and has a mechanism to perform adjustment (phase adjustment step) of the fixation portion interval L which is the interval between a first and second fixation portions fixing in place the second SSFBG, such that the extent of the eye opening of optical pulses output from the second SSFBG is maximum. The extent of the eye opening is measured using a correlation waveform monitor, and the measurement data is sent to the wavelength control portion. A signal is sent from the wavelength control portion to the movement control portion to set the fixation portion interval L, based on data relating to the extent of the eye opening sent from the correlation waveform monitor.

Abstract: The present invention is a high-speed and low-cost optical communication network. A preferred embodiment of this optical communication network comprises an accommodation device, optical couplers that are connected to corresponding ports of this accommodation device, and communication terminals that are connected to corresponding optical couplers. Further, data transmitted by the communication terminals to the accommodation device is code-division multiplexed. Because data collision is prevented by means of code division multiplexing, control of the timing with which the communication terminals transmit data is not required. Meanwhile, data transmitted by the accommodation device to the communication terminals is time-division multiplexed because there is no risk of collision.

Abstract: A method for labeling or coding optical conduits is disclosed. The method includes providing an optical conduit, and utilizing reflected light resulting from the transmission of at least one light pulse along the optical conduit to generate a multi-digit code. Still further, the method includes utilizing the multi-digit code to distinguish the optical conduit from other optical conduits. The utilization of Bragg gratings to code or label optical conduits with a unique multi-digit code is also disclosed.

Abstract: Provided is an optical Code Division Multiple Access (CDMA) transmitting apparatus and method for transmitting bipolar data in an optical CDMA system. The optical CDMA transmitting apparatus and method of the present research has a simple structure, including only one optical CDMA encoder and one optical modulator. This technology minimizes multiple access interference by using modified pseudo-noise code in the encoding process, thus improving the optical CDMA transmission performance. The optical CDMA transmitting apparatus includes: an optical CDMA encoding means for encoding lights from the outside into a code or a complement code of the code; and an optical modulation means for transmitting the code or the complement code of the code which is selected in the optical CDMA encoding means based on the polarity (either ‘0’ or ‘1’) of the data inputted from the outside.

Abstract: Methods, apparatus, and systems for an optical communication channel. A data signal is preconditioned prior to transmission over a fiber optic cable to minimize signal distortion and transmitted over a fiber optic cable. Preconditioning may include none, one or more, or all of the following: encoding the data signal using a run length limited code, correlating bits of the data signal, and spreading out the pulses in the time-domain in the data signal. The pulse spreading function can be implemented either in the electrical domain prior to the electrical-to-optical conversion; in the optical domain during and/or after the electrical-to-optical conversion; or a combination of both. During reception, the data signal and clock are recovered. Recovery may include maintaining an amplitude in an electrical signal, filtering the electrical signal, shaping the electrical signal, and removing distortions and intersymbol interference (ISI) from the received electrical signal.

Abstract: A transmitter and transceiver for an optical communication channel may include a data encoder, a partial response (PR) precoder, a pulse filter, and an electrical-to-optical converter to transmit a spread pulse signal over an optical communication channel. The data encoder to encode the transmit data into coded data. The precoder to correlate bits of the coded data together into a precoded signal at the output of the precoder. The pulse filter to spread out the pulses in the precoded signal into a spread-pulse signal at the output of the pulse-shaping filter. The electrical-to-optical converter to convert an electrical spread-pulse signal into light pulses at its optical output. A transceiver may further include an optical-to-electrical converter, an automatic gain controller, a matched filter, a PR finite impulse response equalizing filter, a maximum likelihood sequence estimation detector, and a data decoder in order to decode and recover the data.

Abstract: An optical signal multiplexer/demultiplexer using an orthogonal pseudorandom (PRN) coding scheme for optical mode modulation to produce a plurality of independent optical signals that may be combined into one multiplex signal for transmission over an optical fiber to the receiving end, where the multiplex signal may be demultiplexed by relying on the orthogonal properties of the PRN code to isolate each independent optical signal from the transmitted multiplex signal. In channels subject to mode modulation distortion, one of the signal components may be used as a pilot signal to obtain a correction for channel mode modulation distortion. The PRN optical signal multiplexer/demultiplexer is particularly useful with polarization mode modulation.

