摘要:
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.
摘要:
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. As a CR time constant based upon the capacity 42 and the resistor for detection 22 is 1 ns., the mean value level of a received signal can be detected in approximately one byte of the data of 10 Gb/s. The sample-hold circuit 41 samples the detected mean value level according to a sampling pulse from an external device and holds it. The output of the sample-hold circuit 41 is used for the reference voltage of the differential amplifier 3.
摘要:
Disclosed is an optical network which has: wavelength tunable optical transmitters of number MN, where N is an integer of two or more, each of which outputs an optical signal with arbitrary one of M wavelengths &lgr;1, &lgr;2, . . . , &lgr;M, where M is an integer of two or more, that are different from one another; a MN×N optical switch whose input ports are connected to the respective wavelength tunable optical transmitters of number MN, and which allows optical signals input to different input ports to be output form its same output port; 1×M optical wavelength demultiplexers of number N which output demultiplexing optical signal with wavelengths &lgr;1, &lgr;2, . . . , &lgr;M input from output ports of the MN×N optical switch into each wavelength; and optical receivers of number MN which receive optical signals input from the 1×M optical wavelength demultiplexers of number N.
摘要:
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.
摘要:
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.
摘要:
A bit synchronization circuit operates at high speed range as high as Gb/s or higher and can establish synchronization within 10 bits with rejecting jitter to permit accurate bit synchronization. The bit synchronization circuit thus generates a plurality of clocks having mutually different phases in synchronism with an input reference clock. A phase relationship between a plurality of clocks and an input data to be decided is discriminated by a phase comparator circuit. The clock having optimal phase relationship, namely clock having level transition timing having at a substantially center portion of mutually adjacent level transition timing of the input data, is determined by a phase determination circuit. An decision circuit and selector are provided for deciding input data at the level transition timing of the determined clock.
摘要:
The present invention provides means by which a switch controller that manages lines directly notifies receivers of ineffectiveness of received data upon line disconnection instead of any transmitter indirectly notifying receivers; and according to the invention, an optical transmitter is provided within the optical switching unit, and a switch controller controls the optical transmitter within the optical switching unit and an optical switch having at its input ports one or more dummy ports capable of multicast-transmission. According to this control, upon line disconnection, receivers are connected to the optical transmitter within the optical switching unit that transmits control code in real time, thereby preventing receivers from receiving ineffective data and obviating superfluous signal lines and communication processes between the switch controller and transmitters.
摘要:
Parallel digital data are transmitted along with a specific synchronization pattern added thereto. Each synchronization pattern adder adds the synchronization pattern at an equal timing for each channel. Parallel data after the synchronization pattern addition, are converted in parallel-to-serial converters into serial data which are in turn converted in an optical transmitter into optical signal. On the receiving side, the optical signal is converted in an optical receiver into an electric signal, from which the parallel data are restored in serial-to-parallel converters to be inputted to synchronization pattern detectors. The synchronization pattern detectors compare their shift register data and synchronization pattern and hold their synchronization pattern detection signal to be "1" for one time slot if the number of non-accord bits is within one. In the next time slot, a controller recognizes synchronization pattern detection when and only when all the synchronization pattern detection signals are "1". In this way, reliable synchronization pattern detection can be made regardless of the occurrence of any transmission error in the synchronization pattern.
摘要:
An optical filter having a transmission wavelength to be tuned dependent on light incident angle is rotatively provided in a collimated light path. The optical filter is rotated by the displacement of a piezoelectric actuator by a structure in which the displacement is converted to the rotation of the optical filter. The converting structure comprises a displacement magnifying mechanism for magnifying the displacement to provide the magnified displacement and a motion converting mechanism for converting the magnified displacement to the rotation of the optical filter.
摘要:
To optimize the number of optical gate switches required by an optical switching apparatus which comprises an optical space switch and wavelength selectors, the following process as a preliminary process of introducing optical signals into the optical space switch, is carried out. In detail, the preliminary process is optically converting the optical signals in relation to the number of input ports of the optical space switch, by optically processing the optical signals. As the results, the number of processed optical signals responding to the input ports and the processed number of wavelengths of each processed optical signal is equal to each other, and thereby, the optimization is achieved.