JP2004109401A - Device and method for discriminating optical core wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical core wire discriminating device/method for detecting presence of a light signal in an optical transmission line, discriminating a specified core wire without using a light source device of a special wavelength and discriminating presence of the specified light signal without affecting a light transmission state of a present line in PDS (PON) communication. <P>SOLUTION: The optical core wire discriminating device is provided with a bend application part 10 which partially bends an optical fiber 1 and leaks the light signal, a light receiving element 11 detecting leaked light and a detection circuit 13 amplifying and discriminating received leaked light. Wavelength selection filters 10, 1a and 10b are arranged on a light receiving face side of the light receiving element 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber discrimination device and an optical fiber discrimination method used for performing optical fiber contrast, hot wire determination, and the like of an optical transmission line.
[0002]
[Prior art]
When laying an optical cable or the like, it is necessary to identify and specify an optical fiber core in order to measure the optical loss of each of a plurality of optical fiber cores housed in the cable. To determine the optical fiber core, a special optical signal (for example, an optical signal modulated to a frequency of 270 Hz) is transmitted from one end of the optical cable, and light reception is detected by a light receiving element at the other end. Then, the determination is made by the detection circuit. In the detection of an optical signal by a light receiving element, an optical fiber is partially bent, and leakage light generated by bending is received and detected (for example, see Patent Document 1).
[0003]
As a device for determining an optical fiber core, a hand-type device is known (for example, see Patent Document 2). FIG. 1 is a diagram showing an example of an optical fiber identification device having a different shape from that described in Patent Document 2. FIG. 1A is a diagram illustrating a state when an optical fiber core is set, and FIG. 1B is a diagram illustrating an operation state during determination. In the drawing, 1 is an optical fiber, 2 is a main body, 3 is a head, 4 is a semicircular projection, 5 is a guide groove, 6 is a movable part, 7 is an operation knob, 8 is a display, and 9 is Shows the reset button.
[0004]
The optical fiber discrimination device illustrated in FIG. 1 has a head portion 3 on the distal end side of a main body portion 2, and is configured such that a movable portion 6 is slidably arranged facing the head portion 3. The head section 3 has a semicircular projection 4 projecting toward the movable section 6, and the projection 4 is provided with a guide groove 5 for accommodating the optical fiber 1 in a curved state. The movable section 6 has a display section 8 having a display lamp and the like on its surface, a reset button 9 and the like, and pushes out an operation knob 7 integrally provided to move the movable section 6 from the non-operation state shown in FIG. The operation state shown in FIG.
[0005]
The distal end of the movable portion 6 is formed by a concave portion having a shape adapted to the convex portion 4, and one or two light receiving elements (not shown) are provided in the concave portion. In the state shown in FIG. 1A, the optical fiber 1 is housed along the guide groove 5 of the protruding portion 4, and the optical fiber 1 is bent. Next, the operation knob 7 is pushed out to bring it into the operation state shown in FIG. 1B, the external light is shielded, and the light leaking from the optical fiber 1 bent by the head 3 is received and detected by the light receiving element. The detected leaked light is amplified and determined by a detection circuit (not shown) provided in the main unit 2 and the movable unit 6, and transmitted through the optical fiber by the display unit 8 or a buzzer (not shown). The presence or absence of an optical signal is displayed.
[0006]
[Patent Document 1]
JP 09-178945 A [Patent Document 2]
JP 08-110416 A
[Problems to be solved by the invention]
Using the above-described conventional optical fiber discriminating apparatus, let's detect a live state of an optical transmission line called PDS (Passive Double Star) communication or PON (Passive Optical Network) communication as shown in FIG. And In PDS (PON) communication, a downstream optical signal λ1 from an OLT (Phone Office Optical Line Terminal) is split by a splitter and transmitted to a plurality of ONUs (user home optical network units). Each of the ONUs 1 to 4 selects and acquires only the optical signal addressed to itself. The downstream optical signal λ1 also includes a signal for controlling the transmission timing of the upstream optical signal λ2 from each of the ONUs 1 to ONU4.
[0008]
Each of the ONUs 1 to 4 transmits an upstream optical signal λ2 at a transmission timing designated by the OLT. Each optical signal λ2 transmitted from each of the ONUs 1 to 4 enters the OLT as a signal train T at a timing designated by the OLT and combined by the splitter. In the OLT, the signal sequence T of the upstream optical signal λ2 is divided into optical signals for each of ONU1 to ONU4.
[0009]
Here, for example, there is an application for abolition of OUN1, and an attempt is made to remove the line between the splitter and OUN1. In this case, the determination of which port of the splitter OUN1 is connected to is normally made at the point X on the exit side of the splitter. In practice, this is performed by opening a closure for connecting or branching an optical cable. If the above-described optical fiber identification device is used for this line determination, the upstream optical signal λ1 is transmitted from the OLT side even if the power of the OUN1 is turned off and the optical signal λ2 is not transmitted. The leaked light of the optical signal λ1 is detected and regarded as a live state, and the line of OUN1 cannot be specified.
