Abstract: A driver circuit for a semiconductor laser of the invention comprises: first bias current supply means for supplying, at least at a time of non-output of data, a first bias current to an LD; signal processing means for generating a pulse current control signal in which a burst data signal is delayed, and generating a second bias current control signal which rises more rapidly by a predetermined time than the rise of burst data included in the pulse current control signal; pulse current supply means for supplying to the LD a pulse current generated in accordance with the pulse current control signal; and second bias current supply means for supplying to the LD a second bias current generated in accordance with the second bias current control signal.

Abstract: A controlling apparatus and a controlling method of an optical switching device are capable of automatically correcting angle deviations of tilt-mirrors to thereby reduce an optical loss.

Abstract: A data relay apparatus that recovers a failure in a network that shares a part of a plurality of rings and avoids occurrence of a loop path by providing a block in each of the rings includes a failure-notification-packet transmitting unit that transmits, when a failure is detected in a shared portion of a ring, a failure notification packet to a predetermined redundancy-providing ring; and a block setting unit that sets a block that blocks a main signal by passing through a control packet at a port where the failure is detected.

Abstract: A light source supplies optical signal to an optical switch and a detector detects light receiving level. A control unit changes a deflection control amount for changing an angle of a tilt mirror, and outputs the deflection control amount to a driving unit. When an input and an output ports are same, optical offset of the tilt mirror is calculated based on optimal angle at which the light detector detects an optimal point of the light receiving level. Whenever the input and the output port are different, a structure parameter of the tilt mirror is calculated based on the optical offset and the optimal angle. The optical offset and the structure parameter are stored in a memory as a test result.

Abstract: A node device of an optical ring network is disclosed. With the node device, a counterclockwise auxiliary wavelength supplied from a third switch part is returned and supplied to a clockwise add/drop part when there is a fault in an optical transmission path on a left side, a clockwise auxiliary wavelength supplied from a second switch part is returned and supplied to a counterclockwise add/drop part when there is a fault in an optical transmission path on a right side, a clockwise active wavelength supplied from a clockwise add/drop part is returned and supplied to a first switch part when there is a fault in the optical transmission path on the right side, and a counterclockwise active wavelength supplied from the counterclockwise add/drop part is returned and supplied to a fourth switch part when there is a fault in the optical transmission path on the left side.

Abstract: A node device of an optical ring network is disclosed. With the node device, a counterclockwise auxiliary wavelength supplied from a third switch part is returned and supplied to a clockwise add/drop part when there is a fault in an optical transmission path on a left side, a clockwise auxiliary wavelength supplied from a second switch part is returned and supplied to a counterclockwise add/drop part when there is a fault in an optical transmission path on a right side, a clockwise active wavelength supplied from a clockwise add/drop part is returned and supplied to a first switch part when there is a fault in the optical transmission path on the right side, and a counterclockwise active wavelength supplied from the counterclockwise add/drop part is returned and supplied to a fourth switch part when there is a fault in the optical transmission path on the left side.

Abstract: An optical transmission circuit includes: a semiconductor laser; a drive circuit for supplying drive current to the semiconductor laser; a duty changing circuit for changing a duty value of an input data; a converting circuit for supplying a duty control signal to the duty changing circuit in order to adjust the duty value of the input data; and an adjusting circuit for supplying an optical power control signal to the converting circuit and the drive circuit. The adjusting circuit performs an initial setting of an optical power of the semiconductor laser, and the converting circuit performs the initial setting of the duty value so as to have a characteristic opposite to the optical power. According to the above structure, it is possible to realize the duty adjustment and the optical power adjustment by using only one adjusting circuit so that it is possible to achieve a simplified, miniatuarized, and low cost optical transmission circuit.

