JP4964809B2 - Optical filter presence / absence confirmation method and optical filter existence confirmation device - Google Patents

Description

  The present invention relates to the presence / absence of an optical filter in an optical line for determining the presence / absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element. The present invention relates to a confirmation method and an optical filter presence confirmation device.

  For example, in an optical access network that provides an FTTH (Fiber to the home) service that connects an office building and a user's home via an optical fiber, a network configuration (PON) with an optical branching device such as an optical splitter installed outside the office building (PON) : When using Passive Optical Network (hereinafter referred to as PON), it is provided on the user's transmission device side of the optical fiber core at the deduction point (new construction point) on the user's home side from the branch point where the optical splitter is arranged. By determining the presence or absence of the test light blocking filter, it is possible to estimate the distinction between the active optical fiber core and the non-active optical fiber core.

  The working optical fiber core wire means an optical fiber core wire already used by a specific user, and the non-working optical fiber core wire means an optical fiber core wire not used by any user.

  This is performed in order to confirm that the working optical fiber core is not cut from the necessity of construction or the like in the optical fiber core on the user's home side from the branch point.

  In the prior art, at the new construction point of the optical fiber core below the branch point of the optical line, the optical fiber core is physically used to confirm the optical fiber core to be constructed. Therefore, it was necessary to visually and visually confirm the order and color of the optical fiber core wires.

  In the case of a single star network, the test light is incident on the non-working optical fiber from inside the office building, and the leak test light leaking from the optical fiber is detected at the new construction site. By the work (core wire contrast work), the operator could confirm the optical fiber core wire to be cut from now on.

  However, in the prior art, it is necessary to confirm the optical splitter that is far from the new construction point and confirm the color and order of the optical fiber cores that are physically wired from there. Moreover, the confirmation method by the core wire contrast work has a problem that it cannot be applied to a PON in which an optical splitter is arranged outside a station building only in the case of a single star network. .

  In addition, as a conventional technique, test light is input to an optical fiber core wire from a central office with a plurality of wavelengths, and the reflection characteristics of the test light blocking filter are used to remotely determine the level difference of the reflected light that returns. (For example, refer to Patent Document 1).

  However, the technique of Patent Document 1 is a technique that can support a single star network configuration and cannot support a PON configuration.

JP 2002-131178 A

  The present invention has been made in view of the above circumstances, and in an optical line composed of one upper optical line and a plurality of lower optical lines branched by an optical branching element, the lower optical line having excessive loss and its lower part An object of the present invention is to provide an optical filter presence / absence confirmation method and an optical filter presence / absence confirmation device for determining the presence / absence of an optical filter that blocks a specific wavelength at an end.

In order to achieve the above object , according to the present invention, there is an optical filter that blocks a specific wavelength at the lower end of an optical line composed of one upper optical line and a plurality of lower optical lines branched by an optical branching element. In the method for checking the presence or absence of the optical filter in the optical line, the incident power P ^λ1 _input and P ^λ2 are obtained from the upper end of the upper optical line by the light having the wavelength λ1 in the cutoff region and the light having the wavelength λ2 in the transmission region. Light incident step with _input power, and light incident from below the bent portion by a first power monitor portion provided on the upper side of the bent portion provided with a bent portion in the lower optical line to be determined coupling loss L _forward against, drives out coupling loss _{L back} to light incident from above the flexural portion, the wavelength .lambda.1 in the bent portion, the power P of the light leaking .lambda.2 ^.lambda.1 _{P 1,} as well as measure the P ^.lambda.2 _PD1, the second power monitor unit that is disposed on the lower side of the bent portion, coupling loss of the L _forward to light incident from above the flexural portion, the bending drives out the coupling loss of the _{L back} to light incident from the lower parts, the steps to measure the wavelength .lambda.1, power P ^λ1 _PD2, P ^λ2 _PD2 of the leakage light .lambda.2 in the bent portion, the wavelength .lambda.1 Approximate calculation according to the following equations (9) to (11) is performed with the ratio ΔP _LD of the incident power P ^λ1 _input and P ^λ2 _input power of the light of wavelength λ2 and the light of wavelength λ2 entering the optical line as known, and the judgment value ΔP ′ There is provided a method for checking the presence or absence of an optical filter in an optical line, comprising the step of determining the presence or absence of an optical filter using _PD1 .
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11)

