Abstract: A method of operating a quantum information processing apparatus is provided. This apparatus includes a structure of coupled qubits, where N?3, wherein the structure further includes coupling elements. The coupling elements couple pairs of N qubits, wherein, at least, a portion of the qubits are connected by a respective one of the coupling elements, whereby the two qubits of each said pair are connected by a respective coupling element. A method comprises identifying a path of M qubits in the structure of coupled qubits, wherein the path extends from a first qubit to a last qubit of the N qubits. The identified path consists of M qubits and M?1 coupling elements alternating along said path, where 2<M?N. A single-cycle operation is performed, wherein all pairs of two successive qubits in the identified path are concomitantly subjected to exchange-type interactions of distinct strengths.

Abstract: In an optical network based on a dense wavelength division multiplexing system using a flexible frequency grid, it is difficult to improve the usage efficiency of an optical frequency band owing to the occurrence of fragmentation of the optical frequency band; therefore, an optical network controller according to an exemplary aspect of the present invention includes an optical frequency region setting means for dividing an optical frequency band used in an optical network based on a dense wavelength division multiplexing system using a flexible frequency grid, and setting a plurality of optical frequency regions; and an optical path setting means for setting optical paths having a common attribute in at least one of the plurality of optical frequency regions.

Abstract: Methods and apparatus for removing beat interference from the splitting and/or combining of signals. In one embodiment, an active splitter/combiner receives multiple input optical signals from downstream communication resources via a number of individual point-to-point links. Each input optical signal is converted to an electric signal (which, unlike the input optical signals, do not share a characteristic wavelength). The resulting electrical signals can be combined without introducing beat interference. Once combined, the resulting aggregate signal is converted back to an optical format for transmission via the optical network. Various other aspects of the present disclosure are directed to active splitting of optical signals.

Abstract: A system, method and device provide passive operation mode and noise management. The system, in one embodiment, includes power loss bypass and upstream noise management.

Abstract: A system, method and device provide passive operation mode and noise management. The system, in one embodiment, includes power loss bypass and upstream noise management.

Abstract: When an unsafe port with a loss of signal is detected, a transceiver may enable one laser in a group of lasers associated with the unsafe port and may disable the remaining lasers. Then, the transceiver may instruct a transmitter associated with the one laser to transmit an optical signal on the unsafe port using a reduced transmit power that is less than a threshold value associated with the Class 1 conditions and at a different time than enabled lasers in other groups of lasers. Alternatively, for a safe port on which valid communication is received, the transceiver may enable lasers in a group of lasers associated with the safe port. Then, the transceiver may instruct transmitters associated with the lasers in this group of lasers to transmit optical signals on the safe port using a normal transmit power for the lasers that is greater than the threshold value.

Abstract: A method of discovering addressing information of one or more upstream devices to respond to specific messages by a second device on behalf of the one or more upstream devices in a network includes acquiring the addressing information in an upstream direction from one or more downstream devices to the one or more upstream devices. The method further includes acquiring the addressing information in a downstream direction from the one or more upstream devices to the one or more downstream devices. The method further includes responding to specific messages using the acquired addressing information about the one or more upstream devices.

Abstract: A relay device includes a first transmitting and receiving unit connected to a PON line on the upper-level side and performing mutual conversion between optical and electrical signals; a second transmitting and receiving unit connected to a PON line on the lower-level side and performing mutual conversion between optical and electrical signals; a relay processing unit relaying a downstream frame received by the first unit to the second unit, and relays an upstream frame received by the second unit to the first unit; and a control unit. The control unit follows upstream multiple access control performed by a station side device, for transmission of the upstream frame to be transmitted by the first unit to the station side device, and independently performs upstream multiple access control for reception of the upstream frame received by the second unit from a home side device.

