Abstract: An energy efficient OFDM transceiver includes a transmitter using a decision processor to control first internal elements that can be operated in parallel and can be selectively powered off or hibernated, and a receiver using a processing decision element to control second internal elements that can be operated in parallel and can be selectively powered off or hibernated, wherein control of the first and second internal elements enables tracking status of network traffic, adjustment of OFDM bandwidth based on a traffic decision and selectively powering off or hibernating parallel ones of the first and second internal elements.

Abstract: Systems and methods are disclosed to provide optical communication by using subcarriers as individual bases functions, obtaining signal constellation points of an N-dimensional pulse amplitude modulation (ND-PAM) constellation diagram as an N-dimensional Cartesian product of a one-dimensional PAM; and transmitting the N-dimensional signal constellation point over all N orthogonal subcarriers serving as individual bases functions.

Abstract: The present invention is directed towards a frequency modulated (FM) burst mode optical system that allows optical signals having a common wavelength provided by a plurality of FM burst mode optical transmitters to be passively combined onto a single optical fiber. A single FM optical receiver receives the combined signals and processes them accordingly. Each FM burst mode optical transmitter includes an FM modulator, a carrier detect circuit and a laser. The FM modulator modulates a carrier signal, such as a 1.21 GHz signal, with received reverse electrical signals. When a subcarrier signal is detected by the carrier detect circuit, the laser is turned and the frequency modulated carrier signal is used to intensity modulate a laser to provide an optical signal. Due to the burst-mode transmission of optical signals, the optical signals can be passively combined and transmitted to a single optical receiver.

Abstract: A method and apparatus for receiving digital information transmitted via an optical signal over an optical channel wherein the optical signal includes an optical carrier (402) and at least one information-bearing optical sideband (404) in the optical frequency domain. The transmitted optical power is distributed between the optical carrier (402) and the optical side band (404). The received optical signal is processed in order to increase the received power in the optical carrier (402) relative to the power in the optical side-band (404). The processed optical signal is detected in order to produce a corresponding electrical signal. The electrical signal is then processed in order to recover the digital information.

Abstract: OFDM (Orthogonal Frequency Division Multiplexing) has been proposed for processing signals over WDM channels in an optical network. The number of OFDM sub-carrier channels utilized in transmitting optical signals from a transmitting node to a remote is adapted to the quality of transmission in a WDM channel. Responsive to control signals from the remote node, the number of used sub-carrier channels is set to optimize optical performance of the WDM channel.

Abstract: The present disclosure provides a transmission system, apparatus and method to provide for variable channel spacing in multiplexed or combined optical signals for transmission over a network infrastructure. The channel spacing may be monitored and maintained at desired values in order to maximize the channel density under various conditions related to the network infrastructure. The individual carrier frequencies associated with each signal channel of the transmission system may be individually controlled to define the desired channel. The channel spacing may be altered to provide for higher channel densities increasing system capacity, or to provide for lower channel densities improving the overall reach of the transmission system. The channel spacing may be continuously monitored and maintained at desired values allowing for rapid and automated reconfiguration of the transmission system, which may result in maximized capacity and reduced costs.

Abstract: A programmable optical network architecture and associated components employing a two-level orthogonal frequency division multiplexing (OFDM)/wavelength division multiplexed (WDM) mechanisms for bandwith virtualization.

Abstract: A broadband receiving apparatus includes an antenna to receive a radio signal having a plurality of modulation frequencies. An amplifier drives a laser source from the broadband radio signal to produce an optical signal having a plurality of spectral components. A diffraction grating transforms the optical signal into its spectral components. An array of photo-detectors converts the spectral components into electronic signals corresponding to the plurality of modulation frequencies. A transmitting apparatus includes an array of coherent laser emitters driven by electronic signals corresponding to a plurality of modulation frequencies to produce optical signals corresponding to a plurality of spectral components. A diffraction grating inverse transforms the spectral components into a composite optical signal. A photo-detector converts the composite optical signal into a composite electronic signal including the plurality of modulation frequencies.

Abstract: A storage area network extension, network and method include a storage terminal coupled to a remote node. The remote node is connected to a passive optical network (PON) for transferring data signals in the PON and storage signals to/from the storage terminal by employing subcarrier channels in the PON to enable concurrent bidirectional transfer of the data and the storage signals. A storage area network is coupled to the storage terminal and configured to store and retrieve the storage signals for transfer over the PON.