According to the present invention, there is provided an optical line for determining the presence or absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element. In the optical filter presence / absence confirmation device, light of wavelength λ1 in the cutoff region of the optical filter and light of wavelength λ2 in the transmission region are incident at the power of the incident powers P ^λ1 _input and P ^λ2 _input from the upper end of the upper optical line. Light incident means and an upper portion of a bent portion provided in the lower optical line to be judged, L _forward coupling loss with respect to light incident from below the bent portion, light incident from above the bent portion drives out coupling loss _{L back} against a first Pawamoni data means to measure the wavelength .lambda.1, power P ^λ1 _PD1, P ^λ2 _PD1 of the leakage light .lambda.2 at the bending portion, the bending portion The L _forward coupling loss with respect to the light incident from above the bent portion, and the L _back coupling loss with respect to the light incident from below the bent portion , wavelength .lambda.1 at bent portions, the power P ^.lambda.1 _PD2 of leakage light .lambda.2, P ^.lambda.2 _PD2 and second Pawamoni data means to measure, and light of wavelength .lambda.1, incident power P ^.lambda.1 to light the light path of the wavelength .lambda.2 _input , P ^λ2 The power ratio ΔP _LD of the _input is known, and approximate calculation is performed by the above formulas (9) to (11), and the presence / absence of the optical filter is determined using the determination value ΔP ′ _PD1. An optical filter presence / absence confirmation device for an optical line is provided .

According to the present invention, there is provided an optical line for determining the presence or absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element. In the optical filter presence / absence confirmation method, the modulated light obtained by modulating the light of wavelength λ1 in the cutoff region of the optical filter from the upper end of the upper optical line at the frequency f1 and the light of wavelength λ2 in the transmission region are modulated by the frequency f2. A light incident step for injecting modulated light at powers of incident powers P ^λ1 _input and P ^λ2 _input , and a first power monitor unit disposed on the upper side of the bent portion by providing a bent portion in the lower optical line to be determined the coupling loss of L _forward to light incident from below the said bending portion, drives out coupling loss L _back to light incident from above the flexural portion, in the bent portion The power P ^.lambda.2 _PD1 light modulated leakage light at the frequency f2 of the light and power P ^.lambda.1 _PD1 leakage light modulated at frequency f1 wavelength .lambda.2 length .lambda.1 while measurement, the lower side of the bent portion The second power monitor unit disposed has a coupling loss of L _forward with respect to light incident from above the bent portion and a coupling loss of L _back with respect to light incident from below the bent portion. I, a step of light of wavelength .lambda.1 to measure the power P ^.lambda.2 _PD2 leakage light the light is modulated at a frequency f2 of the power P ^.lambda.1 _PD2 and the wavelength .lambda.2 modulated leakage light at the frequency f1 in the bent portion performs a light of wavelength .lambda.1, incident power P ^.lambda.1 _{input the} to light the light path of the wavelength .lambda.2, the approximate calculation according to the above formula the ratio [Delta] P _LD power of P ^.lambda.2 _{input the} as known (9) - (11) Optical filter presence check method of the ray path, characterized in that it comprises a step of determining whether the optical filter drives out judgment value [Delta] P _'PD1 is provided.

