Abstract: Provided is a bidirectional wavelength division multiplexed passive optical network (WDM-PON) which includes a central office (CO) that transmits and receives multiplexed optical signals, a remote node (RN) that communicates with the CO, receives a multiplexed optical signal to demultiplex, and receives a demultiplexed optical signal to multiplex, an optical network unit (ONU) that transmits and receives demultiplexed optical signals to and from the RN, operational and protective backbone optical fibers that connect the CO to the RN, and operational and protective distribution optical fibers that connect the RN to the ONU.

Abstract: In a coherent optical receiver of an optical communications network, a method of recovering a clock signal from a high speed optical signal received through an optical link. A set of compensation vectors are adaptively computed for compensating Inter-symbol Interference (ISI) due to at least polarization impairments of the optical signal. A channel delay is estimated based on the computed compensation vectors. The estimated channel delay is subtracted from the computed compensation vectors to generate corresponding modified compensation vectors. Finally, the modified compensation vectors are used to derive a recovered clock signal.

Abstract: A system and method for fault identification in optical communication networks. One or more repeaters in the system includes a loop back path that couples an output a first amplifier for amplifying signals carried in a first direction through a repeater to an input of a second amplifier for amplifying signals carried in a second direction through said repeater. Fault analysis is conducted using loop gain data associated with test signals transmitted on the first or second paths and returned on the opposite path through the loop back paths.

Abstract: A tunable bidirectional multiplexer/demultiplexer (MUX/DEMUX) is disclosed for adding and dropping wavelength channels between an optical transmission system and at least one optical transceiver. The MUX/DEMUX includes at least one add port for adding wavelength channels, at least one drop port for dropping wavelength channels, and at least one first optical circulator coupled to the at least one drop port and the at least one add port. The MUX/DEMUX further includes at least one 1×N wavelength-selective switch coupled to the at least one first optical circulator, and at least one second optical circulator coupled to at least one transceiver port on a second side of the at least one wavelength-selective switch, where the optical circulators and switching components are disposed within a common housing.

Abstract: A DPSK optical receiver includes a DPSK demodulation circuit, an optical bandpass filter, a first photodetector, and a first control circuit. The DPSK demodulation circuit demodulates a DPSK optical signal and outputs the DPSK demodulated optical signal. The optical bandpass filter extracts a demodulated optical signal near the center wavelength from the DPSK demodulated optical signal output from the DPSK demodulation circuit. The first photodetector detects the optical power level of the DPSK demodulated optical signal extracted by the optical bandpass filter. The first control circuit performs phase control on the DPSK demodulation circuit so as to optimize the DPSK demodulation circuit with respect to the center wavelength of the DPSK optical signal on the basis of the optical power level detected by the first photodetector.

Abstract: There is provided an optical signal transmission apparatus having a stable dispersion compensation function without unnecessarily controlling a compensation value even when a main signal quality is deteriorated due to a factor other than dispersion or in the case of a transmission failure. When it is determined that a signal quality is deteriorated due to dispersion of a fiber by determining a control mode of a variable dispersion compensator by means of optical noise information and received power information in addition to bit error information of a received signal, a compensation value of the variable dispersion compensator is varied and a compensation value other than the dispersion of the optical fiber is held to an existing set value.

Abstract: An optical transmitter is disclosed wherein a modulating signal, such as an NRZ signal, encoding data is combined with a time derivative of the modulating signal and coupled to a directly modulated laser in order to generate artificial transient chirp in the output of the laser effective to substantially compensate for dispersion experienced by the output of the laser traveling through a dispersive medium such as an optical fiber. In some embodiments, the time derivative is added to the modulating signal only at the falling edges of the modulating signal.

Abstract: A bi-directional optical module with an improved optical crosstalk between the transmitter unit and the receiver unit is disclosed. The optical module provides the LD, the PD, the WDM filter secured with the block, and the package with the co-axial shape. The block provides a slant surface, where the WDM filter is secured thereon, the bottom surface facing the PD mounted on the package, and an aperture connecting the slant surface and the bottom surface. The PD is enclosed within a space formed by the bottom surface and the primary surface, which electrically and optically isolates the PD from the LD.

Abstract: A hermetically packaged, MEMS array-based ROADM module is disclosed. The enclosure sidewalls and a top lid are made of Kovar, and the base is made of alumina ceramic AuSn-soldered to the enclosure sidewalls. The MEMS array is attached to the ceramic base. The optics are passively pre-aligned using a removable template and epoxied to an optical bench. The optical bench is actively aligned as a whole and attached to the ceramic base. A plurality of electrical feedthrough contact pins extend from the bottom of the ceramic base for connecting the MEMS to a connector on a printed circuit board. In one embodiment of the invention, the ceramic base extends beyond the footprint of the sidewalls of the enclosure of the module, for mounting additional electronic components, for example MEMS driver circuitry chips, directly to the ceramic base of the enclosure.

Abstract: An infrared communication apparatus and method enabling data communication with a receiving device, regardless of a protocol with which the receiving device is compatible. A transmitting unit transmits a first packet to inquire whether a receiving device is compatible with a first protocol and transmits a second packet to inquire whether the receiving device is compatible with a second protocol, to the receiving device at least once, and transmits a plurality of third packets to inquire whether the receiving device is compatible with a third protocol, to the receiving device. A receiving unit receives a response packet indicating a protocol with which the receiving device is compatible, from the receiving device having received the first packet, the second packet, and the plurality of third packets. A data transmitting unit transmits data to the receiving device, based on the protocol indicated by the response packet received by the receiving unit.

