JPH0621888A - Optical branching device with test supervisoring use port - Google Patents

Abstract

PURPOSE:To attain test and supervisor a practical star optical fiber independently of the number of branches by providing a wavelength independent coupling device to each radiation side signal port of the optical branching device. CONSTITUTION:At least two ports of a wavelength independent coupler 6 having, in general, four ports are allocated for signal ports and other at least one port 21 is allocated to a test supervisoring port. Then only a test supervisoring light wavelength allocated to each of the test supervisoring light from an optical pulse test device 12 is made incident in the port 21 of the wavelength independent coupling device 6 and a back scattering light generated in the star optical fiber 4 connecting to the coupling device 6 is emitted from the port 21 and received by the optical pulse test device 12. Thus, the back scattering light from all the star optical fibers 4 is not received but the light from the star optical fiber 4 connecting to each wavelength independent coupling device 5 is separately received and tested and supervisored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical branching device used in the field of optical communication, and more particularly to 1: N using an optical fiber.
The present invention relates to a test monitoring technique for an optical distribution line of (N> 1).

[0002]

2. Description of the Related Art FIG. 6 is a schematic configuration diagram for explaining the configuration of a conventional 1: N optical distribution type line. In FIG.
Reference numeral 1 is a signal light transmitting unit, 2 is a signal light receiving unit, 3 is a bus unit optical fiber, 4 is a star unit optical fiber, and 5 is a 1: N optical distribution unit. In this configuration, the signal light (wavelength λs) from the signal light transmitter 1 is transmitted through the bus optical fiber 3 and then
The light is distributed by the optical distribution unit 5 of the pair N and propagates to the signal light reception unit 2 via the N star optical fibers 4. Such a 1: N optical distribution line has a line configuration suitable for a video distribution service such as CATV, and has been widely studied.

By the way, (1) when a failure occurs in the 1-to-N optical distribution type line, a test for grasping the occurrence location and the degree of the failure, and (2) normal 1-to-N optical distribution type Described below is the problem when the line is monitored by the optical pulse test from the vicinity of the signal light transmitter 1 which is a conventional technique.

FIG. 7 is a schematic view for explaining a technique for performing an optical pulse test from the vicinity of the conventional signal light transmitting section 1, 11 is an optical coupler, and 12 is an optical pulse tester.

In FIG. 7, the test monitoring light (wavelength λt) from the optical pulse tester 12 is incident on the bus section optical fiber 3 by the optical coupler 11. The backscattered light from the bus section optical fiber 3 and the star section optical fiber 4 is reflected by the optical coupler 11.
The light is then received by the optical pulse tester 12. In this case, the backscattered light of the star part optical fiber 4 is received by the optical pulse tester 12 as a total of N lines and displayed as a backscattered waveform.

In such a conventional test monitoring system,
Consider a case where one of the N star part optical fibers 4 has a failure that causes an α (dB) loss. At this time,
When the failure point is searched for by the optical pulse tester 12, the distance between the failure point and the optical pulse tester 12 can be determined, but the failed star part optical fiber 4
Cannot specify any of the N lines.

Moreover, although the distance between the optical pulse tester 12 and the failure point can be determined, this is because the optical distribution type line is a distributed optical fiber such as a 1: 2 or 1: 4 optical distribution type line. When the number of distributions is large, for example, when the number of distributions is large, such as a 1-to-16 optical distribution type line, the optical pulse tester 12 can be used before and after the occurrence of a failure even with a disconnection (α = ∞).
The level difference β (dB) on the backscattering waveform observed at 1 appears only 0.28 (dB). The level difference of the backscattering waveform to this extent may be about the same as the waveform spread due to the noise of the optical pulse tester 12, and it becomes difficult to determine the distance between the optical pulse tester 12 and the failure point.

Therefore, each output side signal port has a dielectric band multilayer filter and has at least two pass wavelength bands, and a branching coupler with a filter (H. Yanagawa et al., “1 × N tree-splitter with a
commonfilter for branch identification, ”OFC '92,
pp263, 1992) has been proposed for a 1-to-N optical distribution unit, and its configuration is shown in FIG.

In FIG. 8, reference numeral 8 is a dielectric band multilayer filter. When this method is used, it is necessary for the filter 8 to transmit the signal light and the test monitoring light having a different wavelength for each star portion optical fiber 4 or for each small number of fibers. However, such a filter is extremely difficult to realize in terms of manufacturing and loss characteristics.

As described above, conventionally, even if one of the N star portion optical fibers 4 is broken, there is no effective means for monitoring the test.