[0010]
Also, a special optical signal (for example, an optical signal modulated to a frequency of 270 Hz) different from the optical signals λ1 and λ2 is input from the OUN1 side into the line, and the leaked light is detected at point X to compare the lines. It is possible. However, it is necessary to prepare an expensive light source device for transmitting modulated light of a special wavelength to the OUN 1 side, and the modulated light may enter the OLT and adversely affect it, which is not practical. Further, the levels of the leaked light received by the two light receiving elements provided on the left and right are compared, and the direction of the optical signal is detected, and the optical signal λ1 from the OUN1 side or the optical signal λ2 from the OLT side is used. Although a method of determining whether or not there is, it is conceivable, but accurate determination is difficult because it is easily affected by disturbance light or the like.
[0011]
The present invention has been made in view of the above-described circumstances, and can determine a specific core by detecting the presence or absence of an optical signal in an optical transmission line without using a light source device having a special wavelength. It is another object of the present invention to provide an optical fiber identification device and an identification method capable of determining the presence or absence of a specific optical signal without affecting the optical transmission state of a working line in PDS (PON) communication.
[0012]
[Means for Solving the Problems]
An optical fiber identification device according to the present invention includes a bending portion for partially bending an optical fiber to leak an optical signal, a light receiving element for detecting leaked light, and a detection circuit for amplifying and determining the received leaked light. And a wavelength selecting filter provided on a light receiving surface side of the light receiving element.
[0013]
In addition, in the optical fiber identification method according to the present invention, an optical fiber is partially bent by a bending portion to leak an optical signal, the leaked light is detected by a light receiving element, and the detected leaked light is amplified by a detection circuit and determined. In this method, the leaked light is detected by a light receiving element via a wavelength selection filter.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an example of an optical fiber discrimination device used in the description of the prior art, FIG. 2 (A) is a diagram showing an example of the present invention, and FIG. 2 (B) is a diagram showing another example of the present invention. It is. In the figure, 1 is an optical fiber, 10 is a bending portion, 11 is a light receiving element, 12, 12a and 12b are wavelength selection filters, and 13 is a detection circuit.
[0015]
The optical fiber identification device according to the present invention can be configured in a shape as shown in FIG. 1 in the same manner as described in the section of the prior art. That is, the optical fiber discrimination device includes the head unit 3 on the distal end side of the main body 2, and the movable unit 6 is slidably arranged facing the head unit 3. The head section 3 has a semicircular projection 4 projecting toward the movable section 6, and the projection 4 is provided with a guide groove 5 for bending and storing the optical fiber 1.
[0016]
The movable section 6 has a display section 8 and a reset button 9 on its surface, and pushes the operation knob 3 provided integrally from the front, so that the non-operating state of FIG. It can be in the operating state. When the operating state is set, the external light is shielded, and the light leaking from the optical fiber 1 which is bent by being accommodated in the guide groove 5 of the head portion 3 is detected by the light receiving element 11 (see FIG. 2). The detected leakage light is amplified and determined by a detection circuit 13 (see FIG. 2) provided in the main body 2 and the movable section 6, and the result is displayed by the display section 8 or a buzzer (not shown). .
[0017]
The distal end of the movable portion 6 is formed by a concave portion having a shape conforming to the convex portion 4, and forms a bending portion 10 of the optical fiber 1 as shown in FIG. For example, two light receiving elements 11 are arranged on the left and right sides of the concave portion on the movable portion 6 side, and approach the optical fiber 1 bent by the bending applying portion 10 to receive the leaked light from the optical fiber 1. To detect. Note that one light receiving element 11 may be provided, but by using two light receiving elements 11, the direction of the signal light can be determined. That is, in the bending applying unit 10, the leakage light detected in the first bend is larger than the leakage light detected in the next bend, and the level of the leakage light detected by the two light receiving elements 11 is compared. The direction of the optical signal can be determined.
[0018]
In the present invention, light leaked from the optical fiber 1 is received on the light receiving surface side of the light receiving element 11 via the wavelength selection filter 12. As the wavelength selection filter 12, for example, various filters such as a dielectric multilayer film can be used. By arranging the wavelength selection filter 12 on the light receiving surface side of the light receiving element 11 by a method or the like, it becomes possible to detect only an optical signal of a specific wavelength leaking at the bending applying portion 10. That is, in wavelength division multiplexing communication, the presence or absence of an optical signal in a specific wavelength band can be detected.
[0019]
In the present invention, as shown in FIG. 2B, at least two light receiving elements 11 are provided, and wavelength selection filters 10a and 10b having different wavelengths are arranged on the light receiving surface side of each light receiving element. it can. Thus, for example, the light receiving element 11 on the left side of the figure can detect and receive only the wavelength λa, and the light receiving element 11 on the right side can detect and receive only the wavelength λb. Note that a configuration may be adopted in which the wavelength selection filter is not disposed on one of the light receiving elements.
