Abstract: An apparatus and a method for transmission of optical signals. The apparatus includes a bidirectional amplification device communicatively coupled between a first communication terminal and a second communication terminal. The first and second communication terminals are communicatively coupled using an optical communication link. The bidirectional amplification device is configured to transmit and amplify one or more optical sensing signals transmitted in either direction between the first communication terminal and the second communication terminal. The optical sensing signals indicate a status of one or more portions of the optical communication link.

Abstract: A distributed acoustic sensing system. The DAS system may include a distributed acoustic sensing (DAS) station, comprising: a DAS transmitter, arranged to launch an outbound DAS signal through an optical fiber, over at least one span; a DAS receiver, arranged to receive a backscatter Rayleigh signal, based upon the DAS signal; and at least one component, coupled to the DAS transmitter, the DAS receiver, or both, and arranged to increase a sensitivity for sensing of the DAS system.

Abstract: A receiver system may include a separating component to receive a reflected signal, comprising a frequency chirp-modulated signal, distributed over a plurality of wavelengths, and to separate the reflected signal according to wavelength into a plurality of optical signals; a coherent mixer array comprising a plurality of coherent mixers to mix the plurality of optical signals with a given local oscillator signal; a plurality of photodetectors to receive and convert, after the mixing, the plurality of optical signals into a plurality of electrical signals, respectively; a plurality of ADCs, configured to process the plurality of electrical signals concurrently, and output the plurality of electrical signals as a plurality of digital signals; and a DSP block, configured to receive the plurality of digital signals concurrently and to process the plurality of digital signals to convert the plurality of digital signals into phase data associated with the plurality of wavelengths, respectively.

Abstract: A multi-span distributed acoustic sensing system may include a first and second DAS transmitter, to transmit a first and second optical sensing signal respectively, each comprising a plurality of wavelengths; an optical cable, arranged over a plurality of spans to conduct the first optical sensing signal and second optical sensing signal; a plurality of repeaters, wherein a given repeater comprises a pair of loopbacks, wherein a first loopback and a second loopback are arranged to conduct a respective first and a second Rayleigh backscattered signal, to the second path and to the first path, respectively; a first receiver and a second receiver, to receive and to process the first and second Rayleigh backscattered signals respectively, wherein a time delay is applied to a first and second electrical signal derived from the first and second Rayleigh backscattered signals, respectively, according to a wavelength of the first and second Rayleigh backscattered signals.

Abstract: A multi-span distributed acoustic sensing (DAS) system may include: a DAS transmitter, operative to transmit an optical sensing signal over an outbound path, where the optical sensing signal comprises a plurality of wavelengths. The multi-span DAS system may further include an optical cable, arranged over a plurality of spans to conduct the sensing optical signal along the outbound path, a given span of the plurality of spans extending for a distance of 10 kilometers or more, and a plurality of loopbacks, distributed over the plurality of spans, and arranged to conduct a Rayleigh backscattered signal to a return path, where the Rayleigh backscattered signal is derived from the optical signal. The multi-span DAS system may further include a receiver, to receive and to process the Rayleigh backscattered signal, wherein a time delay is applied to an electrical signal derived from the Rayleigh backscattered signal according to a wavelength of the Rayleigh backscattered signal.

Abstract: A receiver system includes a separating component to separate a reflected signal according to wavelength into a plurality of optical signals; a coherent mixer array to generate a plurality of output signals at the plurality of wavelengths; a photodetector array to convert the plurality of output signals into a plurality of electrical signals, respectively; an analog to digital converter (ADC) assembly comprising a first ADC to output a first electrical signal as a digital signal that is associated with a given wavelength of the plurality of wavelengths; a clock to set a sampling instance for the first ADC that is separated from a sampling instance of a second ADC by a delay increment; and a DSP block, configured to process the digital signal, wherein the digital signal, associated with the given wavelength, is rearranged to indicate a location associated with a disturbance that generates a component of the reflected signal.

Abstract: An optical communication system and a method. The system includes a distributed acoustic sensing (DAS) interrogation unit. The DAS interrogation unit is configured to generate one or more optical signals for determining a status of one or more portions of an optical communication path, modulate one or more optical signals using one or more measurement pulses and generate one or more modulated optical signals, and transmit one or more modulated optical signals to the one or more portions of the optical communication path. The status of one or more portions of the optical communication path is determined based on one or more reflected signals reflected by one or more portions of the optical communication path in response to one or more modulated optical signals.

Abstract: An undersea fiber optic cable routing architecture including a branching unit coupled to three trunk cables capable of switching individual fibers in each fiber pair within a cable to either of the other two cables. The branching unit comprises a plurality of optical switches and a controller for receiving remote command signals and configuring the optical switches in accordance with the remote command signals.

Abstract: Provided is a cable and joint inspection system, process and computer readable medium enabling cable and joint inspection functions. The system includes an x-ray cabinet containing an x-ray camera and positioning equipment. The x-ray camera is positionable to obtain an x-ray image of a portion of a cable or a cable joint. The x-ray images are evaluated to determine whether a bounded area is within the x-ray image. The processor may measure the size of the bounded area in the x-ray image based on a number of pixels forming the bounded area. In response to the size of the bounded area being greater than an inclusion or void allowance threshold, the processor may flag the bounded area as an inclusion or void and flag pixel locations in the x-ray image. The flagged pixel locations correspond to a physical location within the portions of the cable or the cable joint.

Abstract: A system for distributed acoustic sensing comprising. The system may include a distributed acoustic sensing (DAS) station to launch a DAS signal into a DAS fiber; and an enhanced sensing array, the enhanced sensing array comprising at least one sensing component. The at least one sensing component may include a DAS fiber coil, forming a portion of the DAS fiber, and a low elastic modulus outer shell, surrounding the DAS fiber coil.

