Abstract: An optical repeating system includes an optical transmitter and a plurality of optical amplifying repeaters. The optical transmitter specifies a part or all of the optical amplifying repeaters, and transmits a supervisory command to the specified optical amplifying repeaters as a first sub-signal via an uplink or downlink optical transmission line. The supervisory command is a command to supervise internal circuits of the optical amplifying repeaters. Receiving the supervisory command addressed thereto via the uplink or downlink optical transmission line, the optical amplifying repeaters each transmit a supervisory signal indicating a supervisory result corresponding to the supervisory command to optical receivers via the uplink and downlink optical transmission lines as a second sub-signal. The optical system can reduce the time take to acquire the supervisory information about the plurality of the optical amplifying repeaters.

Abstract: An optical repeating system includes an optical transmitter and an optical amplifying repeater. The optical transmitter transmits a supervisory command and a control command to the optical amplifying repeater as a first sub-signal. The supervisory command is a command to supervise internal circuits of the optical amplifying repeater, and the control command is a command to control the optical amplifying repeater. The optical amplifying repeater includes multiple sub-modules each for amplifying and repeating main signals on multiple sets of optical transmission lines. When receiving the supervisory command via the optical transmission line, each sub-module transmits a supervisory signal indicating the supervisory result associated with the supervisory command to an optical receiver as a second sub-signal.

Abstract: To control a gain profile in an optical fiber line to become a desirable form, a C-OTDR measuring apparatus (36) outputs a probe pulse light having a wavelength ?m for an optical fiber line (14). A power level on the input or output side of a variable gain equalizer (22) can be measured according to a C-OTDR waveform of a return light of the probe pulse light entered through a C-OTDR path (20c) and an optical fiber line (16). By sweeping the measurement wavelength ?m, the gain file is measured. The equalizing characteristics of the variable gain equalizer (22) are remotely controlled so that the gain profile becomes a desirable form according to the measured result.

Abstract: In an optical repeating system including an optical transmitter and optical amplifying repeaters, the optical transmitter specifies one optical amplifying repeater, and transmits to the optical amplifying repeater a supervisory command to supervise internal circuits of the optical amplifying repeater and a control command to control amplification factors of optical amplifiers of the optical amplifying repeater as a first sub-signal. Receiving the supervisory command via an optical transmission line, the optical amplifying repeater transmits a supervisory signal indicating a supervisory result corresponding to the supervisory command to optical receivers via optical transmission lines as a second sub-signal. Receiving the control command via the optical transmission line, the optical amplifying repeater is controlled to change amplification factors of the optical amplifiers in response to the control command.

Abstract: A supervisory system and supervisory method of an optical amplifier repeater are proposed that can implement operation supervision taking account of the characteristics of individual supervisory targets of the optical amplifier repeater, thereby achieving higher reliability.

Abstract: To control a gain profile in an optical fiber line to become a desirable form, a C-OTDR measuring apparatus (36) outputs a probe pulse light having a wavelength &lgr;m for an optical fiber line (14). A power level on the input or output side of a variable gain equalizer (22) can be measured according to a C-OTDR waveform of a return light of the probe pulse light entered through a C-OTDR path (20c) and an optical fiber line (16). By sweeping the measurement wavelength &lgr;m, the gain file is measured. The equalizing characteristics of the variable gain equalizer (22) are remotely controlled so that the gain profile becomes a desirable form according to the measured result.

Abstract: A technique for measuring optical characteristics includes providing a variable wavelength light source a fixed wavelength light source optical modulators for modulating the variable wavelength light and the fixed wavelength light, a fiber coupler for entering composite light generated by composing the variable wavelength light with the fixed wavelength light into a device under test, a circulator for extracting a variable wavelength light component from light transmitted through a fiber pair, and an optical filter for extracting a variable wavelength light component from the transmitted light, and measuring a phase difference of the variable wavelength light component with the fixed wavelength light component as a reference.

Abstract: A measuring system of transmission characteristics comprises a reference signal light generator for generating reference signal light of a reference wavelength optically intensity-modulated at a reference frequency, a measuring signal light generator for generating measuring signal light of a measuring wavelength optically intensity-modulated at a measuring frequency synchronizing with the reference frequency, a multiplexer for multiplexing the reference signal light and measuring signal light respectively generated by the reference signal light generator and measuring signal light generator and outputting them onto a to-be-measured optical line, a photodetector for converting the lights propagated on the to-be-measured line into electric signals, a reference frequency extractor for extracting the component of the reference frequency from the output of the photodetector, and a phase detector for detecting a phase of a frequency component corresponding to the measuring frequency contained in the output of the

Abstract: An optical repeating system includes an optical transmitter and an optical amplifying repeater. The optical transmitter transmits a supervisory command and a control command to the optical amplifying repeater as a first sub-signal. The supervisory command is a command to supervise internal circuits of the optical amplifying repeater, and the control command is a command to control the optical amplifying repeater. The optical amplifying repeater includes multiple sub-modules each for amplifying and repeating main signals on multiple sets of optical transmission lines. When receiving the supervisory command via the optical transmission line, each sub-module transmits a supervisory signal indicating the supervisory result associated with the supervisory command to an optical receiver as a second sub-signal.

