Abstract: An optical amplifier repeater system includes an optical fiber propagating a light beam in a plurality of propagation modes and an optical amplifier repeater amplifying the light beam propagated through the optical fiber. The optical amplifier repeater includes an optical demultiplexer demultiplexing the light beam in the plurality of propagation modes propagated through the optical fiber into a plurality of single-mode light beams, an optical amplifier amplifying, by simultaneous pumping, intensities of the plurality of single-mode light beams using a light beam generated by one pumping light source, an optical multiplexer multiplexing the plurality of single-mode light beams amplified by the optical amplifier into a light beam in the plurality of propagation modes, and an optical intensity adjusting unit adjusting the intensity of each of the plurality of single-mode light beams at least one of before or after the amplification by the optical amplifier.

Abstract: An optical amplification system includes: three or more nodes; a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of the connection between the nodes; an amplification light input unit configured to input amplification light to a core of the plurality of cores of the multi-core fiber; an amplification unit configured to amplify communication light transmitted through at least one core of the plurality of cores of the multi-core fiber using the amplification light, the amplification unit being provided in the nodes or between the nodes; and an amplification light coupling unit configured to couple the amplification light input by the amplification light input unit to the amplification unit.

Abstract: Provided is a mode equalization filter that reduces a light intensity difference between multiple modes of signal light propagating in a core of a few-mode fiber. The mode equalization filter according to the present invention includes: a collimator lens that collimates the signal light emitted from the few-mode fiber; a partial ND filter including a small dot having small transmittance with respect to the collimated signal light; and condensing lenses that condense the signal light transmitted through the partial ND filter on the few-mode fiber. The small dot having the small transmittance is arranged in a part of the partial ND filter, and the partial ND filter is arranged such that, when the collimated signal light is transmitted, a part of the collimated signal light overlaps with the small dot having the small transmittance.

Abstract: An optical transmission system includes a plurality of transmission paths that transmit a mode multiplexing signal, and one or more mode permutation units provided between the transmission paths. The mode permutation unit performs mode permutation to interchange modes to be used between at least some optical signals among respective optical signals of a plurality of types of modes that are multiplexed to the mode multiplexing signal input from the transmission path on an input side, and outputs the mode multiplexing signal subjected to the mode permutation to the transmission path on an output side.

Abstract: There is provided a multimode optical amplifier that provides gain to a plurality of propagation modes of signal light. The multimode optical amplifier includes a multiplexer that multiplexes the signal light and excitation light; an amplifying fiber which has a core that propagates a predetermined plurality of propagation modes of the signal light and a predetermined plurality of propagation modes of the excitation light, and which provides an individual gain value for each of the predetermined propagation modes of the signal light; a wavelength-flattening filter that maintains a constant gain value for a frequency for all predetermined propagation modes of the signal light; and a mode-flattening filter that maintains the gain value at a constant value for a predetermined propagation mode of the signal light for all predetermined propagation modes of the signal light.

Abstract: A signal receiving apparatus includes at least one signal separating apparatus that separates a specific signal from a plurality of received signals. Each of the at least one signal separating apparatus includes a spatial filtering unit that separates at least one equalized signal and a decision signal outputting unit that generates a first decision signal by deciding the equalized signal and outputs the generated first decision signal. The spatial filtering unit separates the at least one equalized signal by multiplying at least the plurality of received signals among the plurality of received signals and either the first decision signal output from the decision signal outputting unit or a second decision signal output from another signal separating apparatus by predetermined weighting coefficients.

Abstract: A casting solidification analysis method, which can analyze positions of shrinkage cavities more accurately than in the past, a casting method using the above method, and an electronic program are provided. A following casting solidification analysis method is provided. An amount of expansion/shrinkage for each solidification step length separated by inflection points in a cooling curve is determined, by setting a solid phase ratio at a completion of pouring to 0, setting a solid phase ratio at an end of solidification to 1.0, and determining the expansion/shrinkage amount for the each solidification step length by proportionally distributing the each solidification step length to the total solid phase ratio length.

Abstract: An optical node device includes one or more input-side wavelength selection switches, a plurality of output-side wavelength selection switches, and an amplification unit. The input-side wavelength selection switches include a plurality of output ports, separate input light in accordance with a wavelength, and output the separated light from the output port corresponding to an output destination of the separated light. The output-side wavelength selection switches include input ports each receiving the light output from each of the one or more input-side wavelength selection switches, multiplex the light received from the input ports, and output the light. The amplification unit amplifies the light output from each of the output ports of the input-side wavelength selection switches and outputs the amplified light to the output-side wavelength selection switch at the output destination corresponding to the output port.

Abstract: A signal receiving apparatus includes at least one signal separating apparatus that separates a specific signal from a plurality of received signals. Each of the at least one signal separating apparatus includes a spatial filtering unit that separates at least one equalized signal and a decision signal outputting unit that generates a first decision signal by deciding the equalized signal and outputs the generated first decision signal. The spatial filtering unit separates the at least one equalized signal by multiplying at least the plurality of received signals among the plurality of received signals and either the first decision signal output from the decision signal outputting unit or a second decision signal output from another signal separating apparatus by predetermined weighting coefficients.

Abstract: An optical modulator according to embodiments includes a first MZI and a second MZI each including a first optical coupler that splits CW light into two, a second optical coupler that couples the CW light split by the first optical coupler and outputs the CW light, and a bias electrode that adjusts a phase of the CW light split by the first optical coupler, a third optical coupler that couples outputs of the first MZI and the second MZI with at a predetermined ratio and outputs the light, and a bias adjustment circuit that adjusts an output voltage of a bias power supply applied to a bias electrode so that an optical path length difference between the CW light beams split by the first optical coupler is a predetermined times a carrier wavelength under a condition that an output of a differential output amplifier is a zero level, in accordance with an operating mode of the own apparatus.

