Abstract: A method for measuring a response from an optical fiber providing distributed back reflections using a system comprising an optical source comprising a laser, an optical receiver and a processing unit is disclosed. The method comprises generating an interrogation signal and an optical local oscillator using the optical source, the interrogation signal being represented by an interrogation phasor and the optical local oscillator being represented by a local oscillator phasor; transmitting the interrogation signal into the optical fiber; and mixing the optical local oscillator with reflected light from the optical fiber and detecting a mixing product with the optical receiver to achieve a receiver output signal.

Abstract: A fibre-optic hydrophone comprising a substantially incompressible tubular body, the tubular body generally having a geometry of a cylindrical shell defining an axis, and a deflectable outer wall, arranged to surround the tubular body in a distance thereof, and defining an axis that is arranged to substantially coincide with the axis of the tubular body. The hydrophone further comprising an optical fibre coil arranged on an outer surface of the outer wall, and a first and a second end lid arranged to seal the tubular body and the outer wall at a first end and a second end thereof, respectively, the first end lid and the second end lid being substantially incompressible. Additionally, the hydrophone comprising an outer cavity defined by an inner surface of the outer wall, an outer surface of the tubular body, the first lid, and the second lid; and an inner cavity defined by an inner surface of the tubular body, the first lid, and the second lid.

Abstract: Various example embodiments for supporting supervision in optical communication systems are presented. Various example embodiments for supporting supervision in optical communication systems may be configured to support supervision of an optical path including a remote optically pumped amplifier (ROPA) and, thus, supervision of the ROPA. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical supervisory paths configured to extract a pair of optical supervisory signals from an optical path in a first direction and to insert the pair of optical supervisory signals into an optical path in a second direction. Various example embodiments for supporting supervision of an optical path including a ROPA may be configured to support supervision of the optical path including the ROPA based on a pair of optical time-domain reflectometer (OTDR) paths.

Abstract: An automated system for coiling a large (e.g., >1000 km) length of cable in a cable tank. In an example embodiment, the system comprises a gantry positioned above the cable tank and a swarm of robots deployed on the floor of the tank. The gantry operates to controllably move a touchdown point of the cable, which is being fed into the tank by a cable engine. Each of the robots is equipped with a rake that can be used to push or pull downed sections of the cable on the floor of the tank. An electronic controller operates to control the speed of the cable engine and movements of the gantry and individual robots to coil the cable in the tank in spirally wound, vertically stacked layers. Different embodiments of the system may be used for cable coiling at the cable factory and on the deck of a cable-laying ship.

Abstract: A method for measuring a response from an optical fiber providing distributed back reflections using a system comprising an optical source comprising a laser, an optical receiver and a processing unit is disclosed. The method comprises establishing initial parameters of a distributed back-reflection processing. The method also comprises generating an interrogation signal and an optical local oscillator using the optical source, the interrogation signal being represented by an interrogation phasor and the optical local oscillator being represented by a local oscillator phasor; transmitting the interrogation signal into the optical fiber; and mixing the optical local oscillator with reflected light from the optical fiber and detecting a mixing product with the optical receiver to achieve a receiver output signal.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the optical ports thereof. In an example embodiment, the supervisory optical circuit provides one or more pathways therethrough for supervisory optical signals, each of these pathways having located therein a respective narrow band-pass optical filter. The supervisory optical circuit further provides one or more pathways therethrough configured to bypass the corresponding narrow band-pass optical filters in a manner that enables backscattered light of any wavelength to cross into the optical path that has therein the unidirectional optical amplifier directionally aligned with the propagation direction of the backscattered light.

Abstract: In certain embodiments, an assembly has intermediate pods magnetically, but not galvanically, coupled along an electrically conductive cable. Each pod has a magnetic core surrounding and inductively coupled to the cable and one or more coils inductively coupled to the magnetic core. The pod transmits, for example, outgoing current pulses on the cable by inducing electrical signals in the cable using a transmitter coil and the magnetic core. In addition, the pod repeats, for example, incoming current pulses on the cable by inducing electrical signals in the cable using the transmitter coil and the magnetic core, based on electrical signals induced in a receiver coil via the magnetic core by the incoming current pulses. Such an assembly can function as a data collection system for scientific research and/or as an early-warning system for events, such as earthquakes and tsunamis, without having to modify the cable itself.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the corresponding unidirectional optical paths. In an example embodiment, the supervisory optical circuit provides three pathways therethrough for supervisory optical signals, the first pathway being from the output of the first optical amplifier to the input of the second optical amplifier, the second pathway being between the input of the first optical amplifier and the input of the second optical amplifier, and the third pathway being from the output of the second optical amplifier to the input of the first optical amplifier. The pathways are arranged such that the remote monitoring equipment of the corresponding optical transport system can use optical time-domain reflectometry to determine and monitor, as a function of time, the individual gains of the first and second optical amplifiers.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the corresponding two optical paths through the repeater. In an example embodiment, the supervisory optical circuit is symmetrical in the sense that it enables the two optical input/output port pairs of the repeater to be interchangeable and functionally equivalent at least with respect to two supervisory wavelengths and some in-band and/or out-of-band wavelengths. This symmetry can advantageously be used, e.g., to improve the installation process directed at installing such optical repeaters in an undersea cable system. For example, a single directional orientation of the optical repeaters does not need to be maintained throughout the cable system, which can significantly reduce the risk and/or cost of installation errors.