According to the present invention, there is provided an optical line for determining the presence or absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element. In the optical filter presence / absence confirmation device, the modulated light obtained by modulating the light of wavelength λ1 in the cutoff region of the optical filter from the upper end of the upper optical line at the frequency f1 and the light of wavelength λ2 in the transmission region are modulated by the frequency f2. Light incident means for entering the modulated light with the power of incident powers P ^λ1 _input and P ^λ2 _input , and the upper side of the bending portion provided in the lower optical path to be judged, and the light incident from below the bending portion coupling loss L _forward against, drives out coupling loss L _back to light incident from above the the bending portion, of the leaked light light of the wavelength λ1 at the bending portion is modulated at a frequency f1 A first Pawamoni data hand stage light word P ^.lambda.1 _PD1 and the wavelength .lambda.2 measures the power P ^.lambda.2 _PD1 modulated leakage light at the frequency f2, is disposed on the lower side of the bending portion, the upper the bending portion The light having the wavelength λ1 in the bent portion is modulated at the frequency f1 with the coupling loss of the L _forward with respect to the light incident from the above and the coupling loss of the L _back with respect to the light incident from below the bent portion. a second Pawamoni data hand stage optical power P ^.lambda.1 _PD2 and the wavelength .lambda.2 leakage light is measured power P ^.lambda.2 _PD2 modulated leakage light at the frequency f2, the light of wavelength .lambda.1, light of the wavelength .lambda.2 Approximate calculation according to the above formulas (9) to (11) is performed with the power ratio ΔP _LD of the incident powers P ^λ1 _input and P ^λ2 _input to the known optical line as known, and the optical filter of the optical filter is determined by the determination value ΔP ′ _PD1 Yes Light path of the optical filter presence confirmation apparatus characterized by comprising a means for determining is provided.

Further, the present invention relates to the method for confirming the presence or absence of an optical filter in the optical line, wherein a ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light of wavelength λ1 and the light of wavelength λ2 to the optical line is expressed by the following formula ( 11 ′), and approximate calculation according to equations (9) to (10) is performed using the power ratio ΔP _LD .
ΔP _LD = P ^λ1 _PD2 ÷ P ^λ2 _PD2 (11 ′)

In the optical line filter presence / absence confirmation device according to the present invention, a power ratio ΔP _LD of incident powers P ^λ1 _input and P ^λ2 _input to the optical line of the light of wavelength λ1 and the light of wavelength λ2 is expressed by the following equation (11). ′), And the approximate calculation according to the equations (9) to (10) is performed using the power ratio ΔP _LD .

Further, the present invention is characterized in that, in the optical filter presence / absence confirmation method for the optical line, the judgment value ΔP ′ _PD1 is approximately calculated by the following equation (9 ′).
^{_{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ (P λ2 PD1 × ΔP LD × α) (9')
Where α is a constant

Further, the present invention is characterized in that, in the optical line optical filter presence / absence confirmation device, the determination value ΔP ′ _PD1 is approximately calculated by the equation (9 ′).

  The optical filter presence / absence confirmation method and the optical filter presence / absence confirmation device according to the present invention have a loss below the determination point, which is difficult in the prior art, in a PON network configuration having an optical branching element outside the office building. If it is large, confirm the working / non-working of the branching lower optical line at the new construction point on the user's home side from the branching point by applying an approximate calculation to eliminate the influence of the incident test light Can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing a configuration of an optical filter presence / absence confirmation system according to an embodiment of the present invention, and shows a configuration of a PON that realizes FTTH.

  As shown in FIG. 1, a two-wavelength light source 12 for generating light of wavelengths λ1 and λ2 and a transmission device (OLT: Optical Line Terminal) 13 are provided in a station 11 of a communication station. The light source 12 and the transmission device 13 are connected to a test light inserting optical coupler 14 through an optical line. The optical coupler 14 for inserting test light is connected to an optical splitter 16 for branching light outside the station 11 by an optical fiber cable 15 constituting one upper optical line, and the first splitter of the optical splitter 16 is connected to the optical splitter 16. An optical fiber core wire (opening core wire) 17 that constitutes the lower optical line passes through a test light blocking filter 18 such as an FBG filter that blocks test light having a specific wavelength at the lower end of the optical line and transmits communication light. A user transmission device (ONU: Optical Network Unit, optical subscriber line terminating device) 19 is connected. Since it is necessary to perform an optical pulse test for testing the optical fiber core wire constituting the lower optical line, the test light blocking filter 18 is transmitted to the user so that the test light is not received by the user transmission device 19 and causes an error. Insert just before the device 19.