Abstract: A multicore optical fiber assembly is provided. The multicore optical fiber assembly may include an optical fiber, having a fiber diameter, a plurality of active cores, arranged within the optical fiber, and extending along a length of the optical fiber, and an energy blocker disposed within the optical fiber, and extending along the length of the optical fiber. As such, the energy blocker may be disposed between a first active core of the plurality of active cores, and a second active core of the plurality of active cores, where the energy blocker is arranged to block energy transfer from the first active core to the second active core.

Abstract: Techniques for improving gain equalization in C- and L-band (“C+L”) erbium-doped fiber amplifier (EDFAs) are provided. For example, the C- and L-band amplification sections of a C+L EDFA may be separated and configured in a parallel arrangement or a serial arrangement. For both the parallel and serial arrangements, the C- and L-band amplification sections may share a common gain flattening filter (GFF) or each amplification section may include and employ a separate GFF. Moreover, in some examples, an “interstage” L-band GFF may be located before or upstream of the L-band amplification section such that the L-band optical signal is gain-equalized or flattened prior to the L-band amplification section amplifying the L-band.

Abstract: An optical isolator for a fiber optic system. The optical isolator may include a polarization processing assembly, comprising a first polarization processing element and a second polarization processing element, a non-reciprocal optical element, disposed between the first polarization processing element and the second polarization processing element, and a reciprocal optical element assembly. The reciprocal optical element assembly may include a first reciprocal element, disposed between the non-reciprocal optical element and the first polarization processing element; a second reciprocal element, disposed between the non-reciprocal optical element and the second polarization processing element; and a patterning element to selectively direct light through the optical isolator according to a polarization of the light.

Abstract: A system may include a first DAS station, comprising a first plurality of interrogator units to launch a first plurality of DAS signals in a first direction, wherein a first interrogator unit is configured to launch a first DAS signal at a first interrogation rate and first wavelength, wherein a second interrogator unit is configured to launch a second DAS signal at a second wavelength and second interrogation rate, less than the first interrogation rate. The system may include a loopback array, comprising a plurality of loopbacks, arranged over a plurality of spans, wherein a first set of proximate loopbacks nearest to the first DAS station are configured to route back the first DAS signal to the first DAS station, and wherein a first set of intermediate loopbacks, located further from the first DAS station, are configured to route back the second DAS signal to the first DAS station.

Abstract: An optical communication system and method. The system includes a plurality of cable landing stations configured to be communicatively coupled using one or more optical communication cables in a peer-to-peer network for routing of one or more optical signals using one or more network elements. Each cable landing station includes a management device configured to determine one or more optical communication paths for routing optical signals, and a command/response optical device communicatively coupled to the management device for routing optical signals in accordance with the optical communication path. In response to receiving a request for routing at least one optical signal, the management device of each cable landing station is configured to determine at least one optical communication path for routing the optical signal in accordance with a topology map of the peer-to-peer network of the plurality of cable landing stations.

Abstract: A method and a system for transmission of optical signals. The system includes one or more first switching optical devices configured to switch transmission of one or more optical signals from one or more first fiber cores to one or more second fiber cores. It includes one or more second switching optical devices configured to pass-through transmission of one or more optical signals from one or more first fiber cores to one or more third fiber cores.

Abstract: Disclosed are a system and a method for configuring an optical transmission system. A process may include arranging a first ruggedized repeater on or in a first object or structure. A second ruggedized repeater may be arranged on or in a second object or structure different from the first object or structure. A third ruggedized repeater may be arranged on or in a third object or structure different from the first and second objects or structures, wherein: (i) a first distance between the first ruggedized repeater and the second ruggedized repeater and (ii) a second distance between the second ruggedized repeater and the third ruggedized repeater are equal or nearly equal and based on signal loss.

Abstract: A system and a method for monitoring an optical transmission path in an optical transmission system. The optical transmission system includes a sensing and interrogation unit and a plurality of sensing units positioned on the optical transmission path. An optical signal is transmitted to the plurality of sensing units for determining a status of one or more portions of an optical communication path. A plurality of reflected signals responsive to the optical signal are received. The plurality of reflected signals are transformed in at least one of: the frequency domain and the time domain. The status of one or more portions is determined using the transformed plurality of reflected signals.

Abstract: Techniques for improving gain equalization in C- and L-band (“C+L”) erbium-doped fiber amplifier (EDFAs) are provided. For example, the C- and L-band amplification sections of a C+L EDFA may be separated and configured in a parallel arrangement or a serial arrangement. For both the parallel and serial arrangements, the C- and L-band amplification sections may share a common gain flattening filter (GFF) or each amplification section may include and employ a separate GFF. Moreover, in some examples, an “interstage” L-band GFF may be located before or upstream of the L-band amplification section such that the L-band optical signal is gain-equalized or flattened prior to the L-band amplification section amplifying the L-band.

Abstract: A sensing system may include a distributed acoustic sensing (DAS) station to launch a DAS signal as an outbound DAS signal, as well as a plurality of DAS loopback assemblies, arranged along a plurality of spans. The plurality of DAS loopback assemblies may be arranged to separately process the outbound DAS signal, and return to the DAS station, the outbound DAS signal, as a return DAS signal that comprises a backscattered Rayleigh signal. As such, a given DAS loopback assembly of the plurality of DAS loopback assemblies may include an Erbium-Doped Fiber Amplifier (EDFA) that is arranged to compensate the loss from Rayleigh scattering of the DAS signal, and a filter device having an optical filtering function that is arranged to selectively send back just a sensing wavelength of the DAS signal.