Abstract: The invention provides an optical signal transmitter low in noise and in distortion and provides an optical signal transmission system using this optical signal transmitter. The optical signal transmitter includes a plurality of frequency modulation means for distributing an electric signal into a plurality of electric signals and applying frequency modulation to the distributed electric signals to output and a multiplexing mean for multiplexing a plurality of signals output from the plurality of frequency modulation means and outputting a multiplexed signal. The plurality of frequency modulation means are set to be substantially equal to each other in frequency deviation and in intermediate frequency and to be substantially identical to each other in the phase of each output.

Abstract: The dispersion monitoring device of the present invention detects a change in dispersion caused in a system by performing the decision process of a received signal using a data flip-flop in which required decision phase and decision threshold are set, averaging the output signal of the data flip-flop using an integration circuit and determining a received waveform, based on a change in a level of an output signal from the integration circuit. In another preferred embodiment, a signal is inputted to a chromatic dispersion change sign monitor. If a chirping parameter is correctly set, residual chromatic dispersion shifts in the negative direction when the peak value of a received signal is large, and it shifts in the positive direction when the peak value of a received signal is small. Using this fact, optimum dispersion compensation is conducted.

Abstract: In optical wireless networks, light beams are transmitted over-the-air and maximum performance is achieved when light beams are aligned with corresponding light detectors. A feedback control system is created between transmitting and receiving units, wherein the receiving unit provides positional data about the light beam from the transmitting unit. The transmitting unit uses the data provided to make adjustments to its light beam. However, in order to use the positional data, the units must be operating with a common coordinate basis. A method is provided for determining the basis and generating the transformation needed to modify positional data from one unit into information that is useful for the other unit. Additionally, a method is presented for using the positional data to maintain proper alignment of the light beam.

Abstract: Optical communication apparatuses and optical communication methods are provided. According to one aspect, an optical communication apparatus includes a communication path configured to communicate a first signal; a signal generator configured to provide a second signal; a combiner configured to combine the first signal with the second signal to provide a composite signal; and a light source coupled with the combiner and configured to receive the composite signal and to output an optical signal corresponding to the composite signal to an optical conduit, wherein the signal generator is configured to monitor the application of the optical signal to the optical conduit and to alter the second signal responsive to the monitoring.

Abstract: A method and apparatus are provided for measuring samples of the electric field of light propagated through a device under test and determining a nonlinear property of the device, such as self-phase modulation or cross phase modulation, using the measured samples.

Abstract: An Ethernet-PON integrates broadcast/communication through time division multiplexing, which provides users with high-speed, high-volume communication data and high-quality, real-time digital broadcast/image data. An OLT performs a switching operation on a plurality of digital broadcast/image data received from an external broadcaster according to respective broadcast/image selection information from users, time-division-multiplexes the data into a broadcast/image signal, multiplexes the signal and communication data from an IP network into a frame, and electro-optically converts the frame and transmits to the frame to ONTs through an optical splitter. Each ONT receives and photoelectrically converts the signal from the OLT, and performs frame & time-slot demultiplexing to output the entire received communication signals and broadcast/image information contained in a time-slot assigned to the ONT to a corresponding user.

Abstract: An optical device extracts an information bearing sideband such as an FSK or SCM signal (label) from a composite signal that includes the sideband and an orthogonally modulated signal such as an intensity modulated signal (payload) by employing polarization beam splitting and polarization transformation. Polarization transformation is accomplished by splicing the optical signal into a polarization maintaining fiber at a desired angle so that it is separated into two orthogonal polarizations that experience differential group delay in the fiber. The fiber is characterized by a beat length Lbeat and the fiber is designed to have a length substantially equal to (Lbeat×fc)/2?f, wherein the sidebands of the composite signal are separated by a wavelength difference ?f and fc is the nominal center frequency of the composite signal. This device has been shown to be useful for extracting GMPLS LSC level wavelength labels from either an FSK/IM composite signal or an SCM/IM composite signal.

Abstract: A method and apparatus to accommodate differing output loads without sacrificing impedance matching in an optical modulator driver.

Abstract: Provided is a burst mode optical receiver considering a characteristic of an extinction ratio of a received optical signal is provided. By using a peak detector considering a characteristic of an extinction ratio, top and bottom peak voltages of actual burst packets can be precisely detected while not being affected by a DC offset corresponding to an extinction ratio even though burst packets having a DC offset corresponding to the extinction ratio are received. Accordingly, waveform distortion of a signal output from the burst mode optical receiver can be minimized.

Abstract: A bi-directional optical transceiver module includes an optical transmitter, and an optical receiver, which have a TO-can structure, and generates a first optical signal and detects a second optical signal, respectively. A housing includes a first receiving section that receives the optical transmitter. A second receiving section is arranged opposite the first receiving section, a third receiving section is arranged below the first and second receiving sections, and a fourth receiving section is arranged opposite the third receiving section. The receiving stations communicate through holes between the first through fourth receiving sections. An optical fiber ferrule in the second receiving section supports an optical fiber to input the second optical signal into the bi-directional optical transceiver module.

