Abstract: A distortion compensating apparatus which compensates for distortion in a waveform of a received light signal through a digital signal processing includes a plurality of fixed amount compensators which compensate for the distortion in the waveform at respective given compensating amounts. The combination of operating states of the plurality of fixed amount compensators is changed by on/off switching of each of the plurality of fixed amount compensators, and the plurality of fixed amount compensators are cascaded.

Abstract: Disclosed are an optical signal concentrator and an optical receiver for wireless optical communication. The concentrator includes a diffusion sheet and a light guide plate positioned below the diffusion sheet for guiding diffused optical signals perpendicularly to the incident direction the diffused optical signals, the light guide plate being formed with at least one concentric circle pattern facing the diffusion sheet. The receiver includes an optical signal concentrator including a diffusion sheet, a light guide plate positioned below the diffusion sheet for guiding the optical signals perpendicularly to the incident direction the diffused optical signals, one or more optical detectors for detecting light projected to the side of the light guide plate, and a reflection plate for reflecting light incident to the light guide plate.

Abstract: Methods and devices for detecting at least one first input signal superimposed on at least one second signal. The method comprises the steps of providing said at least one first input signal superimposed on at least one second signal to at least one half-wave rectifier; transforming, in said at least one half-wave rectifier, said at least one first input signal superimposed on at least one second signal into a half-wave rectified signal; providing said half-wave rectified signal to an envelope detector; and transforming, in said envelope detector, said half-wave rectified signal into an envelope signal and wherein the at least one half-wave rectifier comprises at least one optoelectronic device. In this way, a simpler and cheaper method and/or device are provided for e.g. detecting a transmitted information signal superimposed on a high frequency carrier signal.

Abstract: A bandwidth allocation and management system for cellular communication networks. The system includes at least one master optical switch and processing station, a number of aggregation base stations that are in optical fiber communication with a master optical switching and processing station and a number of auxiliary cellular base stations surrounded by and supported by each aggregation base station. In preferred embodiments a plurality of sets of three neighboring base stations are each adapted to receive and process RF signals transmitted by cellular users within a broadcast and receive range and transmit the RF signals received, by each of the three neighborhood base stations, from each of the cellular users in analog form to the master optical switching and processing station.

Abstract: There is provided an optical transmission apparatus including: a plurality of wavelength selective switches including input ports, a transmission port, and monitor port used to output a light switched so that the light from the input port is monitored; a multiplexer to combine the lights output from the transmission ports of the plurality of wavelength selective switches; a monitor to monitor whether a same wavelength of the light output from the monitor port exists in wavelengths of the lights combined by the multiplexer; and a controller to control the wavelength selective switch so as to output, from the transmission port, the light switched to the monitor port in case that the same wavelength of the light output from the monitor port is absent in wavelengths of the lights combined by the multiplexer, based on a monitor result by the monitor.

Abstract: A data transmission method for transmitting a digital optical signal over an optical transmission link includes creating a digital optical signal defining at least two service levels, each service level transporting information via a modulation scheme comprising at least three different modulation symbols. The data transmission method also includes transmitting the digital optical signal over the transmission link and receiving the transmitted digital optical signal at a remote end of the transmission link by demodulating the received signal and extracting the information of the at least two service levels. In case that the transmission performance is below a given threshold due to increased constraints of the transmission link a compensating action is taken to drop at least one of the service levels from the optical signal or to determine parameters associated with the transmission so as to increase one of the service levels to a predetermined quality level.

Abstract: While altering a plurality of wavelength setting parameters according to a control sequence, a local oscillation light having a wavelength controlled by those wavelength setting parameters is generated. Further, the received signal light and the generated local oscillation light are mixed, and if an electric signal is generated by photoelectric conversion from the resulting light, then the wavelength control of the local oscillation light is terminated.

Abstract: An optical transmission system having an optical source, an optical dispersion compensation filter optically connected to the optical source, and a control system. The optical source generates a modulated optical signal having an optical spectrum and a value of dispersion robustness. The optical dispersion compensation filter has at least two cascaded optical resonators and a periodic transfer function rigidly translatable in the frequency spectrum to obtain translation in frequency of the transfer function without a substantial change in shape, and characterized by a free spectral range. The control system acts on the optical dispersion compensation filter in order to rigidly translate the transfer function along the frequency spectrum in first and second positions in the frequency spectrum. The translation of the transfer function between the first and the second positions is smaller than the free spectral range.

Abstract: A representative optical receiver of the invention receives an optical transverse-mode-multiplexed (TMM) signal through a multimode fiber that supports a plurality of transverse modes. The optical receiver has a plurality of optical detectors operatively coupled to a digital signal processor configured to process the TMM signal to determine its modal composition. Based on the determined modal composition, the optical receiver demodulates each of the independently modulated components of the TMM signal to recover the data encoded onto the TMM signal at the remote transmitter.

Abstract: A method and system for encoding and determining labels in a Dual Polarization (DP) Quaternary Phase Shift Keying (QPSK) signal is provided. A label frame, signature sequence, and data payload are combined using a complementary constant-weight code encoding (CCWC) encoder, the output of which is deinterleaved and differentially precoded to generate a polarized tributary of a DP-QPSK signal. This encoding can be duplicated for a second tributary of the DP-QPSK signal. The label can be determined using one or more polarizers and corresponding low-speed photodetectors, each applied to a copy of the DP-QPSK signal. The strongest output of the photodetectors is then used to determine the label. Alternatively, the DP-QPSK signal can be viewed as having XI, XQ, PH, and PV tributaries. These tributaries can then be translated into XI, XQ, YI, and YQ tributaries are encoded into a standard DP-QPSK signal.