Abstract: In 1 to N communication based on code division multiplexing, ranging is performed by following the first to ninth steps. First step: all the optical network units are set to standby status. Second step: first and second optical network units are set to transmission enable status. Third step: the phase shift amount is set for the variable phase shifters of the first and second optical network units. Fourth step: reception of a fixed signal is attempted in the optical line terminal. Fifth step: if the fixed signal is not received, processing returns to the second step, and if received, the phase amount of the variable phase shifter is defined and fixed. In the sixth to ninth steps, an operation the same as the first to fifth steps is performed for the third to N-th optical network units.

Abstract: An optical access network system capable of transmitting and receiving high-speed signals and which allows the number of subscribers to be increased without increasing the number of wavelengths used is provided. An optical line terminal and an optical network unit are joined via an optical fiber transmitting line, a star coupler, and a plurality of branching optical fiber transmitting lines. The optical line terminal and optical network unit are constituted comprising an optical processing section and an electrical processing section. The optical processing section comprises a light-emitting element and a light-receiving element.

Abstract: A method and system for duobinary coding of optical signals, wherein a precoded duobinary signal is supplied to a phase modulator which converts it to a phase-modulated optical signal, an optical filter carries out the function of the coder and converts the phase-modulated signal to an optical duobinary signal, and the duobinary coding results in a reduction in the bandwidth. A wavelength division multiplex system is provided by precoding a number of binary signals and converting them to phase-modulated signals, which are in turn, combined via an optical multiplexer, wherein the multiplex signal formed in this way is supplied to an optical filter which operates simultaneously as a coder for all the signals and produces a group of duobinary signals, and a number of groups of duobinary signals can be interleaved in one another in order to produce a dense wavelength division multiplex signal.

Abstract: A method and system for processing calls in a telecommunications system using fiber extender loops providing a local micro network. Calls originating from subscribers within the local micro network to subscribers that are also provided service within the local micro network are processed and connected by a location base station within the local micro network.

Abstract: A multi-channel direct sequence spread-spectrum communication system with the capability of automatic rate detection consists of a plurality of signal channels and a plurality of data channels. During signaling period, only the signaling channels corresponding to the desired symbol repetition and the data channels corresponding to the highest index among the indexes of all active data channels will be allowed to transmit. During data transmission period, only the active data channels will be allowed to transmit. Receiver will use the information provided in preamble signal and mid-amble signal to obtain the number of symbol repetition, the set of active data channels and etc, and to set up initial synchronization.

Abstract: An optical signal encoder/decoder includes a grating waveguide having an identical number of uniform pitch gratings to the number of code chips of a binary phase optical code, the uniform pitch gratings being formed in a waveguide direction to reflect light of a predetermined wavelength. Here, adjacent gratings corresponding to a position at which the optical code value changes are disposed a spacing apart from each other to give a phase shift of (2m+1)?/2 to the light, and the remaining adjacent gratings are disposed a spacing apart from each other to give a phase shift of n? to the light (m, n: integer).

Abstract: A system for optical communication forms a family of orthogonal optical codes modulated by a data stream. The orthogonal codes are formed by creating a stream of evenly spaced-apart pulses using a pulse spreader circuit and modulating the pulses in amplitude and/or phase to form a family of orthogonal optical code words, each representing a symbol. A spreader calibration circuit is used to ensure accurate timing and modulation. Each code word is further modulated by a predetermined number of data bits. The data modulation scheme splits a code word into H and V components, and further processes the components prior to modulation with data, followed by recombining with a polarization beam combiner. The data-modulated code word is then sent, along with others to receiver. The received signal is detected and demodulated with the help of a symbol synchronization unit which establishes the beginning and end of the code words.

Abstract: A method for communicating information includes modulating a communications signal by orthogonal frequency domain modulation and transmitting the communication signal by a laser and/or light emitting diode carrier signal.