Abstract: A receiver receiving a phase-modulated optical frequency division multiplexed signal is provided. The receiver includes a light spectrum shaper configured to extract a carrier wave and a modulated light component contained in either one of a short-wavelength-side waveband or a long-wavelength-side waveband with respect to the carrier wave, to output a spectrum-shaped light signal; and an optical-to-electric converter configured to convert the spectrum-shaped light signal into an electric signal.

Abstract: A radio-over-fiber (RoF) hybrid wired/wireless transponder is disclosed that is configured to provide both wireless and wired communication between a hybrid head-end and one or more client devices. The hybrid transponder includes optical-to-electrical (O/E) and electrical-to-optical (E/O) conversion capability and is configured to frequency multiplex/demultiplex electrical “wired” signals and electrical “wireless” signals. The electrical wireless signals are wirelessly communicated to the client device(s) via a multiple-input/multiple-output (MIMO) antenna system within a cellular coverage area. The electrical wired signals are communicated to the client device(s) via a wireline cable that plugs into a wireline cable port on the transponder. The hybrid RoF system includes a hybrid head-end capable of transmitting and receiving wired and wireless optical signals, and an optical fiber cable that is optically coupled to the hybrid head-end and to at least one hybrid transponder.

Abstract: A receiver for demodulating optical OFDM signals may detect an optical OFDM signal that includes a carrier and data subcarriers by optically splitting the carrier from the subcarriers using a frequency selective filter and then recombining the carrier and the subcarriers using an optical coupler and balanced detector.

Abstract: A wireless transmit/receive unit (WTRU) that may receive an asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) signal is disclosed. The ACO-OFDM signal may include an ACO-OFDM symbol and the ACO-OFDM signal may be generated with or without a pilot or training data. Where the ACO-OFDM signal may not include a pilot or training data, the WTRU may determine a correlation minimum between a first part of N samples of the ACO-OFDM symbol and a second part of N samples of the ACO-OFDM symbol. The correlation minimum may indicate an estimated boundary of the ACO-OFDM symbol which may provide the WTRU with timing synchronization information. Where the ACO-OFDM signal may include one or more ACO-OFDM pilot symbols on one or more pilot subcarriers, the WTRU may interpret an amount of training data included in the one or more ACO-OFDM pilot symbols that may provide information for channel estimation.

Abstract: A system (100) for transmitting digital information includes a transmitting apparatus (102) for generating an optical signal bearing digital information, a dispersive optical channel (104), and a receiving apparatus (110) for receiving the optical signal. The dispersive optical channel (104) is disposed to convey the optical signal from the transmitting apparatus (102) to the receiving apparatus (110). The transmitting apparatus includes an encoder (114) for encoding digital information into a series of blocks, each including a plurality of data symbols corresponding with one or more bits of digital information. A signal generator (118) generates a time-varying signal corresponding with each of said blocks.

Abstract: An apparatus and method are provided for receiving an optical signal having an optical carrier component and at least one information-bearing optical sideband. In general, an optical filter arrangement (110) is used to separate the optical carrier component from the information-bearing optical sideband. First and second optical splitters (126, 128) divide the optical power in the optical carrier and the optical sideband, respectively, into corresponding sub-components. The sub-components of the optical carrier have substantially orthogonal polarisation states, which is an optional characteristic of the sideband sub-components. First and second optical coupling devices (142, 144) respectively each combine one of the optical carrier sub-components with a corresponding one of the optical sideband sub-components. Optical detectors (158, 160) detect the outputs of the combiners (142, 144).

Abstract: A network system and method include a wireless base station integrated at a central office of a service provider. The wireless base station is configured to provide portable and fixed services to customers. A passive optical network is coupled to the wireless base station at the central office to provide a link to extend an antenna for wireless operations of the wireless base station to a remote site such that a wireless signal from the wireless base station is transmitted in parallel with a passive fiber network signal through the link.

Abstract: The present invention provides a system and method of optical communications that utilize coherent detection technique and optical orthogonal frequency division multiplexing for phase encoded data transmission. In particular the invention addresses a device and method for digital polarization compensation of optical signals with up to 100 Gb/s transmission rate received via an optical link. The polarization compensation operates in two modes: acquisition mode and tracking mode. The polarization recovery is performed at the receiver side using the received digital signal conversion into frequency domain and separate reconstruction of the polarization state in each spectral component.

Abstract: A method for data processing in an optical network includes providing at least one main wavelength and processing a subcarrier modulation for the at least one main wavelength, wherein a portion of the subcarrier modulated signal is suppressed. An optical network component and a communication system having such an optical network component are also provided.