  At the second branching portion of the optical splitter 16, test light having a specific wavelength is blocked by a working optical fiber core wire (opening core wire) 20 constituting a lower optical line and communication light is transmitted, for example, test light such as an FBG filter. A user transmission device (ONU: Optical Network Unit, optical subscriber line termination device) 22 is connected via a cutoff filter 21. Since it is necessary to perform an optical pulse test for testing the optical fiber core wire constituting the lower optical line, the test light blocking filter 21 is transmitted to the user so that the test light is not received by the user transmission device 22 and causes an error. Insert just before the device 22.

  A non-working optical fiber core wire (unopened core wire) 23 constituting a lower optical line is connected to the third branch portion of the optical splitter 16, and the end portion of the non-working optical fiber core wire 23 is cut off. Alternatively, it is terminated by a connector and treated as a so-called open end 24.

  A construction target optical fiber 25 constituting a lower optical line is connected to the fourth branch portion of the optical splitter 16, and the construction target optical fiber 25 is bent with a coupling loss corresponding to the light input direction. A portion 26 is provided.

  The bent portion 26 is provided with a first photoelectric conversion element 28 such as a photodiode PD1 and a second photoelectric conversion element 29 such as a photodiode PD2 of the non-working confirmation device 27.

  The output terminal of the first photoelectric conversion element 28 is connected to the input terminal of a first power monitor unit (upstream optical power monitor unit) 30, and the output terminal of the first power monitor unit 30 is, for example, a memory or a determination logic. Connected to the filter discrimination processing unit 31 to which an approximate calculation including the above is applied. An output end of the second photoelectric conversion element 29 is connected to an input end of a second power monitor unit (downlink optical power monitor unit) 32, and an output end of the second power monitor unit 32 is a filter discrimination processing unit 31. Connected to.

  Each of the first power monitor unit 30 and the second power monitor unit 32 includes a corresponding band filter for identifying the frequencies f1 and f2 (f1 / f2 identification). In FIG. 1, a dotted line 33 indicates a new construction point.

  That is, by utilizing the fact that the equipment configuration differs depending on the working optical fiber core or the non-working optical fiber core, specifically, depending on the presence or absence of the test light blocking filter, the working optical fiber core wire or the non-working optical fiber core wire This is to make a determination.

  In the present embodiment, a tester who performs a test using the two-wavelength light source 12 and a worker who works at the new construction point 33 are dispatched from inside the station 11, and the tester and the worker have communication means with each other. Is.

  A tester inputs light having a light wavelength λ <b> 1 and a light wavelength λ <b> 2 from the test light insertion optical coupler 14 in the office 11 to the construction target optical fiber core 25 by the two-wavelength light source 12. The two-wavelength light source 12 may be continuous light or modulated light modulated at frequencies f1 and f2. (However, in the case of continuous light, simultaneous input of two-wavelength light is not possible.)

The operator receives the input light by the non-working confirmation device 27.
The non-working confirmation device 27 can detect the test light leaked by the bending unit 26 with the first power monitor unit 30 and the second power monitor unit 32. The first power monitor unit 30 can detect the test light that leaks in the input direction in which the input direction of the test light mainly travels from the user's home side toward the station 11 side . The second power monitor unit 32 The test light leaks with respect to the input direction in which the light input direction is mainly from the station 11 side toward the user house side .

The power levels received by the first power monitor unit 30 and the second power monitor unit 32 in the non-working confirmation device 27 at this time are expressed by the following equations. In both formulas (1) and (2), the first term represents the component of the incident test light, and the second term represents the component of the reflected test light.
_{P PD1 = (P in ÷ L} back) + (P in ÷ L E ÷ L 2 ÷ γ ÷ L forward) (1)
_{P PD2 = (P in ÷ L} forward) + (P in ÷ L E ÷ L 2 ÷ γ ÷ L back) (2)

  FIG. 2 is an explanatory diagram showing the light receiving level of the photoelectric conversion element according to the embodiment of the present invention, and FIG. 3 is an explanatory diagram showing the line loss of the optical filter presence confirmation system according to the embodiment of the present invention.