Abstract: An optical node device includes: a multicore optical amplification unit that amplifies collectively light transmitted along a multicore fiber; a separation unit that inputs the amplified light in each core to each of a plurality of input-side single-core fibers; an optical cross-connect switch that attenuates the light input from each of the plurality of input-side single-core fibers through an optical attenuator, separates the light in accordance with a wavelength, and outputs the separated light to an output-side single-core fiber of a plurality of output-side single-core fibers related to a respective output destination; a plurality of single-core optical amplification units that amplify the light transmitted along the corresponding output-side single-core fibers; and an output unit that outputs the light transmitted along each of the plurality of output-side single-core fibers to a multicore fiber.

Abstract: A manufacturing method of a mounting structure includes: a step of preparing a mounting member including a first circuit member and a plurality of second circuit members placed on the first circuit member; a disposing step of disposing a thermosetting sheet and a thermoplastic sheet on the mounting member, with the thermosetting sheet interposed between the thermoplastic sheet and the first circuit member; a first sealing step of pressing a stack of the thermosetting sheet and the thermoplastic sheet against the first circuit member, and heating the stack, to seal the second circuit members and to cure the thermosetting sheet into a cured layer; and a removal step of removing the thermoplastic sheet from the cured layer. At least one of the second circuit members is a hollow member having a space from the first circuit member, and in the first sealing step, the second circuit members are sealed so as to maintain the space.

Abstract: An optical node device includes: a multicore optical amplification unit that amplifies collectively light transmitted along a multicore fiber; a separation unit that inputs the amplified light in each core to each of a plurality of input-side single-core fibers; an optical cross-connect switch that attenuates the light input from each of the plurality of input-side single-core fibers through an optical attenuator, separates the light in accordance with a wavelength, and outputs the separated light to an output-side single-core fiber of a plurality of output-side single-core fibers related to a respective output destination; a plurality of single-core optical amplification units that amplify the light transmitted along the corresponding output-side single-core fibers; and an output unit that outputs the light transmitted along each of the plurality of output-side single-core fibers to a multicore fiber.

Abstract: An optical transmission system includes a plurality of transmission paths that transmit a mode multiplexing signal, and one or more mode permutation units provided between the transmission paths. The mode permutation unit performs mode permutation to interchange modes to be used between at least some optical signals among respective optical signals of a plurality of types of modes that are multiplexed to the mode multiplexing signal input from the transmission path on an input side, and outputs the mode multiplexing signal subjected to the mode permutation to the transmission path on an output side.

Abstract: A manufacturing method of a mounting structure, the method including a step of preparing a mounting member including a first circuit member and a plurality of second circuit members placed on the first circuit member; a disposing step of disposing a thermosetting sheet and a thermoplastic sheet on the mounting member, with the thermosetting sheet interposed between the thermoplastic sheet and the first circuit member; a first sealing step of pressing a stack of the thermosetting sheet and the thermoplastic sheet against the first circuit member, and heating the stack, to seal the second circuit members and to cure the thermosetting sheet into a first cured layer; a removal step of removing the thermoplastic sheet from the first cured layer; and a coating film formation step of forming a coating film on the first cured layer, after the removal step.

Abstract: An optically amplified repeater system includes optical transmission paths, a multi-channel optical amplifier, one or more Raman amplification pumping light sources, and a wavelength multiplexer. The multi-channel optical amplifier includes K simultaneous pumping light sources, N optical amplification media, and one or more optical couplers, and simultaneously amplifies, with the K simultaneous pumping light sources, light intensities of optical signals that pass through the N optical amplification media and propagate through the optical transmission paths. Light intensities of the wavelength band of the optical signals is Raman amplified by the Raman amplification pumping light. A light intensity of the Raman amplification pumping light output from the one or more Raman amplification pumping light sources is determined in accordance with characteristic differences between the optical signals passing through the optical transmission paths.

Abstract: A transmission quality estimation system includes, three or more nodes and a transmission quality estimation device configured to estimate, transmission quality. A multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes. A node of the nodes includes a core connection unit configured to drop, add or relay light transmitted from, to or to each of to the plurality of cores of the multi-core fiber. The transmission quality estimation device includes an estimation unit configured to estimate transmission quality between the nodes on the basis of a transmission quality measurement light dropped by the core connection unit.

Abstract: A transmission quality estimation system includes, three or more nodes and a transmission quality estimation device configured to estimate, transmission quality. A multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes. A node of the nodes includes a core connection unit configured to drop, add or relay light transmitted from, to or to each of to the plurality of cores of the multi-core fiber. The transmission quality estimation device includes an estimation unit configured to estimate transmission quality between the nodes on the basis of a transmission quality measurement light dropped by the core connection unit.

Abstract: A communication system which includes: three or more nodes; a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of a connection between the nodes; a detection signal output unit configured to output a fault detection signal transmitted by the core provided in the multi-core fiber configured to connect together the nodes; and a fault detection unit configured to determine whether a fault has occurred between the nodes on the basis of a detection result of the fault detection signal.

Abstract: An optical transmission system includes an optical transmission apparatus and an optical reception apparatus. The optical transmission apparatus includes a conversion unit that converts multiple binary data sequences into data in a predetermined signal format; a coding unit that generates multiple pieces of coded data by performing predetermined coding on each of the multiple pieces of converted data; an optical signal generation unit that generates multiple optical signals by converting the multiple pieces of coded data into optical signals; and a mode multiplexer that converts the multiple optical signals into different modes, generates a mode-division multiplexed optical signal by mode-division multiplexing the optical signals, and transmits the generated mode-division multiplexed optical signal to the optical reception apparatus.