Abstract: A method for providing access to a passive optical network for services to homes or businesses from two or more telecommunications service providers and a billing means is described. A first service provider connects to a point of presence at one side of passive optical network. The provider transmits the appropriate services through this network to an authorization receiver. The authorization receiver is used to receive a periodic authorization code from the network provider to enable the appropriate services from the service provider to be transmitted to a subscriber at a home or business. The authorization receiver enables an optical fiber path to be established for the services to flow to and from the home or business.

Abstract: An optical communication system having an optical transmitter and an optical receiver optically coupled via a multi-path fiber. The optical transmitter launches, into the multi-path fiber, an optical transverse-mode-multiplexed (TMM) signal having a plurality of independently modulated components by coupling each independently modulated component into a respective transverse mode of the multi-path fiber. The TMM signal undergoes inter-mode mixing in the multi-path fiber before being received by the optical receiver. The optical receiver processes the received TMM signal to reverse the effects of inter-mode mixing and recover the data carried by each of the independently modulated components.

Abstract: Provided is a high power efficiency optical-wireless transmitter capable of solving problems of low power efficiency, signal distortion due to non-linearity of output, large number of connection terminals, and non-uniformity of optical power intensities of optical sources. The high power efficiency optical wireless transmitter includes: an amplitude-to-array coder converting an amplitude of an electric signal input from a baseband modulator into optical source control signals so as to generate an optical output power corresponding to the electric signal; optical source driver groups driving optical sources based on the optical source control signals of the amplitude-to-array coder; and MMRS (modified mixed radix system) or MMRR (modified mixed radix system with Redundancy) optical source group driven by the optical source driver groups to generate various optical power intensities.

Abstract: A method for locating fiber events and an optical network and network device are provided. The method for locating fiber events includes: determining the distance between an event and an OLT, measuring the optical loss of the optical channel between the OLT and an ONU or ONT at the peer end of the measured fiber link, and, according to the measured optical loss of the optical channel, judging whether the event occurs on the measured fiber link, and if so, determining the location of the event on the measured fiber link according to the distance between the event and the OLT.

Abstract: An optical transmission apparatus connected to an optical ring network stores identification information of an optical transmission apparatus as a communication partner predetermined on a communication path. Each optical transmission apparatus includes self identification information in header information of an optical signal having a working wavelength used in normal operation, and transmits the optical signal to one of the two optical ring networks transferring optical signals in mutually opposite directions. The optical transmission apparatus determines whether the identification information included in the header information of the received optical signal having the working wavelength matches pre-stored identification information. The optical transmission apparatus thus detects a fault that occurs by the communication path.

Abstract: The present disclosure provides optical communication systems and methods that utilize, on top or in place of the conventional framework: (1) optical amplifiers that are provided with extended bandwidth coverage, such as Extended Band Erbium-Doped Fiber Amplifiers (EDFAs), combination of Raman amplifiers and EDFAs, Split-Band C+L EDFAs, etc.

Abstract: A method for reducing cross-phase modulation in an optical signal includes receiving an optical signal comprising a plurality of channels, wherein the information being communicated in a first set of one or more of the channels is modulated using one or more single-polarization modulation techniques and wherein the information being communicated in a second set of one or more of the channels is modulated using one or more dual-polarization modulation techniques. The method also includes splitting the optical signal into at least a first copy of the optical signal and a second copy of the optical signal and terminating the second set of channels in the first copy. Furthermore, the method includes applying a differential group delay to the second copy, the differential group delay introducing a walk-off between symbols communicated in a first polarization component of the second set of channels and the symbols of a second polarization component of the second set of channels.

Abstract: A method for the polarization independent frequency domain equalization (FDE) on polarization multiplexing (POLMUX) coherent systems employing an adaptive crossing FDE which advantageously produces CD compensation, PMD compensation and PolDeMux within one functional block of a digital signal processor (DSP).

Abstract: A method for the polarization independent frequency domain equalization (FDE) chromatic dispersion compensation on polarization multiplexing (POLMUX) coherent systems. Operationally, time domain signals are converted to frequency domain signals such that time domain convolution can be done as simple multiplications in the frequency domain. These frequency domain signals then converted back to time domain for subsequent use. The input signal size and FFT size are advantageously designed so that the output signals can be continuous with some overlap between two successive frames.

Abstract: Digital compensation of chromatic dispersion (CD) effect experienced by optical orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission is provided in the frequency domain using a Fast Fourier Transform/Inverse Fast Fourier Transform (FFT/IFFT) pair with equal length of digital samples prior to OFDM receiver signal processing, wherein the equal length is larger than the length of a FFT used for OFDM subcarrier demultiplexing of the received signal. The OFDM signal processing is independent of fiber CD, so small guard-interval (GI) can still be used to achieve high spectral efficiency even under the experience of large CD. The GI need only to be large enough to accommodate other effects such as polarization-mode dispersion.