[0011]

As described above, when the conventional technique is directly applied to the 1: N optical distribution type line, all the backscattered light of the star optical fiber 4 is transmitted to the optical pulse tester 12. Since it is displayed, there is a problem that the star optical fibers 4 cannot be effectively tested and monitored due to the dependence of the step difference β on the backscattering waveform observed by the optical pulse tester 12 before and after the failure occurrence on the distribution number N. It was Also, 1
Even when the branch coupler with a filter having the dielectric band multilayer film filter 8 is used for the light distribution unit 5 of the pair N, there is a problem that it is extremely difficult to realize the filter 8.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a 1 to N light distribution section 5.
Equipped with a wavelength-independent coupler at each output side signal port of
By using 2 ports of the coupler as signal ports, at least 1 other port for incidence / emission for test monitoring, and assigning a unique test monitoring wavelength to each test monitoring port It is an object of the present invention to provide a practical test monitoring technology for the star part optical fiber 4 that does not depend on the distribution number N, by performing test monitoring on the fibers 4 individually or on a small number basis.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0014]

In order to achieve the above object, the means (1) of the present invention is to divide the signal light incident from the incident side signal port into N (N> 1) and output side signal. In a 1-to-N optical branching device that emits light to a dedicated port, each outgoing-side signal port of the optical branching device comprises a wavelength-independent coupler, two ports of the coupler being a signal port and at least another one port. Is assigned to the test monitoring port.

According to a second aspect of the present invention, in the optical branching device with a test / monitoring port according to the above-mentioned means (1), a test / monitoring wavelength having a wavelength different from that of the signal light is individually combined with each emission side signal port. A wavelength multiplexing means for demultiplexing is provided at the test monitoring port.

[0016]

According to the above-mentioned means, each output side signal port of the 1-to-N optical distribution unit is provided with a wavelength-independent coupler, two ports of the coupler being a signal port and at least another one port. By allocating to the test monitoring port, the test monitoring light having a wavelength different from that of the signal light can be input and output without depending on the distribution number N, and the star part optical fibers can be individually or reduced without depending on the distribution number N. It becomes possible to monitor and monitor each heart.

In order to allow the test monitoring light to enter and exit the test monitoring port, an optical fiber dedicated to the test monitoring is provided, or the wavelength of the signal light and the wavelength of the test monitoring light are provided in the optical fiber of the bus section. Insert an optical multiplexing / demultiplexing component that multiplexes and demultiplexes the optical signal into / from the test monitoring port of this optical multiplexing / demultiplexing component and 1: N.
By inserting a wavelength multiplex component that gives a test monitoring light wavelength unique to each coupler, between the wavelength independent coupler test monitoring port provided in each output side signal port of the optical distribution unit It can be carried out.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In all the drawings, those having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

FIG. 1 is a schematic configuration diagram for explaining the basic configuration of an embodiment of an optical branching device with a port for test monitoring of the present invention, 6 is a wavelength independent coupler, 21 is a signal light It is a port of the wavelength-independent coupler 6 that does not contribute to propagation, and is a test monitoring port used for incidence and emission of test monitoring light, which is the main object of the present invention. Reference numeral 32 is a wavelength multiplexing device that assigns a unique test monitoring wavelength to each test monitoring port.

As shown in FIG. 1, the optical branching device with test monitoring port of this embodiment has two ports of the wavelength-independent coupler 6, which generally has four ports, as signal ports and at least other ports. One port 21 is assigned to the test monitoring port. Of the test supervisory light from the optical pulse tester 12, only the test supervisory light wavelengths assigned to each incident on the port 21 of the wavelength-independent coupler 6 and connected to the coupler 6. The backscattered light generated in 4 is emitted from the port 21 and received by the optical pulse tester 12. Therefore, instead of receiving the backscattered light from all the star part optical fibers 4 as in the prior art, the star part optical fibers 4 connected to the respective wavelength independent couplers 6 are separately received and tested and monitored. It becomes possible.

The test monitoring light can be propagated from the optical pulse tester 12 to the 1-to-N optical distribution section using the bus optical fiber 3 or another test monitoring dedicated optical fiber. When the test monitoring light propagates through the optical fiber 3 in the bus section in the same manner as the signal light, the signal light and the test monitoring light are demultiplexed.
An optical multiplexing / demultiplexing component for multiplexing may be inserted into the optical fiber 3 of the bus section.

As described above, the one-to-sixteenth which has been impossible in the past
Alternatively, it is possible to easily test and monitor more 1: N optical distribution lines.

(Embodiment 1) FIG. 2 is a schematic configuration diagram for explaining the configuration of Embodiment 1 of an optical branching device with a test monitoring port according to the present invention, and 7 is an optical fiber for test monitoring.

