Abstract: A communication system and a timing control method are proposed that optimize timing in a sender and thereby enable information to be stably transmitted at the right timing. Under instructions from a timing controller in a receiver, the timing of driving a phase modulator in a sender is shifted by one step after another, and the then amount of clock shift and result of interference are monitored at the receiver and stored in a memory. The optimum timing is determined based on the stored data. Thus, a clock for driving the phase modulator in the sender can be set at the right timing. This is equivalent to compensating for group velocity dispersion due to wavelength dispersion that occurs when an optical signal channel and a clock signal channel are transmitted by wavelength division multiplexing transmission.

Abstract: A communication system capable of employing polarization-dependent phase modulators with a reversing configuration that preserves security against disturbance of a polarization state at a transmission path but without using Faraday mirrors and a communication method using the same are provided. A quantum cryptography system of the present invention includes a first station 1, a transmission path 2, and a second station 3. The first station 1 has means for emitting time-divided optical pulses into the transmission path 2 and measuring a phase difference between the optical pulses returning from the transmission path 2. The transmission path 2 is a medium of light.

Abstract: A method and apparatus for measuring the optical power of very weak light arriving at a receiver, by using a photon detector, are provided. A photon detector detects the presence or absence of the arrival of a photon in accordance with bias application timing. For a train of optical pulses coming in at an arbitrary timing in respective time slots, the bias application timing is sequentially shifted within the range of a time slot. Each time a shift is made, the number of photons detected is counted by a photon counter. Based on this number of photons, the optical power of the train of the optical pulses is measured.

Abstract: The first present invention provides an optical switch including the following elements. At least a plurality of optical transmission lines are provided for transmissions of optical signals. Each of the at least plurality of optical transmission lines have at least an impurity doped fiber. At least an excitation light source is provided for emitting an excitation light.

Abstract: A sender transmits to a receiver an optical signal that is phase-modulated in accordance with source data and a basis stored in a memory. The receiver phase-modulates the received optical signal in accordance with a basis, obtains detection data through interference, and stores the detection data in a memory. An inter-device address difference (GD) and an intra-device address difference (DI) are provisionally set. The detection data are checked against the source data while sequentially changing the values of GD and DI within a predetermined adjustment range. Based on the result of this checking, GD and DI are determined.

Abstract: For an error rate QBER, threshold values are preset, including a threshold value Qbit for frame synchronization processing, a threshold value Qphase for phase correction processing, and a threshold value QEve for eavesdropping detection. Upon the distribution of a quantum key from a sender to a receiver, when the measurement value of QBER is deteriorated more than Qbit, frame synchronization processing is performed. When the measurement value of QBER is deteriorated more than Qphase, phase correction processing and frame synchronization processing are performed. When QBER does not become better than QEve even after these recovery-processing steps are repeated N times, it is determined that there is a possibility of eavesdropping, and the processing is stopped.

Abstract: A modular plug has a modular housing, a first array of terminals retracted from a second array of terminals disposed at the front end of the modular housing. The unraveled wires are received in respective slots arranged in two rows in the housing. The slots have a shield function for preventing, the cross-talk between the unraveled wires.

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: Provided is a measuring device 1 for measuring the size of an object comprising a body 2, and a spindle 3 which is screwed into the body 2 and axially advances and retracts by screwing with respect to the body 2, the measurement being based on the axial displacement of the spindle 3 effected by the revolution of the spindle, wherein the spindle is screwed into the body 2 via a multiple-start thread 31. Therefore, it is possible to displace the spindle 3 at a high speed, which improves the operability of the measuring device.

Abstract: An address translator capable of reducing system loads in address translation and an overhead in switching between operating systems. A plurality of address translation buffers classifies and stores virtual addresses and real addresses based on a plurality of operating systems which is run by a processor. For example, the address translation buffers store the virtual addresses and the real addresses in correspondence with the operating systems. According to a running operating system, an address translation controller accesses a corresponding address translation buffer to translate virtual addresses to real addresses.