Abstract: An optical repeating system includes an optical transmitter and a plurality of optical amplifying repeaters. The optical transmitter specifies one of the optical amplifying repeaters, and transmits a supervisory command and a control command to the specified optical amplifying repeater as a first sub-signal. The supervisory command is a command to supervise internal circuits of the optical amplifying repeater, and the control command is a command to control amplification factors of optical amplifiers of the optical amplifying repeater. Receiving the supervisory command via the uplink or downlink optical transmission line, the optical amplifying repeater transmit a supervisory signal indicating a supervisory result corresponding to the supervisory command to optical receivers via the uplink and downlink optical transmission lines as a second sub-signal.

Abstract: An optical repeating system includes an optical transmitter and a plurality of optical amplifying repeaters. The optical transmitter specifies a part or all of the optical amplifying repeaters, and transmits a supervisory command to the specified optical amplifying repeaters as a first sub-signal via an uplink or downlink optical transmission line. The supervisory command is a command to supervise internal circuits of the optical amplifying repeaters. Receiving the supervisory command addressed thereto via the uplink or downlink optical transmission line, the optical amplifying repeaters each transmit a supervisory signal indicating a supervisory result corresponding to the supervisory command to optical receivers via the uplink and downlink optical transmission lines as a second sub-signal. The optical system can reduce the time take to acquire the supervisory information about the plurality of the optical amplifying repeaters.

Abstract: To provide an apparatus for measuring chromatic dispersion when modulating frequency of a variable wavelength light source is different from modulating frequency of a fixed wavelength light source for reference.

Abstract: In an optical transmission, system, a trunk cable having two pairs of optical fibers is provided between first and second trunk stations to use one of the two pairs of the optical fibers for communication between the first and second trunk stations and the other for communication with first and second branch stations. Two branching units of first and second, and third and forth, are respectively provided for the first and second branch stations, and connected to each of the associated first and second branch stations, by first and second or third and forth branching cables. The first branch station connects to the first branching unit via the first branching cable having two pairs of optical fibers, and connects to the second branching unit via the second branching cable having two pairs of optical fibers.

Abstract: It is intended to provide an apparatus for measuring wave dispersion characteristic and the like only with one fiber pair.

Abstract: To provide an apparatus for measuring chromatic dispersion when modulating frequency of a variable wavelength light source is different from modulating frequency of a fixed wavelength light source for reference.

Abstract: A supervisory system and supervisory method of an optical amplifier repeater are proposed that can implement operation supervision taking account of the characteristics of individual supervisory targets of the optical amplifier repeater, thereby achieving higher reliability.

Abstract: A gain equalizer comprising an optical element having first and second input ports and an output port wherein the first transmission wavelength characteristics between the first input port and the output port and the second transmission wavelength characteristics between the second input port and the output port vary inversely each other relative to wavelengths, first and second input optical fibers to connect to the first and second input ports respectively, an output optical fiber to connect to the output port, and a housing to store the optical element.

Abstract: In an optical transmission system, an optical transmission line has up and down systems and loops back a supervisory light between the up and down systems. Trunk stations are provided at both ends of the optical transmission line and one or more optically branching units are provided in the optical transmission line for add/dropping a specific wavelength respectively. A branch station is connected to each of one or more the branching units. A bypass line for bypassing the supervisory light is provided in each of the one or more optically branching units.

Abstract: A feed line connecting circuit for selectively connecting first, second and third feed line connecting terminals under a predetermined current feeding condition comprises a first current detector connected between one of the first and second feed line connecting terminals and a central node for detecting a current over a predetermined value; a first switch connected between the one of the first and second feed line connecting terminals and the central node for connecting said one of the first and second feed line connecting terminals to the central node under an unpowered condition; a selective switch controlled by the first current detector, the selective switch having first and second contacts and a common contact connected to the third feed line connecting terminal, the common contact being connected to the first selective contact when the first current detector does not detect a current over the predetermined value, and to the second selective contact when the first current detector detects a current over

Abstract: A demultiplexer device is used in a wavelength-division multiplexed optical fiber communication line to achieve efficient dispersion compensation and loss compensation as well as a reduction of active devices such as optical amplifiers. The demultiplexer device has a series of couplers disposed in multi-stages from the input of the demultiplexer. Each coupler has two branches with one branch of each coupler connected to a separate optical filter and the other branches are series connected to a subsequent stage of the couplers through equalizing fibers, except for the final stage which has its second branch connected to an optical filter for the shortest wavelength transmitted. The equalizing fibers are thus serially connected between couplers and act to perform a cumulative dispersion compensation. The quantity of the equalizing fibers can thus be reduced as a whole, and as a result the attenuation amount also decreases, so that the number of optical amplifiers can be reduced.