Abstract: The invention provides a system and method for secure communication that involve encoding and transmitting an optical orthogonal frequency division multiplexed (OFDM) signal. Each subcarrier of an optical carrier in OFDM transmission is modulated with data individually, and a variety of data format are used, such as QPSK, OOK, QAM, etc. The data format of each subcarrier may change in time according to a predetermined pattern. An optical receiver uncovers the data transmitted via an optical link. It is based on a coherent optical receiver and a digital signal processing (DSP) unit. A key to the data mapping and change is transmitted via the same optical link or by a separate channel. In one embodiment, the key is transmitted using quantum encryption technique. Besides subcarrier modulation encoding, the system may provide additional layers of security: optical carrier frequency hopping and polarization scrambling.

Abstract: The present invention is directed towards monitoring and adjusting a power level of reverse subcarrier signals at an input of an optical node as opposed to at an input of a CMTS blade. Advantageously, reverse subcarrier signals are digitally transmitted throughout the optical link thereby avoiding the use of attenuators in the optical link. Therefore, any attenuation of the power level of the reverse subcarrier signals is caused by an RF feeder portion of the communications system. The CMTS blade then detects the power level of the reverse subcarrier signal that is equivalent to the power level at the input of an optical node and sends a control signal to CPE adjusting the transmitter power level without affecting the optical node dynamic range.

Abstract: Wired/wireless optical signal modulation and demodulation apparatuses and methods using an intensity modulation/direct detection method and an orthogonal frequency division multiplexing (OFDM) method are provided. A unipolar OFDM symbol frame is generated by determining the polarity of each of a plurality of sub-frames of a bipolar OFDM symbol frame which comprises both a plurality of positive pulses and a plurality of negative pulses, inverting the polarity of the sub-frames which are determined to be negative, delaying one of the positive sub-frame and a positive sub-frame obtained through the inversion by the duration of the sub-frames, and multiplexing the result of the delaying and whichever of the positive sub-frame and the positive sub-frame obtained through the inversion is not the result of the delaying. The unipolar OFDM symbol frame can guarantee high power amplification efficiency and high transmission power efficiency, and is robust against a multi-path channel environment.

Abstract: The invention relates to a method of operating a passive optical network. The passive optical network comprises an optical line termination being connected via optical fibers to a number of network terminations. The method comprises the step of generating an optical signal to be transmitted on one of the optical fibers comprising a number of signal states. The method is characterized in that the number of signal states is changed.

Abstract: Systems and methods are presented herein to achieve data privacy in the optical realm such that electronic encryption bottlenecks are removed, potentially increasing data transmission speeds to the limit of fiber optic media. In this regard, privatizing an optical data transmission may include dynamically altering a temporal length of data bits in an optical data transmission or dynamically altering a temporal length of data frames in an optical data transmission. For example, in a two-dimensional OCDMA signal, the temporal length of data bits may be altered by changing the number of time chips on a per bit basis (e.g., using OCDMA signatures having different temporal lengths). In an optical data bit scrambling signal, the temporal length of data frames may be altered by changing the number of time slices on a per data frame basis.

Abstract: A wavelength division multiplexing passive optical network system is provided. A central office generates a multi-mode light having a mode interval equal to a period interval of a multiplexing filter of the remote node and the multi-mode light is used to control a wavelength of an uplink transmission optical signal of the optical network unit. A remote node multiplexes the multi-mode light with the multiplexing filter to transmit the multiplexed multi-mode light to the optical network unit and demultiplexes the uplink transmission optical signal to transmit the demultiplexed uplink transmission optical signal to the central office. An the optical network unit generates the uplink transmission optical signal by modulating a data signal with a Fabry-Perot laser which uses the multiplexed multi-mode light as an injection optical source. Accordingly, it is possible to control a wavelength of a transmitter of the optical network unit by using the injection optical source generated by the central office.

Abstract: A method and apparatus is provided for reducing clipping arising in an optical transmitter. The method begins by generating a frequency multiplexed sub-carrier signal onto which information is modulated at a plurality of different sub-carrier frequencies. The method continues by decorrelating in phase at least some pulses that are formed when two or more of the different sub-carrier frequencies are in phase with one another. An optical output produced by a laser is modulated in accordance with the frequency multiplexed sub-carrier signal after at least some of the pulses have been decorrelated in phase.