Abstract: A landing station whose monitoring equipment employs a depolarized light source for generating the supervisory optical signals that are used to monitor certain performance characteristics of the corresponding submerged fiber-optic cable plant. In some embodiments, the depolarized light source operates to provide amplified spontaneous emission (ASE) within the bandwidths of the supervisory wavelength channels, with the supervisory optical signals being generated by modulating the provided ASE. In some other embodiments, the depolarized light source operates to generate a supervisory optical signal by modulating two carrier waves having (i) mutually orthogonal polarizations and (ii) different respective carrier wavelengths both of which are within the bandwidth of the corresponding supervisory wavelength channel.

Abstract: An optical transceiver capable of optimizing the performance of the corresponding optical channel by dynamically adjusting the optical power of the output signal in response to the FEC-performance data received from the corresponding remote transceiver. In an example embodiment, the FEC-performance data can be exchanged by the two optical transceivers using a dedicated field in the overhead of the transmitted data frames. The power-adjustment process is configured to be relatively slow to prevent the occurrence of transients on other optical channels and ensure stable operation of the corresponding WDM system as a whole, while different transceivers thereof are allowed to adjust their respective output powers in an autonomous way and independent of each other.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the corresponding two optical paths through the repeater. In an example embodiment, the supervisory optical circuit is symmetrical in the sense that it enables the two optical input/output port pairs of the repeater to be interchangeable and functionally equivalent at least with respect to two supervisory wavelengths and some in-band and/or out-of-band wavelengths. This symmetry can advantageously be used, e.g., to improve the installation process directed at installing such optical repeaters in an undersea cable system. For example, a single directional orientation of the optical repeaters does not need to be maintained throughout the cable system, which can significantly reduce the risk and/or cost of installation errors.

Abstract: A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the optical ports thereof. In an example embodiment, the supervisory optical circuit provides one or more pathways therethrough for supervisory optical signals, each of these pathways having located therein a respective narrow band-pass optical filter. The supervisory optical circuit further provides one or more pathways therethrough configured to bypass the corresponding narrow band-pass optical filters in a manner that enables backscattered light of any wavelength to cross into the optical path that has therein the unidirectional optical amplifier directionally aligned with the propagation direction of the backscattered light.

Abstract: A landing station whose monitoring equipment employs a depolarized light source for generating the supervisory optical signals that are used to monitor certain performance characteristics of the corresponding submerged fiber-optic cable plant. In some embodiments, the depolarized light source operates to provide amplified spontaneous emission (ASE) within the bandwidths of the supervisory wavelength channels, with the supervisory optical signals being generated by modulating the provided ASE. In some other embodiments, the depolarized light source operates to generate a supervisory optical signal by modulating two carrier waves having (i) mutually orthogonal polarizations and (ii) different respective carrier wavelengths both of which are within the bandwidth of the corresponding supervisory wavelength channel.

Abstract: An optical transceiver capable of optimizing the performance of the corresponding optical channel by dynamically adjusting the optical power of the output signal in response to the FEC-performance data received from the corresponding remote transceiver. In an example embodiment, the FEC-performance data can be exchanged by the two optical transceivers using a dedicated field in the overhead of the transmitted data frames. The power-adjustment process is configured to be relatively slow to prevent the occurrence of transients on other optical channels and ensure stable operation of the corresponding WDM system as a whole, while different transceivers thereof are allowed to adjust their respective output powers in an autonomous way and independent of each other.

Abstract: A system for transmitting signals in the form of soliton pulses over long distances using an optical conductor minimizes distortion of the transmitted soliton pulses using, in combination, a phase modulator to prevent temporal jitter of the soliton pulses and a set of filters of the type in which the frequency varies with the location of the filter or a set of saturable absorbent components to prevent deterioration of the signal to noise ratio of the pulses. Applications of the system include transoceanic optical communications.

Abstract: A terminal for a bidirectional synchronous digital hierarchy link with automatic protection switching conveying multiplexed data includes two send devices. Each send device includes a device for extracting from each of the two SDH multiplexes a signal indicating a far end remote failure. It further includes a device for receiving two SDH multiplexes and multiplexing them with service data specific to the link with automatic protection switching into a single multiplex to be sent over a first line. It inserts into this service data the two far end remote failure signals and two additional far end remote failure signals, these two additional signals being supplied by the other send device. The terminal further includes an automatic protection switch for transmitting to the first line one of the two multiplexes supplied by the respective send devices. Applications include underwater links.

Abstract: A system is disclosed for monitoring repeaters of an installation for transmission of signals via optical conductors in which each repeater includes an optical amplifier for amplifying the signals transmitted by the optical conductors. A remote monitoring signal is transmitted from a main or monitoring center to each repeater. The system includes, at the main center, a remote monitoring signal transmitter having a wide spectrum of optical wavelengths, preferably at least as wide as the wanted spectrum of wavelengths of the optical signals transmitted on the conductors. In this way the wanted signal is virtually undisturbed by the remote monitoring signal.

Abstract: In an optical communication system using polarization scrambling of the transmitted optical signal, the scrambling causes the polarization vector to rotate. The scrambler includes a modulator to modulate either the phase or the wavelength of the optical signal. A polarization dispersion device converts the phase modulation or wavelength modulation into polarization modulation. This polarization dispersion device consists of the optical communication fibers on the output side of the modulator.

Abstract: In an optical transmission method solitons are transmitted through a succession of fibers in which their intensity progressively decreases. To limit distortion of the solitons, this decrease in their intensity is accompanied by a decrease in the chromatic dispersion of the fibers. In accordance with the invention, the succession of fibers includes at least a first fiber featuring continuously longitudinally decreasing chromatic dispersion. Subsequent fibers feature respective longitudinally constant chromatic dispersions forming a longitudinally decreasing sequence. Applications include telecommunications.