Abstract: An organosilicon compound which is obtained by subjecting a compound (A), a compound (B) and a compound (C) to hydrosilylation reaction: (A) silicone and/or silsesquioxane that has two or more Si—H groups per one molecule and has a molecular weight of 100 to 500,000; (B) silicone and/or silsesquioxane that has two or more alkenyl groups per one molecule and has a molecular weight of 100 to 500,000; and (C) a compound that has one or more epoxy or oxetanyl group and an alkenyl group having 2 to 18 carbon atoms per one molecule.

Abstract: A clock signal of a master clock of a sender is transmitted to a receiver through a classical channel and is returned from the receiver. The clock signal is transmitted with strong light from a sender-side quantum unit to a receiver-side quantum unit through a quantum channel. A sender-side synchronization section establishes phase synchronization between the clock signal returned from the receiver and the clock signal detected by the sender-side quantum unit, and generates a calibration clock signal. At the receiver as well, a receiver-side synchronization section establishes phase synchronization between the clock signal detected from the classical channel and the clock signal detected by the receiver-side quantum unit, and generates a calibration clock signal.

Abstract: In a quantum cryptographic transmitter (11), a phase modulator (1103, 1104) and an LN intensity modulator (1105) apply optical phase modulation and light intensity modulation to an optical signal based on desired data to generate a desired optical signal to be transmitted to a quantum cryptographic receiver (13). Based on the number of photons detected from the desired optical signal, a bias control circuit (1108) controls an operating point in light intensity modulation of the LN intensity modulator (1105).

Abstract: The present invention provides a single fiber bidirectional optical transmission system capable of realizing the extension of a single fiber bidirectional long distance at a moderate price. An optical signal outputted from a second optical transmitter is incident on an optical amplifying portion passing through an optical circulator, a single fiber bidirectional transmission path, an optical circulator and an optical Blue/Red filter. The optical signal outputted from a first optical transmitter is incident on the optical amplifying portion passing through a dispersion compensator and the optical Blue/Red filter.

Abstract: A method and system for allowing communication devices to synchronously manage shared information are provided. A sender sends single-photon pulses modulated with original random numbers to a receiver and also sends frame pulses by using ordinary optical pulses. Bit comparison and basis reconciliation are performed by the frame which is defined by the frame pulses, whereby sifted keys, which are aggregated as a file, are generated by the sender and the receiver individually. The sifted keys are subjected to error correction, privacy amplification, and file sharing processing by the file, whereby common cryptographic keys are synchronously stored in the sender and the receiver individually. The generated cryptographic keys are managed as encryption keys and decryption keys separately. A newly generated key is preferentially placed in the encryption keys or decryption keys that have a smaller stored amount.

Abstract: A cryptographic key management method and device are provided by which cryptographic keys of multiple nodes can be managed easily and stably. A system includes at least one first node and a plurality of second nodes connected to the first node, and the first node individually generates and consumes a cryptographic key with each of the second nodes connected to the first node itself. A cryptographic key management device in such a system has a monitor that monitors the stored key amounts of cryptographic keys of the individual second nodes, stored at the first node, and a key management control section that performs key generation control on the first node, based on the stored key amounts.

Abstract: A transmitter-receiver having a means for automatically determining the status of transmission medium such as optical fiber, and a means for automatically setting and resetting the transmission rate and/or output power according to the status of the transmission medium, a transmission loss and gain measurement method, and a transmitting-receiving system. A transmitter-receiver comprises at least: an output power controller for controlling the output power of a transmitter; an input power measuring section for measuring the strength of input signals; and an information processor for deriving the loss or gain of a path to change the output power of the transmitter and/or the rate of data transmission according to the derived loss or gain of the path.

Abstract: A sender sends original random-number data to a receiver through a quantum channel. The receiver generates a raw key from information received through the quantum channel and notifies the received information to the sender. The sender performs received-bit comparison and basis reconciliation based on the received information and provisionally shares a sifted key with the receiver. The receiver sends part of its version of the sifted key to the sender, by which an error rate is calculated. The calculated error rate is compared with a predetermined threshold value for bit position synchronization determination. When the calculated error rate is larger, the sender notifies the receiver that bit position synchronization is not established. The receiver reassigns bit numbers to the sifted key, and received-bit comparison and basis reconciliation are performed again. This procedure is repeated until the calculated error rate becomes smaller than the threshold value.

Abstract: An optical network system is provided which has a signal protection function and is able to be constructed of communication nodes manufactured at low costs. An optical signal transceiver has at least one optical signal transmitting device and at least one optical signal receiving device to transmit and receive an optical signal between nodes facing each other. A switching device, when no failure has occurred in the optical signal transmitting communication line and optical signal receiving communication line, transmits an optical signal from the optical signal transmitting device to an optical signal transmitting communication line and an optical signal having been received from the optical signal receiving communication line to an optical signal receiving device.

Abstract: In a system where a quantum channel and a classical channel are multiplexed on a single optical transmission line and information is transmitted from a transmitter to a receiver through the quantum channel, the classical channel is inhibited from affecting the quantum channel. To this end, the transmission characteristics of a transmitter-side wavelength multiplexer/demultiplexer for the classical channel, the transmission characteristics of a receiver-side wavelength multiplexer/demultiplexer for the quantum channel, and the optical power of a light source for the classical channel are designed so that crosstalk light due to spontaneous emission light and crosstalk light due to nonlinear optical effects can be suppressed, and the classical channel does not affect the quantum channel.