Abstract: An optical packet exchange apparatus and an optical switch in which search for a connection pattern between an input unit devoid of a packet to be transmitted and an output unit devoid of a packet to be received is reduced to enable fast switch control even in cases wherein the number of channels of the exchange apparatus is increased or network speed is higher. A plurality of input units, a plurality of output units and an optical switch are provided. Each input unit includes an input buffer unit, a parallel/serial conversion unit, an electrical/optical conversion unit, and a dummy packet insertion unit for sending a dummy packet if there is no packet to be transmitted. Each output unit includes an exchange counterpart contention resolution unit for controlling the exchange counterpart, an optical/electrical conversion unit, a serial/parallel conversion unit, and a packet eliminating unit. The exchange counterpart contention resolution unit controls the packet eliminating unit to eliminate a dummy packet.

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: An ultrasonic shower cleaning apparatus is disclosed which is capable of efficiently cleaning both surfaces of an article and configured to have a reduced size enabling an installation space thereof to be decreased. A pair of ultrasonic shower cleaning mechanisms each include a nozzle, a disc-shaped ultrasonic transducer arranged so as to face a backward end of the nozzle and an inlet port for a cleaning liquid formed opposite to a side surface of the nozzle. The ultrasonic shower cleaning mechanisms are integrally incorporated in one casing in such a manner that axes of the nozzles cross each other at a predetermined angle. The casing is provided with one inlet branch port connected to the inlet ports of the ultrasonic shower cleaning mechanisms. The casing may have a groove formed therein in which an edge of the article arranged between the two nozzles can be inserted.

Abstract: A modular plug has a modular housing, a first array of terminals retracted from a second array of terminals disposed at the front end of the modular housing. The unraveled wires are received in respective slots arranged in two rows in the housing. The slots have a shield function for preventing, the cross-talk between the unraveled wires.

Abstract: A compact and simple linear actuator includes a spindle to a main body so as to be capable of moving in an axial direction, displacement detection device, a motor, and a transmission mechanism. The displacement detection device detects a movement displacement amount of the spindle. The motor is disposed adjacent a proximal end one of the spindle and on the same axis as the spindle. The transmission mechanism transmits turning force of the motor to the spindle. The transmission mechanism includes a first rotary member fitted to the proximal end of the spindle and integrally rotating with the spindle, a second rotary member fitted to a rotor of the motor, and connection rods for transmitting rotation of the second rotary member to the first rotary member. The connection rods have axes that are parallel to an axis of the spindle while being displaced from the spindle axis.

Abstract: A packet switching network which allows the duration of guard time of each packet to be reduced to a minimum and the transmission efficiency of the network to be increased is disclosed. The sending nodes send the packet switch packets each having a guard time added thereto. The receiving nodes receive the packets from the packet switch. Each of the receiving nodes includes a switch timing detector for detecting switch timing of the packet switch based on a serial signal received from the packet switch, and a timing holder for holding the switch timing.

Abstract: An optical receiving circuit 1 is composed of a preamplifier circuit 2, an output differential amplifier 3 and a mean value holding circuit 4. The optical receiving circuit 1 is connected to a photodetector 5 for receiving an input optical signal and outputting current. For the preamplifier circuit 2, a transimpedance type circuit may also be used. The preamplifier circuit 2 comprises a feedback resistor 21 and a resistor for detecting output voltage 22, the transimpedance gain is 55 dB &OHgr; and 3 dB bandwidth when the photodetector 5 the capacity of which is 0.2 pF is connected to its output is 8 GHz. The output differential amplifier 3 discriminates and regenerates data by regulating reference voltage Vref between the high level and the low level of the amplitude of an input signal. The mean value holding circuit 4 includes a sample-hold circuit 41 and capacity 42 for holding the mean value of voltage output from the preamplifier circuit 2.