As shown in FIGS. 2 and 3, P _PD1 is a power level received by the first power monitor unit 30 (light reception level of the first photoelectric conversion element 28), and P _PD2 is received by the second power monitor unit 32. to power level (received light level of the second photoelectric conversion element 29), P _in the non-working check device 27 before the input power, L _E is the insertion loss of the non-working check device 27, L ₁ is up to the new work point 33 loss of optical lines (excluding optical splitter 16), SP loss of the optical splitter 16, _{L 2} is round trip losses from new construction point 33 to the optical line far end, gamma loss in the far-end reflection _{portion, L forward} light Loss for coupling to a power monitor unit that exists in the forward direction with respect to the input direction of L, and L _back is a loss for coupling to the power monitor unit that exists in the opposite direction to the input direction of light. Represents.

_{Further, P in} a dual wavelength light source 12 power _{P input The} light inputted to the optical line from
P _in = P _input ÷ L ₁ ÷ SP
Holds. These power and loss values are all linearly displayed in the relational expressions. The same applies to the following.
As will be described later, the loss of γ varies greatly depending on the light wavelength and the presence or absence of the test light blocking filter.
The subscripts λ1 and λ2 indicate the optical loss and power at the optical wavelengths λ1 and λ2, respectively.

In addition, as a condition of input power,
In order not to affect the user home transmission device,
P ^λ1 _input ÷ A ≧ P ^λ2 _input
It is necessary to satisfy.
A represents a cutoff amount that does not affect the user transmission device. The test light blocking filter differs in its blocking amount depending on the type, but in the case of a filter using FBG, it has approximately 30 dB or more, so A = 1000.
Further, when the cutoff amount is 20 dB, A = 100.

FIG. 4 is a reflection characteristic diagram showing the wavelength dependence of the test light blocking filter / open end according to the embodiment of the present invention.
The test light blocking filter has a wavelength characteristic as shown by a solid line in FIG. 2 in order to block specific test light and allow other light to pass. At the wavelength λc, it has a high reflection characteristic, and on the other hand, almost all light passes through wavelengths shorter than the wavelength λL or longer than λH. About the return loss ,
γ ^λ1 = 0.24 (dB)
γ ^λ2 ≈ 20 to 30> 14.6 (dB) (λ <λL or λ> λH)
It becomes.

In addition, reflection at different surfaces of the medium, so-called Fresnel reflection, occurs at the open end. Since Fresnel reflection has almost no wavelength dependence, it is as shown by a broken line in FIG. 4 and its reflection attenuation is about 14.6 (dB).

Therefore, λ1 can be set in the vicinity of λc having high reflection characteristics of the test light blocking filter, and λ2 can be set to λ2 <λL or λ2> λH. In FIG. 4 , it is set on the shorter wavelength side than λL.

Here, the power level ratio ΔP _PD1 of the first power monitor unit 30 due to the difference in wavelength including far-end reflection is used as the determination value. That is,
From the formula (1) / (2), ΔP _PD1 = P ^λ1 _PD1 ÷ (P ^λ2 _PD1 × ΔP _LD ) = ((P ^λ1 _in ÷ L _back ) + (P ^λ1 _in ÷ L ^λ1 _E ÷ L ^λ1 ₂ ÷ γ ^λ1 ÷ L _forward )) ÷ ( ((P ^λ2 _in ÷ L _back ) + (P ^λ2 _in ÷ L ^λ2 _E ÷ L ^λ2 ₂ ÷ γ ^λ2 ÷ L _forward ) ) × ΔP _LD ) (3)
It becomes. ΔP _LD is the ratio of the incident power P ^λ1 _input of the light of wavelength λ1 to the incident power P ^λ2 _input of the light of wavelength λ2.
If L ₂ is smaller optical line loss, the value of the equation (3), by the difference of the filter presence, for large change can be determined filter presence.