Abstract: The present invention provides a WDM optical system that includes a tunable filter for selecting one or more optical channels from a WDM optical signal. A portion of a WDM signal enters a first optical filter stage that exhibits a periodic transmission spectrum and possesses individually tunable filter elements. A second optical filter stage receives throughput from the first filter stage and has a periodic transmission spectrum and individually tunable filter elements. A controller electrically communicates with the optical filter to select individual optical channels from the portion of the wavelength division multiplexed optical signal received through the filter input port; each selected optical channel is output via a filter throughput port. In an exemplary embodiment, each tunable filter element is a micro-ring resonator and the micro-ring resonators in the first filter stage have a different free spectral range (FSR) than the micro-ring resonators of the second filter stage.

Abstract: A passive optical network includes: a central office for generating multiplexed downstream optical signals and receiving an upstream optical signal; a plurality of optical network units for receiving a corresponding downstream optical signal and generating subcarrier channels carrying electrical data of an assigned frequency; and a remote node for photoelectrically converting the channels into electrical data, electro-optically converting the electrical data into at least one upstream optical signal.

Abstract: Multi-carrier modulation fiber optic systems constructed using a series of electrical carriers, modulating the data on the electrical carriers and combining the carriers to form a wideband signal. The wideband signal can then be intensity modulated on a laser and coupled to a fiber optic channel. A receiver may then receive the laser signal from the fiber optic channel and convert it into an electrical signal. Multi-carrier modulation may be applied to existing fiber channels, which may be of lower quality. Existing fiber channels may have characteristics which prevent or restrict the transmission of data using intensity modulation at certain frequencies. An adaptive multi-carrier modulation transmitter may characterize an existing fiber optic channel and ascertain the overall characteristics of the channel. The transmitter and receiver can then be configured to use various bandwidths and various modulations in order to match the transfer characteristic of the fiber channel.

Abstract: An optical interface method includes producing a digital wrapper signal by synchronizing a client signal that is inputted via an optical transmission channel with an oscillating frequency of a fixed oscillator; returning the digital wrapper signal back into the client signal; and outputting the client signal obtained from the digital wrapper signal by the returning onto the optical transmission channel. The oscillating frequency of the fixed oscillator is set higher than a frequency of the client signal in the optical transmission channel.

Abstract: The present invention is an optical multiplex communication system in which an optical wavelength division channel and an optical code division channel can coexist, wherein a WDM channel section 86 has a wavelength demultiplexer 36 and WDM channels W1 to W4. An optical pulse string 83-3 is demultiplexed by the wavelength demultiplexer 36, and for channel W1, an optical pulse 37 with wavelength ?1 is input to an intensity modulator 114 and converted into an optical pulse signal of channel W1, and is output as a wavelength division optical pulse signal 115, where transmission information of channel W1 is reflected.

Abstract: A modulated optical system with cross-modulation compensation reduces or corrects cross-modulation that might occur in a multichannel RF signal modulating a laser. The system detects the cross-modulation, for example, by detecting an envelope of the RF signal or by detecting RF power fluctuations, generates a cross-modulation detection signal, and imparts a compensating cross-modulation by adjusting a bias current of the laser in response to the cross-modulation detection signal.

Abstract: A receiver for demodulating optical OFDM signals may detect an optical OFDM signal that includes a carrier and data subcarriers by optically splitting the carrier from the subcarriers using a frequency selective filter and then recombining the carrier and the subcarriers using an optical coupler and balanced detector.

Abstract: An optical receiver circuit is provided which is able to receive optical signals having a variable transmission rate, without loss of data. The optical receiver circuit according to the present invention has a light-receiving section for converting an optical signal with a variable transmission rate into an electric signal. A recovery section recovers a plurality of different clock signals and data corresponding to possible transmission rates. These data are stored into a plurality of memories and at the same time a decision section decides the transmission rate. A switch section reads data from one of the memories selected according to the result of the decision.

Abstract: System, apparatus and method of optical communication are provided for performing efficient channel estimation for a CO-OFDM link utilizing an intra-symbol frequency-domain averaging (ISFA) to compensate for transmission impairments. An exemplary method includes receiving a pair of training symbols in an optical orthogonal frequency-division multiplexed (OFDM) signal, performing channel estimation to obtain a first estimated channel matrix for each of a plurality of subcarriers of the OFDM signal; and averaging the first estimated channel matrix of a first subcarrier with the first estimated channel matrix of others of the subcarriers to obtain a second estimated channel matrix for the first subcarrier. The second estimated channel matrix may be an average or weighted average. Prior to the averaging, compensation of chromatic dispersion may be performed. Channel compensation is performed based on the second estimated channel matrix for the first subcarrier of the OFDM signal and symbols then decoded.