Abstract: Optical communication systems include a central station that encodes data transmitted to multiplexing (mux) stations or user stations. The central station also decodes data received from the mux stations or user stations. Encoding and decoding are performed using codes, such as composite codes, that designate sources and destinations for data. The mux stations, user stations, and the central station have address encoders and decoders that use, for example, fiber Bragg gratings to encode or decode optical signals according to a code such as a composite code derived by combining codes from one or more sets of codes. A passive optical network comprises one or more levels of mux stations that use such address decoders and encoders to receive, decode, and encode data for transmission toward a central station or a user station.

Abstract: A method and apparatus for generating an arbitrary UWB waveform are presented. An optical comb generator generates a serial stream of optical tones and an optical beating tone. A serial-to-parallel converter receives the serial tones and converts them into parallel optical tones. A spatial light modulator receives the parallel optical tones, and independently adjusts at least one of the phase and amplitude of each to generate the components of an arbitrary waveform. Next, each one of a plurality of optical-to-electrical converters receives a parallel optical tone and the selected optical beating tone, which are beat with the optical beating tone, producing electrical notes, representing differences between each parallel optical tones and the optical beating tone. Each antenna element is connected to receive an electrical note and to launch a signal based thereon, such that the launched signals are superimposed to the arbitrary waveform signal.

Abstract: An optical path switching device is provided whereby changeover of optical path can be achieved with higher speed than conventionally. In this optical path switching device, a plurality of despreaders and a plurality of spreaders are connected in a prescribed corresponding relationship, extraction of a desired code path signal from a code division multiplexing signal that is input from an input circuit is performed, by means of despreaders that are capable of code selection and/or setting to OFF, and the extracted code path signal is given a new code by a spreader and output to an output circuit.

Abstract: Communication systems and methods are disclosed that route, detect, and decode encoded optical signals at network nodes based on channel codes assigned to the network nodes. In an example communication system, a network hub includes a channel selector that encodes an optical signal with a channel code assigned to one or more network nodes. The channel selector is configured to encode based on a channel selection signal provided to the channel selector and can include one or more fiber Bragg coders. Code-switched communication systems can include one or more nodes configured in ring, tree, or bus architectures.

Abstract: Apparatus and methods are disclosed for spatially routing an optical pulse (data pulse) of an electromagnetic radiation and containing a specific address temporal profile and possibly additional data. Routing generally involves a unit of active material that is programmed using one or more input beams or pulses of the electromagnetic radiation providing address (i.e., waveform-discriminating) and directional (i.e., pulse routing) information to the active material. During programming, a spatial-spectral grating is created by optical interference on or in the active material of the input pulses encoding the address and directional information pertinent to the data pulse.

Abstract: A system and method for the simultaneous transmission of point-to-point and broadcast signals over an optical network are provided. In accordance with this invention, the user terminals of the system are divided into groups of user terminals, each assigned a different waveband. Each user terminal within one group is assigned a different point-to-point code within its corresponding waveband for encoding and decoding point-to-point signals exchanged with the central office. A signal broadcast code is assigned per groups of users and therefore per wavebands, for all of the users of a same group to use. All signals on all wavebands are transmitted through the network, but each user terminal may only access point-to-point signals addressed to himself and a copy of the broadcast signal.

Abstract: An apparatus and method for spectral dispersion compensation in an optical communication network are disclosed. In one embodiment, the invention comprises an optical medium having a signal distributed over a plurality of wavelengths, a demultiplexer adapted to receive the plurality of wavelengths and divide the plurality of wavelengths into individual wavelengths, and a plurality of dispersion compensation elements each adapted to receive a wavelength. The dispersion compensation elements alter the timing of each wavelength, where the plurality of dispersion compensation elements operates on all wavelengths simultaneously. The invention also comprises a multiplexer adapted to receive each individual wavelength and combine the individual wavelengths onto the optical medium.