Abstract: The present invention aims at providing a control apparatus and a control method of an optical signal exchanger, capable of controlling an optical output level to be constant even when performing the switching of channels with different optical input levels. To this end, according to the control apparatus of the optical signal exchanger, in a three-dimensional type optical signal exchanger using a set of MEMS mirror arrays each having a plurality of tilt mirrors arranged on a plane, each tilt mirror having a reflecting surface an angle of which is controllable, power of an optical signal sequentially reflected by the respective MEMS mirror arrays and output from a specific position is detected by an optical power detection section, and the angle of the reflecting surface of the tilt mirror that has reflected the optical signal is feedback controlled, so that an absolute value of a difference between a previously set target value and the output light power becomes minimum.

Abstract: In a digital filter device which filters a plurality of signals by a single digital filter, an input data memory stores the input data strings generated by computing processors, and a digital filter reads the input data strings in a predetermined sequence to be filtered and generates output data strings. An output data memory stores the output data strings, and a data processor reads the output data strings in a predetermined sequence to be processed. Also, a switch table for associating an address of the input data memory in which the input data strings are stored with an address of the output data memory in which the output data strings are stored is provided, and based on this switch table, a switching controller provides timings of reading the input data strings out of the input data memory and of writing the input data strings as the output data strings into the output data memory through the digital filter.

Abstract: The present invention aims at providing an optical switch control method capable of controlling at a high speed angles of a plurality of tilt mirrors of an optical switch of three-dimensional structure, by a simplified circuit structure. To this end, for an optical switch including a plurality of mirror arrays each arranged with a plurality of tilt mirrors and in which input optical signals are sequentially reflected by the mirror arrays so as to output the optical signals from particular positions, the optical switch control method according to the present invention is constituted to divide the tilt mirrors on one mirror array into a plurality of fixed regions, to divide the tilt mirrors on the other mirror arrays into a plurality of virtual regions, in accordance with connecting states of optical paths, such that the tilt mirrors in each of the virtual regions and the tilt mirrors in each of the fixed regions are related to each other so as to make pairs.

Abstract: The present invention aims at providing an optical switch control method capable of controlling at a high speed angles of a plurality of tilt mirrors of an optical switch of three-dimensional structure, by a simplified circuit structure. To this end, for an optical switch including a plurality of mirror arrays each arranged with a plurality of tilt mirrors and in which input optical signals are sequentially reflected by the mirror arrays so as to output the optical signals from particular positions, the optical switch control method according to the present invention is constituted to divide the tilt mirrors on one mirror array into a plurality of fixed regions, to divide the tilt mirrors on the other mirror arrays into a plurality of virtual regions, in accordance with connecting states of optical paths, such that the tilt mirrors in each of the virtual regions and the tilt mirrors in each of the fixed regions are related to each other so as to make pairs.

Abstract: An object of the invention is to provide a control apparatus and a control method having a simple constitution, which can stably perform switching of optical path in an optical signal exchanger, while suppressing an influence on a control due to the mechanical resonance of tilt mirrors. To this end, the control apparatus of the optical signal exchanger is constituted such that in an optical signal exchanger of three-dimensional type using one set of MEMS mirror arrays, each having a plurality of tilt mirrors arranged on a plane, each tilt mirror having a reflecting surface an angle of which is controllable, when the angle of the MEMS mirror on the optical path is feedback controlled by detecting power of an optical signal output from a specific position, a resonance component removing section that removes a resonance frequency component included in a control signal is shared corresponding to a pair of driving electrodes arranged in a coaxial direction of the MEMS mirror.

Abstract: The present invention aims at providing a control apparatus and a control method of an optical signal exchanger, capable of controlling an optical output level to be constant even when performing the switching of channels with different optical input levels. To this end, according to the control apparatus of the optical signal exchanger, in a three-dimensional type optical signal exchanger using a set of MEMS mirror arrays each having a plurality of tilt mirrors arranged on a plane, each tilt mirror having a reflecting surface an angle of which is controllable, power of an optical signal sequentially reflected by the respective MEMS mirror arrays and output from a specific position is detected by an optical power detection section, and the angle of the reflecting surface of the tilt mirror that has reflected the optical signal is feedback controlled, so that an absolute value of a difference between a previously set target value and the output light power becomes minimum.