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: A transmission apparatus for use in fixed bandwidth communications and variable bandwidth communications. The transmission apparatus has a memory unit, which stores information contained in a frame and indicating the amount of data to be transmitted from a terminal device, a computing unit, which calculates a bandwidth amount to be assigned to the terminal device based on the data amount, and a transmission unit, which sends the calculated assigned bandwidth amount to the terminal device. The transmission apparatus is characterized in that the computing unit calculates bandwidth amounts to be assigned to different types of flow of which different transmission qualities are requested according to a priority level that is set to each flow type. The transmission apparatus is also characterized in that bandwidth is controlled by designating, instead of a necessary bandwidth amount, transmission starting timing and transmission ending timing, particularly for fixed bandwidth communication data.

Abstract: A method and apparatus for estimating fiber dispersion in an optical communication system including transmitting an optical signal carrying a unique word along an optical communication path, receiving the optical signal carrying the unique word from the optical communication path, producing an electrical signal corresponding to the received unique word, and processing the electrical signal corresponding to the received unique word to produce an estimate of the fiber dispersion in the optical communication system.

Abstract: A transmitter for an optical transmission system transmits an optical sub carrier multiplexed signal comprising number of sub-carriers, onto an optical transmission path, and provides spectral shaping by different magnitudes of the sub-carriers, or different modulation formats for different sub carriers. This spectral shaping can reduce performance degradation by Kerr effect optical non linearities. This can mean higher input powers may be launched. The magnitudes can provide a signal spectrum which is lower near a center of a band of sub carriers than near an edge of the band. Such spectral shaping can be provided in the receiver either to undo the pre emphasis in the transmitter, or to reduce non linearities from components at the receiving side.

Abstract: A method for communicating in a passive optical network (PON), includes receiving traffic from a plurality of optical network units (ONUs) transmitting in an upstream transmission channel, wherein each of the ONUs may transmit at any wavelength within a wavelength band associated with the upstream transmission channel. The method also includes dividing the upstream transmission channel into a plurality of sub-channels, that each include a subset of the wavelength band associated with the upstream transmission channel. The method further includes determining the identity of each of the plurality of ONUs transmitting in each of the sub-channels, assigning a plurality of ONUs transmitting in the upstream transmission channel to each of at least two of the sub-channels based on the determination of the ONUs transmitting in that sub-channel, and allocating transmission timeslots for time-shared transmission by the ONUs in one or more of the sub-channels.

Abstract: Multi-carrier modulation fiber optic systems constructed using a series of electrical carriers, modulating the data on the electrical carriers and combining the carriers to form a wideband signal. The wideband signal can then be intensity modulated on a laser and coupled to a fiber optic channel. A receiver may then receive the laser signal from the fiber optic channel and convert it into an electrical signal. Multi-carrier modulation may be applied to existing fiber channels, which may be of lower quality. Existing fiber channels may have characteristics which prevent or restrict the transmission of data using intensity modulation at certain frequencies. An adaptive multi-carrier modulation transmitter may characterize an existing fiber optic channel and ascertain the overall characteristics of the channel. The transmitter and receiver can then be configured to use various bandwidths and various modulations in order to match the transfer characteristic of the fiber channel.

Abstract: One embodiment of the present invention relates to a method for communicating over a multi-carrier communication channel. In the method, sub-carrier frequencies that are reserved for communication between a pair of nework nodes are associated with different sub-carrier groups, where the sub-carriers of each sub-carrier group are assigned a common transmission characteristic that is independent of the transmission characteric for the other sub-carrier groups. Other methods and devices are also disclosed.

Abstract: An all optical network for optical signal traffic has at least a first ring with at least one transmitter and one receiver. The first ring includes a plurality of network nodes. At least a first add/drop broadband coupler is coupled to the first ring. The broadband coupler includes an add port and a drop port to add and drop wavelengths to and or from the first ring, a pass-through direction and an add/drop direction. The first add/drop broadband coupler is configured to minimize a pass-through loss in the first ring and is positioned on the first ring.