Abstract: To optimize the resources of an optical transmission network using wavelength division multiplexing, assigning carrier frequencies to signals to be transmitted consists in associating N sets of optical frequencies of the comb with N respective ranges of consecutive error rate values, each of the sets comprising frequencies generating a mean error rate in the associated range, defining a measured signal transmission constraint level that is a function of the transmission constraint parameter(s) and may take N distinct values referred to as constraint values, associating the N constraint values in increasing order respectively with the N sets of frequencies in decreasing order of the error rate values of the associated N ranges, assigning any signal to be transmitted a constraint value obtained by applying the measurement, and assigning the signal to be transmitted a carrier frequency belonging to one of the sets of frequencies that is associated with a constraint value at least equal to the constraint value as

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 wavelength stabilizing filter has a wavelength transmission characteristic curve that has its peak in a wavelength located between a first continuous set band and a second continuous set band longer in wavelength than the first set band, and that linearly drops from the peak toward the shorter wavelength side than the first set band and also toward the longer wavelength side longer than the second set band. A control unit generates a control signal needed to enable an optical tunable filter to extract signal light with a predetermined wavelength from an inputted WDM signal, based on light transmitted through the wavelength stabilizing filter.

Abstract: The method for operating an optical transponder, which performs maintenance of a signal in the optical transponder having a digital wrapper in an optical transmission system including multiple layers, includes (a) calling a processor for processing an interrupt when the interrupt is generated from the digital wrapper according to monitoring of a received signal; (b) the called processor detecting what defect is generated in the received signal and detecting whether or not the received signal requires maintenance; (c) performing defect processing in the case that a defect is detected at (b) or is cancelled; and (d) controlling the digital wrapper according to the defect and maintenance processing result.

Abstract: A tool for static or dynamic planning of a WDM network with dedicated protection. The WDM network is represented by a layered graph having image nodes for each node of the network and horizontal arcs for each link of the network, so as to replicate in each layer the topology of the network. A Bhandari algorithm is adapted for finding on the layered graph a working-spare pair of lightpaths for each connection request to be allocated.

Abstract: An optical transmitter for sending supervisory data signals and line data signals as a composite optical signal through an optical fiber link is disclosed. The transmitter may take the form of a transmitter, transceiver or transponder and includes circuitry for receiving incoming line data bit rate information for varying and or controlling the modulation index by varying the supervisory carrier frequency amplitude in dependence upon the line data bit rate.

Abstract: An infrared transmitter circuit causes an output current to flow to a light emission diode via a current mirror circuit constituted of three transistors by using a current supplied from a power source circuit, so that the light emission diode emits light. When a voltage V1 varied by charging a capacitor with a current flowing from the power source circuit exceeds a reference voltage (voltage V2), an output of a comparator resets a D flip-flop, so that an output of the D flip-flop varies to “0”. Thus, an output of a NAND gate to which that output and a transmission signal are inputted causes a transistor (N-channel FET) to turn ON so as to stop operation of the current mirror circuit, and causes a transistor (P-channel FET) to turn OFF so as to cut a connection between the power source circuit and a power source line. Thus, it is possible to reduce power consumption in operation of a protection circuit which stops supplying the output current to the light emission diode.

Abstract: A self-healing passive optical network is disclosed. The network includes a central office and a remote node connected to the central office through a main optical fiber. The remote node transmits one portion of power of the upstream optical signal, which has been input from each of the optical network units, to the central office, and returning a remaining portion of the power of the upstream optical signal to the optical network unit. The network also includes a plurality of optical network units connected to the remote node through a plurality of distribution optical fibers. Each of the optical network units transmits an upstream optical signal to the remote node through the directly connected distribution optical fiber, and detects abnormality occurrences from a state of the upstream optical signal returning from the remote node.

Abstract: An optical source generator for wavelength-division-multiplexing optical communication systems includes a wavelength-division multiplexer/demultiplexer, optical amplifiers, and wavelength-dependent reflectors such as optical fiber-Bragg gratings or wavelength-independent reflectors such as mirrors, so as to form laser resonant cavities. Lasing of the optical fibers therefore generates spontaneously emitted lights. Further, the optical source generator controls each reflectance of the respective wavelength-dependent or independent reflectors so that lights amplified within the laser resonant cavities can be used as multi-wavelength optical sources or independent optical sources.

Abstract: A device and method for multiplexing or demultiplexing M optical signals, each having a different wavelength ?m. An MMI waveguide has a length such that each optical signal that propagates into the MMI waveguide at an i:th access waveguide, where i?N, and N is greater than or equal to 2, produces N self-images inside the MMI waveguide at a respective distance Im from the access waveguides. Each of M wavelength selective reflectors is arranged near a respective distance Im, wherein the m:th reflector reflects the optical signal carried by the m:th wavelength, where 2?m?M, while being substantially transparent to all other wavelengths. Each of M phase adjustors is arranged relative to a corresponding reflector, wherein the m:th phase adjustor adjusts the phase of the self-images of the optical signal carried by the m:th wavelength to create a single self-image at a selected output access waveguide when reflected by the m:th reflector.