Abstract: A method is provided of creating an end-to-end entanglement (87) between qubits in first and second end nodes (81, 82) of a chain of optically-coupled nodes whose intermediate nodes (80) are quantum repeaters. Local entanglements (85) are created on an on-going basis between qubits in neighboring pairs in the chain through interaction of the qubits with light fields transmitted between the nodes. The quantum repeaters (80) are cyclically operated with their top-level operating cycles being synchronized. Once every top-level operating cycle, each repeater (80) initiates a merging of two entanglements involving respective repeater qubits that are at least expected to be entangled with qubits in nodes disposed in opposite directions along the chain from the repeater. A quantum repeater (80) adapted for implementing this method is also provided.

Abstract: A method for amplifying optical signals includes determining a source optical signal, generating a first resultant signal including a pump signal and the source optical signal, sending the first resultant signal through a non-linear element to generate a second resultant signal including the first resultant signal and an idler signal, and sending the second resultant signal through a non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal, the pump signal, and the idler signal. The method also includes filtering the third resultant signal to remove the pump signal and the idler signal and outputting the amplified source optical signal.

Abstract: All-optical phase-modulated data signal regenerator apparatus (10) comprising an optical input (12), an optical signal converter (16), an optical carrier signal source (18), optical signal forming apparatus (20) and an optical output (14). The input (12) is arranged to receive a phase-modulated optical data signal. The signal converter (16) is arranged to receive the data signal and to convert phase modulation of the data signal into a corresponding intensity modulation of an intermediate optical signal. The carrier signal source (18) provides an optical carrier signal.

Abstract: A method, an apparatus, and a system for transmitting information in a passive optical network are provided. The method mainly includes: obtaining OAM information that an RE device needs to report to an OLT device, performing modulation processing, according to the OAM information, on a downlink optical signal sent by the OLT device, and returning the downlink optical signal after the modulation processing to the OLT device; or, obtaining OAM information that an OLT device needs to deliver to an RE device, performing modulation processing, according to the OAM information, on a downlink optical signal sent by the OLT device to the RE device, and sending the downlink optical signal after the modulation processing to the RE device.

Abstract: A semiconductor optical amplifier includes an n-type semiconductor layer, a p-type semiconductor layer an active layer provided between the n-type semiconductor layer and the p-type semiconductor layer, the active layer transmitting an optical signal and a current-injection part that injects current into the active layer via the n-type semiconductor layer and the p-type semiconductor layer, the active layer including a first active layer that includes AlGaInAs, and a second active layer that includes GaInAsP, the second active layer provided closer to an output side than the first active layer, and the first active layer and the second active layer being butt-jointed.

Abstract: A light receiving device includes: a converter digitalizing an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal; a plurality of fixed distortion compensators compensating an output signal of the converter for waveform distortion with a fixed compensation amount that is different from each other; a plurality of phase shift detector circuits detecting a sampling phase shift from an output signal of the plurality of the fixed distortion compensators; a phase-adjusting-amount determiner determining a sampling phase adjusting amount with use of an output signal of the plurality of the phase shift detector circuits; and a phase adjusting circuit reducing a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.

Abstract: Provided is a quantum repeater network system that does not need any matter qubit. According to the quantum repeater network system for performing quantum communication between one transmitter/receiver and the other transmitter/receiver via transmission repeaters and reception repeaters, each of the transmission repeaters prepares quantum systems in an irreducibly entangled state, each of said quantum systems being associated with a reception repeater as a transmission destination, and transmits, to the associated reception repeater, each of the quantum systems in the irreducibly entangled state together with a quantum system entangled with the quantum system.

Abstract: A relay device includes: a housing including: a first surface; and a second surface which is different from the first surface; a light signal receiving element operable to receive a light signal from outside, the light signal receiving element provided at the first surface of the housing; a light emission element operable to emit light responsive to the light signal received by the light signal receiving element; and a longitudinally elongated light guide member provided at the second surface of the housing, the light guide member to which the light emitted from the light emission element is incident, the light guide member including an emission part which causes the incident light to be emitted to outside from a lateral surface of the light guide member, the lateral surface which extends along a longitudinal direction of the light guide member.

