Abstract: A dispersion compensating method for compensating wavelength dispersion occurring in an optical transmission line, includes the steps of: a) performing dispersion compensation by causing an optical signal, supplied from the transmission line, to pass through a variable dispersion compensator; and b) controlling a dispersion compensating amount in the variable dispersion compensator according to code error information corresponding to a type of code in a received data signal obtained from receiving the optical signal having undergone the dispersion compensation.

Abstract: The present invention relates to a light source apparatus. The light source apparatus includes a plurality of optical pulse train generation sections; an optical switch section capable of selectively outputting an optical pulse train to be taken as an optical pulse train for current use; an output light generation section capable of generating continuous light of multiple wavelengths from said optical pulse train output from said optical switch section; and an optical switch control section for controlling said optical switch section to switch an output of said optical pulse train for current use from said optical switch section, in accordance with the states of respective optical pulse trains generated by said plurality of optical pulse train generation sections and without involvement of instantaneous power interruption.

Abstract: An optical transmission system includes an optical signal transmitter to output optical signal, a monitoring light transmitter to generate monitoring light, an optical multiplexer to output a multiplexed signal light by multiplexing the optical signal and monitoring light, an optical relay transmission path to amplify the multiplexed signal light by using a Raman amplification effect, an optical demultiplexer to demultiplex the multiplexed signal light, a monitoring light receiver to receive the monitoring light output from the optical demultiplexer, and a pumping light source stopping device to continuously monitor a transmission state of the monitoring light and, when the transmission of the monitoring light is interrupted, to stop emission of the pumping light from the pumping light source to be used for distributed Raman amplification.

Abstract: In an optical signal transmission system which can perform high-speed optical transmission not lower than 1 Gbps, VCSEL has light-emission points. A core diameter of an optical fiber GI-POF is set to not lower than 200 ?m, and the light-emission points of VCSEL are arranged inside an outer periphery at an end face of GI-POF. A polymerization composition material constituting the core of GI-POF is made of a compound containing deuterated poly methacrylic ester. A wavelength of the light beam of VCSEL is set to the range of 770 nm to 810 nm.

Abstract: An optical control monitor and a method for adjusting for changes in optical signals transmitted through an optical network. The method comprises the steps of transmitting a set of optical signals through a network, each of the optical signals having a respective wavelength; and tracking changes to said set of signals by passing each of the signals through a filter having a bandpass function, and dithering the filter bandpass about the wavelengths of each of said set of signals to generate filter output signals. The filter output signals are used to adjust the network or the set of optical signals to compensate for said changes.

Abstract: In a data multiplexing network system, a first wavelength multiplexing function unit sets a plurality of different wavelengths which correspond to a plurality of different service classes, respectively, and maps each packet into each correspondent-wavelength which corresponds to each service class, to which the each packet belongs, and multiplexes the correspondent-wavelengths for the plurality of different service classes for a data transmission at a multiplexed-wavelength through a wavelength division multiplexing network. A second wavelength multiplexing function unit receives the each correspondent-wavelength and fetches a packet from the each correspondent-wavelength.

Abstract: Systems, devices and methods for transmitting and receiving signals on an optical network are disclosed. In one aspect, a micro device for connecting an electronic device to an optical transmission system is disclosed. The micro device can comprise optical components for receiving optical signals and converting the optical signals to electrical signals, a phase shifter for controlling the phase of the electrical signals, and an attenuator for controlling power level of the electrical signals, wherein the micro device is of a size having low electromagnetic interference susceptibility and emissivity.

Abstract: A system and method for providing two-way communication of quantum signals, timing signals, and public data is provided. Generally, the system contains a first public data transceiver capable of transmitting and receiving public data in accordance with a predefined timing sequence, a first optical modulator/demodulator capable of transmitting and receiving timing signals in accordance with the predefined timing sequence, a first quantum transceiver capable of transmitting and receiving quantum signals in accordance with the predefined timing sequence, and a first controller connected to the first public data transceiver, the first optical modulator/demodulator, and the first quantum transceiver. The first controller is capable of controlling the transmission of the public data, the timing signals, and the quantum signals in accordance with the predefined timing sequence.

Abstract: A free-space adaptive optical laser communication system having signal transmission and reception channels at all terminals in the communication system, wherein wavefront sensing and wavefront correction mechanisms are employed along signal transmission and reception channels of all terminals in the communication system (i.e. adaptive optics) to improve the condition of the laser beam at the receiver (i.e. reduce the size of the spot the detector plane). Speckle-to-receiver-aperture tracking mechanisms are employed in the transmission channel of the communication system and laser beam speckle tracking mechanism in the reception channels thereof, so as to achieve a first level of optical signal intensity stabilization at signal detector of each receiving channel.

Abstract: Provided are a plurality of fixed wavelength drop filters 35 demultiplexing optical signals having a plurality of different fixed wavelengths, a plurality of fixed wavelength add filters 36 provided corresponding respectively to the fixed wavelength drop filters 35 and adding the optical signals having the fixed wavelengths wavelength division multiplexed light flowing along a transmission path 1, a first optical branching unit 31 branching part of the wavelength division multiplexed light flowing along the transmission path 1, and a variable wavelength drop filter 32 demultiplexing the optical signal having the wavelength corresponding to a specified value from the wavelength division multiplexed light branched by the first optical branching unit 31.