Abstract: In an optical subscriber network having a station, a plurality of subscriber units and an optical transmission line through which optical signals are sent and received by the station and plurality of subscriber units, (1) wavelengths &lgr;1-&lgr;n for delay time measurement are allocated respective ones of the subscriber units; (2) delay-measurement optical signals having these wavelengths are wavelength-multiplexed and transmitted, the number of these multiplexed optical signals being equivalent to the number of subscribers; (3) the wavelength-multiplexed delay-measurement optical signals are distributed to each of the subscriber units via a star coupler in the optical transmission line; (4) each subscriber unit selects, by wavelength selection, a delay-measurement optical signal having the wavelength that has been allocated to it, and loops back the selected optical signal; (5) the star coupler of the optical transmission line combines the delay-measurement optical signals returned from each of the subscrib

Abstract: The present invention aims at providing a controlling apparatus and a controlling method of an optical switching device capable of automatically correcting angle deviations of tilt-mirrors to thereby reduce an optical loss.

Abstract: The invention is aimed at providing an optical switch using tilt mirrors, in which easy mounting of the optical components is possible by simplifying the construction, and in which a short spatial propagation distance for the light beam is realized. To this end, the optical switch using tilt mirrors of the present invention comprises; a collimator array and a tilt mirror array each formed with an input section and an output section aligned and integrated, and a shift type turn-back mirror that shifts the optical path of the incident light in a predetermined direction and turns back and outputs this.

Abstract: A driver circuit for a semiconductor laser of the invention comprises: first bias current supply means for supplying, at least at a time of non-output of data, a first bias current to an LD; signal processing means for generating a pulse current control signal in which a burst data signal is delayed, and generating a second bias current control signal which rises more rapidly by a predetermined time than the rise of burst data included in the pulse current control signal; pulse current supply means for supplying to the LD a pulse current generated in accordance with the pulse current control signal; and second bias current supply means for supplying to the LD a second bias current generated in accordance with the second bias current control signal.

Abstract: The invention is aimed at providing an optical switch using tilt mirrors, in which easy mounting of the optical components is possible by simplifying the construction, and in which a short spatial propagation distance for the light beam is realized. To this end, the optical switch using tilt mirrors of the present invention comprises; a collimator array and a tilt mirror array each formed with an input section and an output section aligned and integrated, and a shift type turn-back mirror that shifts the optical path of the incident light in a predetermined direction and turns back and outputs this.

Abstract: An optical transmitting apparatus used in an optical communicating system in an optical communication network using a broad-band characteristic of fibers, which can transmit wavelength division multiplexed optical signals over the optical communication network, has an optical signal generating unit for generating optical signals for the respective plural opposite apparatus by using a combination of p (p; an integer not less than 2) wavelengths set in advance for each of the plural opposite apparatus, and a wavelength division multiplexing transmitting unit for wavelength division multiplexing the optical signals generated by the optical signal generating unit and transmitting the optical signals, thereby accommodating subscriber terminals larger in number than the number of times of wavelength division multiplexing while realizing privacy protection.

Abstract: The present invention relates to a fixed-length cell transmission system, a fixed-length cell transmitting unit and a fixed-length cell receiving unit. The fixed-length cell transmitting unit determines at least one optical transmitting section to be put to use, on the basis of band information of an inputted fixed-length cell to drive that optical transmitting section and sends the inputted fixed-length cell to that optical transmitting section. The fixed-length cell receiving unit is coupled through an optical transmission line to the fixed-length cell transmitting unit and is equipped with a plurality of optical receiving sections for converting a fixed-length cell of an optical signal into an electric signal and outputting the converted electric signal. In addition, the fixed-length cell receiving unit drives the optical receiving section corresponding to the optical transmitting section to be put to use in the fixed-length cell transmitting unit.