Abstract: A method for regenerating optical signal includes determining a source optical signal to be regenerated, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, creating a first conjugate optical signal and a second conjugate optical signal from the intermediate optical signal, and performing degenerate phase-sensitive amplification utilizing the first conjugate optical signal, the second conjugate optical signal and the source optical signal to yield an output optical signal. The source optical signal is modulated with a multilevel modulation format. Each conjugate optical signal has a phase that is a conjugate of a multiple of the phase of the source optical signal.

Abstract: A method and apparatus for suppressing pump-mode optical beat interference noise in a Raman amplified fiber link of an optical network, wherein a wavelength of a laser beam generated by a first pump laser and a wavelength of a laser beam generated by a second pump laser of a pair of polarization multiplexed pump lasers are detuned with respect to each other to suppress the optical beat interference, OBI, noise in the Raman amplified fiber link of said optical network.

Abstract: Optical regenerators and amplifiers are expensive to implement and maintain. A method or corresponding apparatus in an example embodiment of the present invention relates to an optical planning tool that plans an optical network configuration by determining a plurality of costs for maintaining signal strength in corresponding network configurations including (i) a configuration of regenerators, (ii) a configuration of pre-or post-amplifiers, and (iii) a configuration of pre- and post-amplifiers in candidate locations and regenerator modules. The candidate locations for placing pre-or post-amplifiers are determined based on loss in each span, expected traffic patterns, and proposed regeneration locations along paths of expected traffic. The regeneration modules are located in locations determined based on the candidate locations. The example embodiment selects a configuration from among the network configurations as a function of the plurality of costs, helping reduce the cost of network deployment.

Abstract: A technique for controlling power of a network node in an optical mesh network, comprising: determining a number of optical paths ingressing or expected to ingress the node, determining capacity or expected capacity of each of the paths; calculating for each of the paths a virtual input power Pvirtual, based on estimation of relative capacity of a specific path with respect to total capacity of all the paths; applying to the network node a power control mechanism, while utilizing a corresponding virtual input power Pvirtual as input power of any of the paths.

Abstract: Methods and apparatus for control of variable optical attenuators are described. A method for control of a variable optical attenuator located in an optical link comprising a plurality of optical attenuators. The method comprises determining that an initial calibration step of a variable optical attenuator has been completed, and transmitting a signal indicative of the variable optical attenuator having completed the initial calibration step for receipt by a downstream variable optical attenuator. A method of controlling a variable optical attenuator comprises receiving a signal indicative of an upstream variable optical attenuator having completed an initial calibration step, and initiating calibration of the variable optical attenuator in response to receipt of said signal.

Abstract: A method for reallocating a wavelength in an optical wavelength multiplexer transmission system is disclosed. The method includes switching a supply of a first channel electric signal from a first optical transmitter device to a second optical transmitter device, the first optical transmitter device converting the first channel electric signal into an optical signal of a first wavelength, and the second optical transmitter device converting the first channel electric signal into an optical signal of a second wavelength differing from the first wavelength, and transmitting the optical signal of the second wavelength output from the second optical transmitter device.

Abstract: Embodiments of the present invention provide a repeater, including a local unit and a remote unit. The local unit includes a base station interface unit, multiple local basic units and a controller. The remote unit includes multiple remote basic units. The controller is configured to generate, according to a down-tilt angle and/or azimuth angle of a downlink signal instructed by a control instruction, a downlink signal phase for each remote basic unit. The multiple local basic units each are configured to perform, according to the downlink signal phase generated by the controller for a corresponding remote basic unit, phase adjustment on the downlink signal sent by the base station interface unit. The multiple remote basic units each are configured to receive the downlink signal sent by a corresponding local basic unit and to send the downlink signal.