Abstract: A method for managing shared random numbers in a secret communication network including at least one center node and a plurality of remote nodes connected to the center node, includes: sharing random number sequences between the center node and respective ones of the plurality of remote nodes; when performing random numbers sharing between a first remote node storing a first random number sequence shared with the center node and a second remote node storing a second random number sequence shared with the center node, distributing a part of the second random number sequence from the center node to the first remote node; and sharing the part of the second random number sequence between the first remote node and the second remote node.

Abstract: A photon detection circuit in which photon detection is performed by applying gate pulses to a light-receiving element at predetermined periods, includes: a gate-period waveform averaging section that generates averaged waveform data by averaging sampled waveform data output from the light-receiving element in the individual predetermined periods; a phase shifting section that shifts at least one of the phases of the averaged waveform data and sampled waveform data so that a phase difference between the averaged waveform data and sampled waveform date disappears; and a discrimination section that discriminates a photon detection based on the phase-adjusted sampled waveform data relative to the phase-adjusted averaged waveform data.

Abstract: A transmitter-receiver having a means for automatically determining the status of transmission medium such as optical fiber, and a means for automatically setting and resetting the transmission rate and/or output power according to the status of the transmission medium, a transmission loss and gain measurement method, and a transmitting-receiving system. A transmitter-receiver comprises at least: an output power controller for controlling the output power of a transmitter; an input power measuring section for measuring the strength of input signals; and an information processor for deriving the loss or gain of a path to change the output power of the transmitter and/or the rate of data transmission according to the derived loss or gain of the path.

Abstract: In a photo detecting circuit using an avalanche photodiode (APD), a pulse noise mask signal indicating the timing of occurrence of a pulse noise is generated by XORing a reverse-bias-pulse application timing signal and its delayed signal. Pulse noises are eliminated by ANDing an output signal of the APD and the pulse noise mask signal. Alternatively, a pulse noise is estimated by taking the average for the output current signal a given number of times. Pulse noises are eliminated by subtracting the estimated pulse noise from the APD output signal.

Abstract: A thermosetting resin composition containing a silsesquioxane derivative represented by the formula (1), cyclohexane-1,3,4-tricarboxylic 3,4-anhydride, and another acid anhydride, a cured material obtained by thermally curing the composition: The meanings of the symbols in the formula (1) are shown in the description.

Abstract: An optical transmitter which modulates the phases and intensities of double pulses and then transmits them, includes a branching section which branches each of the input double pulses to first and second paths, a first optical modulator placed in the first path, second and third optical modulators placed in series in the second path, and a combining section which combines the double pulses having traveled through the first path with the double pulses having traveled through the second path to output double pulses. A control section controls such that each of the first and second optical modulators performs any one of relative intensity modulation and relative phase modulation on the double pulses passing through, and the third optical modulator performs relative phase modulation on the double pulses passing through.

Abstract: A method and system for allowing communication devices to synchronously manage shared information are provided. A sender sends single-photon pulses modulated with original random numbers to a receiver and also sends frame pulses by using ordinary optical pulses. Bit comparison and basis reconciliation are performed by the frame which is defined by the frame pulses, whereby sifted keys, which are aggregated as a file, are generated by the sender and the receiver individually. The sifted keys are subjected to error correction, privacy amplification, and file sharing processing by the file, whereby common cryptographic keys are synchronously stored in the sender and the receiver individually. The generated cryptographic keys are managed as encryption keys and decryption keys separately. A newly generated key is preferentially placed in the encryption keys or decryption keys that have a smaller stored amount.

Abstract: A random number quality control circuit capable of fast control of the level of random number quality is present. When a “0” output section and a “1” output section generate random numbers by individually receiving a random number signal, a random number quality monitor monitors an unbalance between the numbers of “0”s and “1”s. If a deviation from a desired ratio is found, a drive controller controls the reception characteristics of the “0” output section and “1” output section individually so that the deviation will be compensated for. The amount of information intercepted between a sender and a receiver can be reduced by maintaining the mark ratio of shared random numbers at 50%.

Abstract: A secret communications system realizes point-to-multipoint or multipoint-to-multipoint connections of both quantum channels and classical channels. Multiple remote nodes are individually connected to a center node through optical fiber, and random-number strings K1 to KN are individually generated and shared between the respective remote nodes and the center node. Encrypted communication is performed between each remote node and the center node by using the corresponding one of the shared random-number strings K1 to KN as a cryptographic key. The center node is provided with a switch section for quantum channels and a switch section for classical channels. Switching control on each of these switch sections is performed independently of the other by a controller.

Abstract: A wavelength division-multiplexing system is provided that uses wavelength grids in conformity with the ITU-T Recommendation G.692 and that is realizable at lower costs. In the system, the wavelengths of signal light beams transmitted from plural optical transmitters are respectively spaced apart in such a manner that multiplexed wavelengths are set at regular intervals within the band range of the optical amplifier 5. The wavelength range of each laser beam covers at least two grids including neighboring grids. The wavelength demultiplexer 3 on the receiving side has the passband passing the wavelengths in a laser wavelength range corresponding to each channel.