[0020]
The detection circuit 13 includes switching means for switching the detection of the wavelength λa and the detection of the wavelength λb, and it is also possible to discriminate between optical signals of two different wavelengths and to check the presence or absence of the optical signal. The number of light receiving elements 11 is not limited to two, and three or more light receiving elements may be provided. Wavelength multiplexed optical transmission is performed by arranging a wavelength selection filter having a different selection wavelength in each light receiving element and switching detection. It is also possible to select an optical signal of a specific wavelength band from the line and check for the presence or absence of the optical signal.
[0021]
The optical fiber discrimination device of FIG. 2A configured as described above is used to perform the core discrimination at the point X on the exit side of the splitter while maintaining the current communication state on the PDS (PON) communication line of FIG. Suppose you used it to do it. Then, it is assumed that a wavelength selection filter that can select the wavelength band of the downstream optical signal λ2 is used. For example, it is assumed that there is an application for abolition of OUN1, and the line of OUN1 is determined at point X on the exit side of the splitter in order to remove the lines from splitter to OUN1.
[0022]
In this case, it is assumed that the ONU 1 is turned off and is in a non-use state, and the OLT and the ONUs 2 to 4 are in a normal use state. Since the wavelength selection filter 12 is selected to transmit only the wavelength of the upstream optical signal λ2, the downstream optical signal λ1 from the OLT is not detected. Further, since the upstream optical signal λ2 is not transmitted from the ONU 1, the upstream optical signal λ2 is not detected at the point X. As a result, no optical signal is detected at the point X, and it can be specified that the optical fiber is the core of the ONU1 line. In the other ONUs 2 to 4, the upstream optical signal λ2 is detected, and it is determined that the ONU 2 is ON. In order to ensure safety, the upstream signal λ2 is detected at the point X when the power supply of the ONU 1 is turned on, and the upstream optical signal λ2 is not detected at the point X when the power supply of the ONU 1 is turned off again. Check it out.
[0023]
Further, the optical fiber discrimination device configured as shown in FIG. 2B performs the fiber discrimination at the exit X point of the splitter while maintaining the current communication state on the PDS (PON) communication line of FIG. Suppose you used it. For example, one of the wavelength selection filters 12a can detect the upstream optical signal λ2, and the other wavelength selection filter 12b can detect the downstream optical signal λ1. Similarly to the above, there is an application for abolition of OUN1, and in order to remove the lines from the splitter to the OUN1, the core of the OUN1 is determined at the point X at the exit of the splitter.
[0024]
In this case, it is assumed that the ONU 1 is turned off and is in a non-use state, and the OLT and the other ONUs 2 to 4 are in a normal use state. The downstream optical signal λ1 from the OLT is detected by the wavelength selection filter 12b at the point X of the ONU1 line, and the communication line is determined to be in a live state. However, since the upstream optical signal λ2 is not transmitted from the ONU1, the optical signal λ2 is not detected on the wavelength selection filter 12a side, and it can be specified that the optical fiber is the core of the ONU1 line. Each of the other ONUs 2 to 4 detects both the downstream optical signal λ1 and the upstream optical signal λ2, and is determined to be in a live state.
[0025]
【The invention's effect】
As described above, according to the present invention, the presence / absence of an optical signal in a specific wavelength band can be checked, and the core wire can be easily specified. Also, it is possible to determine the presence or absence of an optical signal of a specific wavelength band in wavelength division multiplexing communication. Further, in a PDN (PON) line, the presence / absence of an ONU and the contrast of the line can be determined without affecting the communication state of the working line. The determination can be made reliably at the splitter portion.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an optical fiber identification device.
FIG. 2 is a diagram illustrating an embodiment of the present invention.
FIG. 3 is a diagram illustrating a PDS (PON) communication line.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 2 ... Body part, 3 ... Head part, 4 ... Semicircular protrusion part, 5 ... Guide groove, 6 ... Movable part, 7 ... Operation knob, 8 ... Display part, 9 ... Reset button, 10: Bending section, 11: Light receiving element, 12, 12a, 12b: Wavelength selection filter, 13: Detection circuit.

Claims (4)

An optical fiber discriminating apparatus including a bending imparting unit that partially bends an optical fiber to leak an optical signal, a light receiving element that detects leaked light, and a detection circuit that amplifies and determines the received leaked light, An optical fiber identification device, comprising: a wavelength selection filter on a light receiving surface side of the light receiving element. The optical fiber discriminating apparatus according to claim 2, further comprising at least two light receiving elements, and a wavelength selection filter having a different wavelength range on each light receiving surface. An optical fiber discrimination method in which an optical signal is leaked by partially bending an optical fiber by a bend imparting unit, the leaked light is detected by a light receiving element, and the detected leaked light is amplified and determined by a detection circuit. An optical fiber discrimination method, wherein the leakage light is detected by a light receiving element via a filter. 4. The optical fiber according to claim 3, wherein the presence or absence of a user transmission unit (ONU) or a line contrast is determined on a branch side of the splitter in a passive double star (PDS) or passive optical network (PON) line. Judgment method.

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