Abstract: An optical repeater in a mobile communication system includes a main hub unit (MHU) and a plurality of repeaters connected to a plurality of access points of the MHU, respectively. Each of the repeaters receives subcarrier information and a signal transmitted from a base station, as optical signals, through the MHU or a different repeater connected thereto, processes only a signal corresponding to a subcarrier allocated to a terminal which has accessed according to the subcarrier information, and transmits the processed signal to the terminal which has accessed. Also, each of the repeaters maps a signal of the terminal which has accessed to a subcarrier allocated to the terminal which has accessed, and transmits the same to the MHU or a different repeater connected thereto.

Abstract: An optical repeater formed in an optical passive component passively relays an incoming multiplexed optical signal. The repeater has an optical decoder decoding the multiplexed optical signal, and an optical encoder encoding an optical signal from a termination unit connected to the repeater. The repeater further includes a first optical path switch outputting an incoming multiplexed optical signal to the optical decoder and outputting the optical signal delivered from the optical decoder, a second optical path switch outputting the optical signal coming from the first optical path switch to the termination unit, and a third optical path switch outputting the optical signal coming from the second optical path switch to the encoder and outputting the optical signal delivered from the encoder.

Abstract: An iterative method is provided for progressively building an end-to-end entanglement between qubits in first and second end nodes (91, 92) of a chain of nodes whose intermediate nodes (90) are quantum repeaters. At each iteration, a current operative repeater (90) of the chain merges an entanglement existing between qubits in the first end node (91) and the operative repeater, with a local entanglement formed between qubits in the operative repeater and its neighbor node towards the second end node (92). For the first iteration, the operative repeater is the neighbor of the first end node (91); thereafter, for each new iteration the operative repeater shifts one node further along the chain toward the second end node (92). A quantum repeater adapted for implementing this method is also provided.

Abstract: A network component comprising at least one processor configured to implement a method comprising obtaining a wavelength availability information for a path, determining whether to implement a wavelength assignment based on the wavelength availability information, updating the wavelength availability information when the wavelength assignment is to be implemented, and forwarding the wavelength availability information. Also included is a method comprising obtaining a wavelength availability information, comparing a number of wavelengths in the wavelength availability information to a threshold, determining whether to implement wavelength conversion along a path when the number of available wavelengths is less than or about equal to the threshold, and resetting the wavelength availability information when wavelength conversion is to be implemented.

Abstract: An optical transmission system is provided. The optical transmission system includes a user side optical repeater device (ORD), a central office side ORD, and wavelength multiplexing and wavelength de-multiplexing functions (MUX/DEMUX). The user side optical repeater device (ORD) is to be connected with a user side optical network unit (ONU), transmits data in two ways, and is used for wavelength division multiplexing (WDM). The central office side ORD is to be connected with a central office side optical line terminal (OLT), transmits data in two ways, and is used for WDM. The wavelength multiplexing and a wavelength de-multiplexing functions (MUX/DEMUX), are used for relaying between the user side ORD and the central office side ORD.

Abstract: A system and method for sizing transponder pools in a dynamic wavelength division multiplexing optical network having selected nodes designated to have a shared transponder pool is presented.

Abstract: An apparatus comprising one or more optical amplifiers coupled to an optical link and configured to amplify a plurality of Wavelength Division Multiplexing (WDM) channels that are transmitted at a plurality of wavelengths on the optical link, and a processor coupled to the optical link and configured to add, delete, or both a plurality of WDM channels in the optical link based on an allowed power ratio indication for the WDM channels, wherein the allowed power ratio indication is calculated based on a plurality of gain change representations for the WDM channels at a plurality of power ratios and on a link budget requirement for the optical link.