Abstract: An optical communication apparatus using a sub-carrier multiple access includes a laser diode for generating an optical signal with a central frequency, a temperature controller installed at a subscriber side for controlling a temperature of laser diode placed at a transmitting terminal, an optical coupler for coupling the optical signal outputted from the laser diode to an optical fiber and an optical receiver for receiving the optical signal outputted from the optical coupler. The central frequency of the optical signal outputted from the laser diode is changed in response to the change of the temperature controlled by the temperature controller.

Abstract: A real time fiber optic matrix switch includes at least one matrix switch port and a controller card. The controller card is configured to recognize communication protocols associated with any of the Type A-H and J signals of the Naval Tactical Data System (NTDS), and to enable the communication of information between the matrix switch and interconnected peripheral devices, as well as any interconnected matrix switches. The controller card is externally programmed by a digital logic program that multiplexes data streams of received signal types to one data stream, converts the multiplexed data stream to an optical signal, transmits the optical signal, receives the transmitted optical signal, transforms the received optical signal to an electric signal, demultiplexes the electric signal, validates the demultiplexed electric signal, and acknowledges the validated demultiplexed electric signal.

Abstract: A system and method for simultaneous delivery of a plurality of independent blocks of 500 MHz digital broadcast television services, stacking a plurality of RF blocks on a plurality of spectrally sliced WDM optical bands.

Abstract: This anti clipping circuit is for a laser transmitter used to transmit sub-carrier multiplexed signals for CATV applications. The circuit design is based on actual clipping measurements showing the specific time and duration of the clipping events is random. The individual clipping pulses interval is fixed, every 4 us. A PHEMT peak detection circuit is used in conjunction with a missing pulse detector/timer to catch all the clipping events. Thus the laser bias current is adjusted automatically at the specific time of the clipping event and for the duration of all the clipping pulses in the event. The controlled increase and decrease of the lasers bias current is DC coupled back into the normal DC bias path via a diode. This gives the anti clipping circuit noise isolation when there are no clipping events and avoids laser clipping during the laser current recovery time as when using an AC coupling scheme.

Abstract: A frequency modulation method is proposed that enables an imprinting of a digital message formed by a sequence of symbols on a set of frequency bands. Each symbol of the digital message is hereby assigned just one symbol value out of a defined set of symbol values. According to the method at least two symbol transmission channels are defined with each symbol transmission channel being formed by a sub-set of frequency bands selected from the set of frequency bands and with each frequency band of a symbol transmission channel being allocated to a symbol value of the set of symbol values in a one-to-one relation such, that the symbol transmission channels defined differ from each other in at least one frequency band selected and/or in an allocation of a frequency band to a symbol value. Further, each of the defined symbol transmission channels is successively modulated with a single symbol value of the digital message according to the channel allocation scheme of the respective symbol transmission channel.

Abstract: Disclosed herein is a system for providing dynamic service using optical sub-carrier multiplexing type multi-channel access and method of controlling the same. The system includes a plurality of optical sub-carrier multiplexing modems, an optical gigabit-Ethernet switch and a plurality of wavelength division multiplexing couplers. The optical sub-carrier multiplexing modems transmit user traffic using multiple optical sub-carrier channel control. The optical gigabit-Ethernet switch is connected to an access network upstream and to the optical sub-carrier multiplexing modems downstream to manage a plurality of wavelengths and a plurality of optical sub-carrier channels according to the wavelengths. The wavelength division multiplexing couplers connect the plurality of optical sub-carrier multiplexing modems with the optical gigabit-Ethernet switch, perform aggregation and branching of a certain wavelength and transmit it.

Abstract: An Ethernet passive optical network provides a subscriber with a high speed and large capacity data service and a real time digital broadcast/video service. The network includes an optical line terminal for frame-multiplexing broadcast/video signals, which are obtained by performing a switching operation and a time-slot multiplexing with respect to a plurality of digital broadcast/video data delivered from external broadcasting vendors according to broadcast/video selection information delivered from each user, and communication data delivered through an Internet protocol network.

Abstract: A photoelectric oscillator includes a laser beam projection unit; an optical modulator on an optical path extending from the projection unit, which optical modulator outputs a modulated signal or an optical signal containing a harmonic of the modulated signal and includes a modulation electrode whose resonant frequency band includes the frequency band of the modulation signal; a photoelectric converter for converting the output of the optical modulator to an electric signal; a feedback circuit for selecting from the radio-frequency electric signal obtained from the photoelectric converter an electric signal to be re-supplied to the optical modulator; and an output section for outputting an optical signal containing the modulation signal or a harmonic of the modulation signal or outputting the modulation signal or a harmonic of the modulation signal.