In the optical branching apparatus with test monitoring port of the first embodiment, as shown in FIG. 2, the test monitoring light from the optical pulse tester 12 propagates through the test monitoring optical fiber 7 and then
It is incident on each test port 21 by the wavelength division multiplexer 32. The backscattered light from each star part optical fiber 4 follows the reverse path and is received by the optical pulse tester 12. Due to such a configuration, the bus optical fiber 3 is characterized in that no special device for multiplexing / demultiplexing the test monitoring light and the signal light is required.

(Embodiment 2) FIG. 3 is a schematic constitutional view for explaining the constitution of Embodiment 2 of an optical branching device with a port for test monitoring of the present invention. The monitoring light is propagated at the same time. In FIG. 3, 31 is an optical multiplexer / demultiplexer that multiplexes and demultiplexes the wavelength of the signal light and the wavelength of the test supervisory light, and 22 is a test monitoring port of the optical multiplexer / demultiplexer 31.

In the optical branching device with test monitoring port of the second embodiment, as shown in FIG. 3, the test monitoring light from the optical pulse tester 12 is transmitted by the optical coupler 11 to the optical fiber 3 of the bus section.
Bind to. After passing through the optical fiber 3 of the bus part, the test monitoring light demultiplexed by the optical multiplexer / demultiplexer 31 enters the respective test ports 21 by the wavelength multiplexer 32 as in the first embodiment. The backscattered light from each star part optical fiber 4 follows the reverse path and is received by the optical pulse tester 12. In this case, a special optical fiber for carrying the test monitoring light to the 1: N optical distribution section 5 is not required, and the bus section optical fiber 3 has the advantage of being test-monitored.

As the wavelength division multiplexer 32 for the test monitoring light,
A combination of the directional couplers 41 as shown in FIG. 4 or a combination of the dielectric band multilayer filters 42 that transmits only the test monitoring light wavelength as shown in FIG. 5 can be applied.

According to an actual experiment, the optical pulse tester 12 equipped with four kinds of test monitoring light sources was used, and a one-to-one correspondence was obtained.
It was confirmed that 6 distributions could be measured up to 1: 4 distribution for each minority.

Although the present invention has been specifically described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

[0031]

As described above, according to the present invention, the test monitoring of the 1-to-N optical distribution type line can be realized by the passive structure without depending on the distribution number. This allows
It is expected that the failure status can be grasped and the efficiency of maintenance and operation of the optical fiber can be improved, which in turn can improve the quality of service.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining a basic configuration of an embodiment of an optical branching device with a test monitoring port of the present invention,

FIG. 2 is a schematic configuration diagram for explaining a configuration of an optical branching device with a test monitoring port according to a first embodiment of the present invention,

FIG. 3 is a schematic configuration diagram for explaining a configuration of an optical branching device with a test monitoring port according to a second embodiment of the present invention,

FIG. 4 is a diagram showing a configuration of a first test monitoring light wavelength division multiplexer according to the present embodiment;

FIG. 5 is a diagram showing a configuration of a second wavelength division multiplexer for test monitoring light according to the present embodiment;

FIG. 6 is a schematic configuration diagram showing a configuration of a conventional 1: N optical distribution line;

FIG. 7 is a schematic configuration diagram showing a configuration of test monitoring of a 1-to-N optical distribution type line according to a conventional technique,

FIG. 8 is a schematic configuration diagram showing a configuration of test monitoring when a branch coupler with a filter having a dielectric band multilayer film is used in a 1: N optical distribution unit in a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Signal light transmitting part, 2 ... Signal light receiving part, 3 ... Bus part optical fiber, 4 ... Star part optical fiber, 5 ... 1 to N optical distribution part, 6 ... Wavelength independent coupler, 7 ... Test monitoring Optical fiber, 8 ... Dielectric band multilayer filter, 11 ... Optical coupler, 12
... optical pulse tester, 21 ... port of wavelength-independent coupler 6 that does not contribute to propagation of signal light, 22 ... optical multiplexer / demultiplexer 3
1 port for test monitoring, 31 ... Optical multiplexer / demultiplexer for multiplexing / demultiplexing wavelength of signal light and wavelength of test monitoring light, 32 ... Wavelength multiplexer, 41 ... Directional coupler, 42 ... Only wavelength of test monitoring light Permeable dielectric band multilayer filter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location 8220-5K H04B 9/00 K (72) Inventor Yahei Koyamada 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo No. Japan Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. A 1-to-N optical branching device for distributing N (N> 1) of signal light incident from an incident side signal port and emitting the signal light to an outgoing side signal port. The port for use has a wavelength-independent coupler,
An optical branching device with a test monitoring port, wherein a port is assigned to a signal port and at least one other port is assigned to a test monitoring port. 2. The test monitoring port is provided with wavelength multiplexing means for individually multiplexing / demultiplexing a test monitoring wavelength having a wavelength different from that of the signal light to each emission side signal port. Optical branching device with port for test monitoring described.