Abstract: The present invention utilizes external synchronization to generate a completely standardized or functionally standardized optical transmission unit of level k (OTUk[V]) signal providing less jitter and wander build-up through a network of optical transport network (OTN) elements. This increases noise margins of transported signals and payloads. The present invention provides stratum-level synchronization utilizing a standards-based approach. In one embodiment of the present invention, rate adapters are included to provide m/n scaling of OTUk[V] signals to rates common in SONET and SDH synchronizers to provide line and loop distribution of timing through OTUk[V] signals. The present invention provides a choice of external synchronization sources including building integrated timing source (BITS), line, and loop timing sources. In another exemplary embodiment, the present invention provides multiple external references and automated timing protection switching for redundancy and reliability.

Abstract: A light receiving device includes: a converter digitalizing an analog signal with a given sampling clock frequency, the analog signal being obtained through a photoelectric conversion of a received optical signal; a plurality of fixed distortion compensators compensating an output signal of the converter for waveform distortion with a fixed compensation amount that is different from each other; a plurality of phase shift detector circuits detecting a sampling phase shift from an output signal of the plurality of the fixed distortion compensators; a phase-adjusting-amount determiner determining a sampling phase adjusting amount with use of an output signal of the plurality of the phase shift detector circuits; and a phase adjusting circuit reducing a phase difference between the sampling clock frequency and the received optical signal based on a determination result of the phase-adjusting-amount determiner.

Abstract: The invention relates to a bidirectional optical amplifier array (VA) which is preferably used in a passive optical network (PON) system, is disposed between a first line termination (OLT) and a second line termination (ONU), and is penetrated by an optical downstream signal (OSD) in one direction and an optical upstream signal (OSD) in the opposite direction. Said optical amplifier array is composed of a first part with two branching and combining units (D1 and D2), a unidirectional optical amplifier (E1), and a transponder (T) in which the optical downstream signals and upstream signals (OSU and OSD) are separately amplified. The two signals (OSU and OSD) that run in opposite directions are amplified in a bidirectional amplifier (E2) in a second part. A constant gain is maintained in the bidirectional optical amplifier (E2) by means of the continuous downstream signal (OSD) such that the amplifier can be operated in stable conditions for the upstream signal (OSU) regardless of occurring bursts.

Abstract: The present invention relates to an optical relay system for transmitting multi-band frequency signals with limited bands by using optical lines. According to the present invention, a plurality of band-limited signals are band-combined into one signal by using a combiner, and the signals are transmitted through multiple outputs by using a distributor, and thus a multi-stage filter is not necessary. In addition, the present invention is capable of effectively solving various problems such as damage to the original signals caused by the band combination of the multi-stage filter, and there is no need to precisely connect each of the band-limited signals to the determined ports of the combiner and the signals can be connected to random ports, thereby improving convenience of use.

Abstract: There is provides a wavelength conversion apparatus for converting a wavelength of input signal light and for outputting output signal light of the converted wavelength. The apparatus includes a first and a second nonlinear mediums. The first nonlinear medium receives a first input light and outputs a first output light having a wavelength which is longer than that of the first input light, the wavelength being dependent on optical power of the first input light. The second nonlinear medium receives a second input light and a light output by a light source and outputs a second output light having a wavelength dependent on the wavelengths of the second input light and the light. The first output light is input as the second input light to the second nonlinear medium or the second output light is input as the first input light to the first nonlinear medium.

Abstract: A multiple conductor optical cable may be coupled to an undersea device, such as a cable joint, branching unit, or repeater, with one or more isolated bypass conductive paths being provided across the undersea device. At least one conductor may be terminated within a housing of the undersea device and at least one conductor may be coupled to a conductive bridge member that provides the isolated bypass conductive path across the device. Multiple conductor optical cables may be coupled to undersea devices in optical networks using independent power paths, for example, to deliver power to different powered components at different voltage potentials.