Abstract: The encoder/decoder design for spectrum-encoded optical CDMA systems uses waveguide circuits monolithically integrated on one chip to fulfill essential encoding and decoding functions. The integrated device functions as a 1×2 wavelength selective Mach-Zehnder interferometer switch to encode the input broadband light source and to decode the transmitted spectrally encoded signals. The device comprises a frontal 3-dB coupler, a double-ended arrayed-waveguide grating (AWG), and arrays of thermooptic phase shifters and attenuators, together with their symmetric images reflected from the high-reflection coated facet, to realize all required functionality. The thermooptic phase shifters and attenuators are programmable through electronic interface to realize programmable encoding and decoding capabilities. The attenuators are used to equalize the powers and to increase the ON/OFF extinction ratio of all spectral chips.

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 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: A system and method is disclosed for providing multiple classes of communication services on a high-speed, high capacity communication platform over Wave Division Multiplexing (WDM) networks. A predetermined set of light channels of a WDM network is partitioned into one or more sub groups based on their wavelengths, each sub group is assigned for providing exclusively one communication service such as video, audio or data communication services. Each light channel is modulated by a predetermined set of orthogonal codes so that neighboring channel interferences can be minimized. Further, the predetermined set of orthogonal codes can be further divided into an even group and an odd group. These two groups of codes are assigned to two immediate neighboring light channels.

Abstract: A system and method is disclosed for providing high-speed, high capacity data communication over a Wave Division Multiplexing (WDM) network with an efficient re-routing capability. When all light channels between two nodes in the network are loaded with transmission jobs, a transmission traffic congestion is created. In order to avoid or alleviate the congestion, a new alternative route is needed. An alternative route is selected to direct the traffic away from the congested route, and further expand the channel capacity of the alternative route by encoding the light channels in the alternative route with orthogonal codes.

Abstract: An optical network for transmitting optical data signals is proposed, wherein a first network operates with a WDM method, a second network used a CDM method and a third network uses a time-division multiplex method.

Abstract: An optical code division multiple access transmission and reception system is presented. The transmission system comprises an optical comb generator for producing multiple discrete optical signal components comprising a plurality of equally spaced wavelength components. A serial-to-parallel converter is connected with the optical comb generator for receiving receiving the serial signal components and for converting a selected group of the serial signal components into parallel signal components. An optical free-space code mask is connected with the serial-to-parallel converter for receiving the parallel signal components and for selecting two separate groups of optical signal components to generate two subsets of signal components, each for representing an associated binary data value from a data stream. The transmission system may comprise further components to enable transmission via fiber optic cable or into free-space via an antenna.

Abstract: It is an object of the invention to provide an OCDM system which minimizes interferences in the system and maximizes the data throughput in a simple manner. The OCDM system according to the invention is particularly characterized in that the send rate of optical packets to be transmitted in optical channels is different for different optical nodes of the OCDM system. Each node of an OCDM system is allocated one optical channel, for example. Also allocated are the send rates of optical packets to be transmitted in the optical channels, for instance by transmitting an individual frequency to the node.

Abstract: It is an object of the invention to make an optical receiver for an OCDM network addressable both individually and as part of a group of optical receivers. The optical receiver according to the invention is particularly characterized in that it comprises a series combination of two optical filters having different periods. One of the periods serves to receive broadcast signals. By selecting this period at the transmitting end, a group of optical receivers each incorporating a filter with this period can be selected and a data signal can be transmitted to this group simultaneously. The other period serves to control the reception of signals individual to each receiver, with the sum and/or the difference of the two periods being used for receiving the individual signals.

Abstract: A system and method are disclosed for carrying additional information data on multiplexed signals which are modulated on different wavelengths. An information code such as an address or control data for a particular data signal at a selected wavelength is overlaid on the parallel multiplexed signals. The information code may be overlaid by attenuation or changing the amplitude of the different signals. A separate marker channel at a separate wavelength is also multiplexed with the data signals to indicate the presence of an information code. An optical data detector array is used to optically determine the encoded address by comparing the signals with light levels and producing an output when a matching code is detected. The optical data detector array uses a series of detectors each corresponding to the wavelength of light signals carrying the information data.