Abstract: Efficient systems, devices, apparatus and methods to generate, transmit and detect differentially encoded 8-level phase-modulated optical signals for spectrally efficient optical communication systems is invented. It includes an electrical encoder and an optical encoder for generation of differentially encoded 8-level phase-modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or air. The electrical encoder maps three independent data channels into three differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded 8-level phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel.

Abstract: A method of, and an apparatus for, biasing photodiodes used in optical receivers or optical transceivers includes an electronic circuit for generating a bias voltage for the photodiode and a processor having a pulse-width modulation unit that produces pulse-width modulated pulses at a predetermined number of duty cycle values M. The processor is coupled to the electronic circuit such that a magnitude of the bias voltage is dependent upon a duty cycle value of at least one of the pulse-width modulated pulses. Advantageously, the processor includes a program for modulating the pulse-width modulated pulses generated by the processor between two different duty cycle values such that a number of obtainable bias voltages is greater than M. The result is a significant reduction in the number of necessary components.

Abstract: The invention, in one form, is a fiber optic system having an optical signal source adapted to produce a frequency and amplitude modulated optical digital signal and a semiconductor optical amplifier adapted to receive the frequency and amplitude modulated optical digital signal and generate negative transient chirp at the transitions between bits. In another form, the invention is a fiber optic system having an optical source adapted to generate a frequency modulated signal, a semiconductor optical amplifier adapted to receive and amplify the frequency modulated signal, and an optical spectrum reshaper adapted to receive the amplified frequency modulated signal and to utilize the amplified frequency modulated signal to increase the amplitude modulation of the signal.

Abstract: In a representative embodiment, a transmitter of a WDM communication system is equipped with a Mach-Zehnder modulator (MZM) configured to produce an optical signal corresponding to a duobinary data stream by modulating a beam of light passing through the MZM. A three-level electrical signal is applied to the MZM to modulate the light. At the second signal level, the modulator substantially blocks light transmission. At the first and third levels, the modulator transmits light corresponding to the duobinary “?1” and “+1” bits, respectively, such that a relative phase shift between the optical bits is different than 180 degrees, i.e., the phase shift value employed in prior-art optical duobinary modulation.

Abstract: This digital transmission system is provided with a transmitting apparatus that transmits digital data signals and a receiving apparatus that receives the digital data signals transmitted over a transmission path, compares the signals with a predetermined threshold value, and performs decision reproduction. The receiving apparatus is formed by: decision circuits that receive the input of reception signals, discriminate between the respective reception signals using a plurality of threshold values, and output decision results; and a selection circuit that, based on the decision results output from the decision circuit, selects one decision result from one threshold value from among the decision results from each of the plurality of threshold values, and outputs the selected decision result. As a result, the receiving apparatus is able to individually select which decision result to use from which threshold value.

Abstract: A control device with a switchable bandwidth including: an integrating element with a first capacitance, which is charged and discharged by at least one current; at least one second capacitance, which can be connected in parallel with the first capacitance via a first switch; and at least one voltage follower, via which the voltage present at the first capacitance can be fed to the second capacitance. In this case, the first switch is open if the voltage present at the first capacitance is fed to the second capacitance by means of the voltage follower. The first switch is closed if the second capacitance is connected in parallel with the first capacitance. The invention enables a further capacitance to be supplementarily connected without a disturbance signal arising.

Abstract: A method of determining a transmission route for optical signals in an optical signal transmission system comprising a transmitter for optical signals, a receiver for the optical signals, and repeaters for repeating the optical signals transmitted from the transmitter to the receiver, and having transmission routes between the transmitter and the receiver, wherein the numbers of the wavelength components of the optical signals that has been in-use in each section defined to each of the transmission routes, the acquired numbers of wavelength components are compared among the transmission routes, and one of the transmission routes having the minimum number of wavelength components is determined as the transmission route used to set the line.

Abstract: An object of the invention is to provide a diagnosis method for standby systems in an optical ring network having a redundant configuration, which can confirm normal states of standby systems in all optical transmission apparatuses on the network, even during operations of active systems. To this end, in the present diagnosis method for standby systems, when a diagnosis start command is given to an arbitrary optical transmission apparatus on the network, the optical transmission apparatus provides a false signal to a standby system unit to diagnoses an operation state thereof, and transmits the result to the optical transmission apparatus on the downstream side by utilizing overhead information in the active system optical channel.

Abstract: An optical spread spectrum communication system includes a tunable laser which sequentially outputs optical signals having different wavelengths. The laser produces a frequency spectrum having a plurality of closely spaced modes relative to optical frequencies. The system further includes an optical modulator and a frequency synthesizer. The frequency synthesizer controls the optical modulator to allow specific modes from the frequency spectrum to pass through. Additionally, the system includes a tunable filter and a phase locked loop (PLL) control circuit. The PLL control circuit controls the filter to select specific channels. The selection of the specific modes by the modulator and the selection of channels by the tunable filter are performed independent of each other and are based on randomly assigned codes generated in accordance with one or more algorithms.

Abstract: A method and apparatus for transmission of optical signals across an optical transmission link wherein duobinary signals or inverse-data signals are transmitted when the chromatic dispersion of the transmission link is above or below a dispersion threshold, respectively, to significantly improve optical signal transmission performance.