Abstract: There is described a method for converting the wavelength of a pulsed optical signal. An input pulsed signal containing information and having an input wavelength is buffering by propagating the input pulsed signal in a closed-loop optical regenerative cavity. The propagation comprises converting the input pulsed signal at the input wavelength to a buffer pulsed signal at an adjustable wavelength and propagating the buffer pulsed signal within the cavity. The adjustable wavelength is set to a buffer wavelength different from the output wavelength and the buffer pulsed signal contains the information encoded in the input pulsed signal. The output wavelength is determined from the information encoded in the input pulsed signal. Upon determination of the output wavelength, the adjustable wavelength of the buffer pulsed signal is set to the output wavelength in order to; outputting the buffer pulsed signal at the output wavelength from the cavity.

Abstract: A repeater (1) includes a master unit (2) for communicating with a base station of a mobile network, a plurality of remote units (3) for communicating with mobile communications terminals, and a common optical waveguide (4) connecting the remote units (3) with the master unit (2) for transmitting the optical signals from each of the remote units (3) to the master unit (2). The remote units (3) include, as a transmitter for the optical signals, a laser (7) of a construction similar or somewhat identical to that of the other lasers (7). The lasers (7) have similar or somewhat identical nominal wavelengths (?N), and the individual lasers (7) are selected by adjusting their operating temperatures (TD1-TD4) in such a way that each laser transmits on a different transmission wavelength (?ü1-?ü4).

Abstract: A relay apparatus including: a first interface 11 that branches an optical signal that is input in a first direction from one side of the optical transmission line, and directs the optical signal to a first path and a second path, the first path being a processing path of an optical signal having a first transmission speed, the second path being a processing path of an optical signal having a second transmission speed that is different from the first transmission speed; a processing section 12 that executes processing on an optical signal propagating through each of the paths in accordance with a corresponding transmission speed; and a second interface 13 that binds the first path and the second path of the optical signal on which the processing is executed by the processing section, by means of wavelength multiplexing and directs to the other end of the optical transmission line.

Abstract: A waveform shaping apparatus includes a quantum dot optical amplifier in which an amplification factor of input signal beams saturates if the optical power of the signal beams is equal to or greater than a predetermined value; and a quantum dot saturable absorber in which an absorption factor of the input signal beams saturates if the optical power of the signal beams is under a predetermined value. The quantum dot optical amplifier and the quantum dot saturable absorber are connected in series with a transmission path of the signal beams, and shape the waveform of the signal beams. Voltages applied to the quantum dot optical amplifier and the quantum dot saturable absorber, respectively, are adjusted based on the optical power of the signal beams.

Abstract: An optical system for providing all-optical up-conversion of a baseband signal including an all-optical up-converter responsive to baseband signals to provide corresponding dual sideband signals about a suppressed optical carrier, said dual sideband signals each having the same polarization direction, being phase locked, having the same optical power and having a fixed frequency spacing; and an optical filter for filtering the carrier signals and providing wavelength division multiplexed signals without optical carriers.

Abstract: There are provided surge protection devices for undersea optical repeaters. An optical repeater drive circuit incorporating a diode chain design includes a diode array formed of a plurality of banks of two or more parallel forward-biased diodes, each diode in a given bank being in electrical contact with all the diodes in adjacent banks; and, optical repeater control circuitry connected in parallel with the diode array. A component for providing surge protection to an optical repeater incorporates a substrate formed of an insulating material and a first substantially planar conducting coil embedded within the substrate.

Abstract: A repeater is disclosed that transmits an optical signal using wave division multiplexing. The repeater includes a demultiplexing unit that separates plural channels contained in the optical signal, an adjusting unit that adjusts at least optical power of each of the channels according to a control signal, a multiplexing unit that outputs a multiple wavelength signal in which the channels are multiplexed, and a monitoring unit that determines a modulation scheme and a bit rate of the optical signal for each of the channels so as to generate the control signal.