Abstract: An optical transmitting apparatus includes a modulating unit that branches an input light and performs independent phase modulation to branched optical signals of arms, a phase adjusting unit that changes a phase difference between the optical signals of respective arms according to a control signal, a combining unit that combines modulated lights having the phase difference, an acquiring unit that acquires a positive-phase signal and a negative-phase signal from the combining unit, a subtracting unit that obtains a difference between the positive-phase signal and the negative-phase signal acquired by the acquiring unit, a detecting unit detecting a power of a differential signal from subtraction by the subtracting unit, and a control unit that changes the control signal according to signal component intensity detected by the detecting unit.

Abstract: An all-optical carrier sense multiple access collision detection apparatus and method for checking by using mutual gain saturation whether distortion occurs in two or more optical signals due to mutual interference when the optical signals pass through a semiconductor optical amplifier.

Abstract: A signal receiver, such as an RF-matched filter receiver, includes an optical source (e.g. a mode-locked laser) providing an optical signal, and a first optical modulator to modulate the optical signal with a received RF signal and provide a modulated optical signal. A second optical modulator modulates the modulated optical signal with a reference signal and provides a twice modulated optical signal. The modulators may be Mach-Zehnder Modulators (MZM) and/or Indium Phosphide (InP) modulators. An optical detector receives the twice modulated optical signal and provides a detected signal, and a processing unit receives the detected signal and extracts or measures cross-correlation between the received RF signal and the reference signal.

Abstract: A method for monitoring wavelength-division multiplexed (WDM) signal for detecting signal drift of objective signals, including generation of one or more objective signals and a guard signal. The guard signal has a wavelength that is within a range defined by a guard channel. The first and second objective signals and the guard signal are wavelength-division multiplexed to generate a wavelength-division multiplexed signal. The first objective signal, the second objective signal, and the guard signal are assigned to a first multiplexed objective channel, a second multiplexed objective channel, and a multiplexed guard channel, respectively. The wavelength-division multiplexed signal is received by a monitor and then the error rate of the multiplexed guard channel is determined.

Abstract: Optical test apparatus. A test apparatus for testing transmitter or receiver devices. The test apparatus includes a transmitter source configured to connect to an optical transmitter. A wide band, wide area optical detector is adapted to optically couple to the optical transmitter powered by the transmitter source. A filter is connected to the optical detector. The filter is configured to separate AC and DC portions of a signal received from the optical detector. A true RMS converter is connected to the filter. The filter is configured to convert an AC noise signal received from the filter to a function of an RMS value of the AC noise signal received from the optical detector. A data acquisition system is connected to the true RMS converter. The data acquisition system is configured to characterize noise characteristics of the transmitter source.

Abstract: A phase-modulated analog optical link that uses parallel interferometric demodulation to mitigate the dominant intermodulation distortion present in the link. A receiver for demodulating phase modulated optical signals includes a splitter dividing the phase modulated signal into parallel optical paths, each optical path having an asymmetrical interferometer, the time delays of the interferometers being unequal, and each optical path includes a photodiode optically connected to an output of the interferometer. Outputs of the photodiodes enter a hybrid coupler. Alternatively, outputs of the interferometer enter a balanced photodetector. A phase shifter or time delay element can be included in one optical path to ensure inputs to the coupler or balanced photodetector have the correct phase. The input power to the parallel optical paths is split in a ratio that balances the third-order distortion in the output photocurrent.

Abstract: An optical transmitting and receiving apparatus 1 has a transmitting circuit unit 20 including a light emitting element 2 and a driving circuit 3 which drives the light emitting element 2, a receiving circuit unit 30 including a light receiving element 5 and amplification circuit 6 which amplifies a signal received from the light receiving element 5, a judging unit 8 which judges an abnormality or failure of either or both of the transmitting circuit unit 20 and the receiving circuit unit 30 based on a measured data value provided from the transmitting circuit unit 20 and/or the receiving circuit unit 30, and a measured value storing unit 9 which stores the measure data value in the case that the judging unit 8 judges the abnormality or failure occurs in the transmitting circuit unit 20 and/or the receiving circuit unit 30.

Abstract: Provided is an optical interconnection system that transmits and receives a three-level signal. The optical interconnection system includes a first and a second optical interconnection device that transmits and receives a two-level signal, and a synthesizer that outputs a three-level signal by synthesizing signals from the first and second optical interconnection devices. The optical interconnection system may transmit and receive a three-level signal while using an optical interconnection device that interconnects a two-level signal.

Abstract: A method and corresponding apparatus for diagnosing problems on a time division multiple access (TDMA) optical distribution network (ODN) is provided. An example method may include: (i) measuring no-input signal power level on a communications path configured to carry upstream communications between multiple optical network terminals (ONTs) and an optical line terminal (OLT) in a passive optical network (PON) at a time no upstream communications are on the communications path from the ONTs to the OLT; (ii) comparing the measured no-input signal power level to a threshold; and (iii) generating a notification in an event the threshold is exceeded. Through the use of this method, faults in optical transmitters, such as bad solder joints, can be determined. Such faults may cause errors in parameters, such as ranging or normalization parameters, associated with communications. By determining the faults, the time required to resolve communications errors can be reduced.

Abstract: According to an aspect of an embodiment, an apparatus includes: a wavelength-to-transmission quality characteristic obtaining unit for obtaining a wavelength-to-transmission quality characteristic; a residual dispersion-to-transmission quality characteristic saving unit for saving a residual dispersion-to-transmission quality characteristic; a wavelength-to-residual dispersion characteristic generating unit for generating a wavelength-to-residual dispersion characteristic from a relationship between the wavelengths of the other channels and the residual dispersion based on the wavelength-to-transmission quality characteristic and the residual dispersion-to-transmission quality characteristic; a variable dispersion compensator for providing variable dispersion compensation to another channel,; and a variable dispersion compensation controlling unit for performing setting control on a dispersion compensation amount.