Abstract: An optical repeater in a mobile communication system includes a main hub unit (MHU) and a plurality of repeaters connected to a plurality of access points of the MHU, respectively. Each of the repeaters receives subcarrier information and a signal transmitted from a base station, as optical signals, through the MHU or a different repeater connected thereto, processes only a signal corresponding to a subcarrier allocated to a terminal which has accessed according to the subcarrier information, and transmits the processed signal to the terminal which has accessed. Also, each of the repeaters maps a signal of the terminal which has accessed to a subcarrier allocated to the terminal which has accessed, and transmits the same to the MHU or a different repeater connected thereto.

Abstract: When a conventional optical receiver circuit is used, it is difficult to achieve noise reduction or provide a multichannel capability due to a considerable circuit area increase. Disclosed is an amplifier for optical communications that includes a CMOS inverter, which has a PMOS transistor and an NMOS transistor; an input terminal, which inputs a signal into the CMOS inverter; an output terminal, which outputs a signal from the CMOS inverter; a power supply, which is connected to the CMOS inverter; a first element and a second element, which are respectively connected to the CMOS inverter; and two types of power supply paths, which are in opposite phase to each other.

Abstract: An optical transmission system is provided. The optical transmission system includes a user side optical repeater device, a central office side optical repeater device, and wavelength multiplexing and wavelength de-multiplexing functions. The user side optical repeater device is to be connected with a user side optical network unit, transmits data in two ways, and is used for wavelength division multiplexing. The central office side optical repeater device is to be connected with a central office side optical line terminal, transmits data in two ways, and is used for wavelength division multiplexing. The wavelength multiplexing and wavelength de-multiplexing functions are used for relaying between the user side optical repeater device and the central office side optical repeater device.

Abstract: Systems and methods for a reconfigurable, long-range, underwater data-communication network are described. The network provides a low cost, low power, lightweight, and easy to deploy underwater communication system capable of being operated at long distances. The network may include a cabled ocean observatory, which may be deployed underwater and connected to a surface buoy. The cabled ocean observatory may be connected to one or more removable underwater sensors via fiber optic cables. The underwater sensors may be disposed at underwater locations at long distances from the cabled ocean observatory. Fiber optic extension modules may be permanently connected to each end of the fiber optic cables. Each fiber optic extension module may include an optical transceiver, a power supply, and an inductive element for removably coupling an underwater sensor or the cabled ocean observatory to the fiber optic cable.

Abstract: A digital radio frequency transport system that performs bi-directional simultaneous digital radio frequency distribution is provided. The transport system includes a digital host unit and at least two digital remote units coupled to the digital host unit. The bi-directional simultaneous digital radio frequency distribution is performed between the digital host unit and the at least two digital remote units.

Abstract: A repeater includes a variable optical attenuating unit that collectively attenuates WDM optical signal input, an optical-attenuation adjusting unit that adjusts attenuation in the variable optical attenuating unit, and an optical amplifying unit that collectively amplifies and outputs the WDM optical signal collectively attenuated, to a downstream side. An optical-attenuation adjusting unit includes an input level detector; an output level detector; an output-level transmitting unit that receives information of a signal level of WDM optical signal output by a repeater at an upstream side and transmits information of a signal level of the WDM optical signal detected by the output level detector to a repeater at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount thereof based on information of a signal level detected by the input level detector and a signal level received by the output-level transmitting unit.

Abstract: A transponder for performing bidirectional conversion between a client-side signal used for communication to a client device and a transmission path-side signal used for communication to a transmission path, the transponder comprising: a client-side interface for inputting/outputting the client-side signal; a transmission path-side interface for inputting/outputting the transmission path-side signal; a connection determining unit for determining which of the another client-side interface and the client device is coupled to the client-side interface; and a transmission signal generating unit for outputting, in a case where a state signal indicating a state on a transmission path side is input to the transmission path-side interface, a transmission signal indicating that the state signal has been input, from the client-side interface, wherein: the transmission signal generating unit changes a form of the transmission signal to be output from the client-side interface, based on a determination result obtained by