However, in the case of an optical line with a large loss of L ₂ , the first term and the third term on the right side of Equation (3) become dominant, so the value of Equation (3) decreases as L ₂ increases. Therefore, it becomes difficult to set a threshold value for determining the presence or absence of a filter.
Therefore, the first term and the third term on the right side, which are the incident test components, are newly removed, and a determination value ΔP ′ _PD1 based on the ratio between the second term and the fourth term on the right side, which is the reflected test light component, is introduced.

That is, by taking the difference of only the reflected test light component, and eliminating the influence of the lower loss L _2.
First, the (λ1-λ2) inter-wavelength level ratio ΔP ′ _PD1 of the first power monitor unit 30 excluding the incident test component can be described by the equation (4).
^{_{(P λ1 PD1 - (P λ1}} in ÷ L back)) ÷ ΔP 'PD1 = (P λ2 PD1 - (P λ2 in ÷ L back)) × ΔP LD (4)

The power levels of (P ^λ1 _in ÷ L _back ) and (P ^λ2 _in ÷ L _back ) are set to the levels of P _PD1 and P _PD2 of λ2 and the incident power P ^λ1 _input of light of wavelength λ1 and the incidence of light of wavelength λ2 It is estimated using the ratio ΔP _LD of the power P ^λ2 _input .
P ^λ2 _PD2 ÷ P ^λ2 _{PD1
^{= ((P λ2 in ÷ L}} forward) + (P λ2 in ÷ L λ2 E ÷ L λ2 2 ÷ γ λ2 ÷ L back)) ÷ ((P λ2 in ÷ L back) + (P λ2 in ÷ L λ2 E ÷ L ^λ2 ₂ ÷ γ ^λ2 ÷ L _forward )) (5)

Here, assuming that the second term and the fourth term on the right side in equation (5) are sufficiently smaller than the first term and can be ignored, equation (5) can be modified as follows.
P ^λ2 _PD2 ÷ P ^λ2 _PD1
= (P ^λ2 _in ÷ L _forward ) ÷ (P ^λ2 _in ÷ L _back ) = L _back ÷ L _forward = ΔL (6)
In the equation (6), the ratio between L _back and L _forward is ΔL.

Next, considering the PD2 light receiving level of λ2 in the same way,
P ^λ2 _PD2 = (P ^λ2 _in ÷ L _forward )
And
_{^{(P λ2 in ÷ L back)}} = (P λ2 in ÷ L forward) ÷ ΔL = P λ2 PD2 ÷ ΔL (7)
Holds. Also, using ΔP _LD ,
P ^λ2 _in = (P ^λ1 _in ÷ ΔP _LD ) (8)
It is. Equation (8) assumes that the optical splitter loss and the L1 loss do not change depending on the wavelengths λ1 and λ2.

Accordingly, when the equation (4) is transformed using the equations (6) to (8), the following equation is obtained.
^{_{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11)

In the case a spacing wavelengths λ1 and λ2 are close, for cable loss value and splitter losses due to wavelength difference are almost the _{same, SP, L E, L 1} , L 2, L back, L forward the wavelength difference Depending on the value.

  By using the equation (9) as a determination value, the (λ1-λ2) inter-wavelength power level difference in the first power monitor unit 30 excluding the incident test light component can be obtained, and the lower light beam having an excessive loss. The presence or absence of an optical filter that blocks a specific wavelength at the path and its lower end can be determined.

That is, ΔP ′ _PD1 is obtained based on the equations (9) to (11),
If ΔP _'of the _PD1 »1, there is a filter,
When ΔP ′ _PD1 ≈1, it is determined that there is no filter.

Further, when the dynamic ranges of the first power monitor unit 30 and the second power monitor unit 32 are small, the value of the second term on the right side may be 0 in the above equation (9). In other words, it has become a _{^{(P λ2 PD1 <(P λ2}} PD2 ÷ ΔL)). This is because the reflection test light component of the incident test light component and the reflection test light component having the value of P ^λ2 _PD1 is very small compared to the incident test light component.
Therefore, the following equation (9 ′) can be used instead of the above equation (9).
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ (P λ2 PD1 × ΔP LD × α) (9')
Where α is a constant (α <0.15)
α is the ratio of the incident test light component and the reflected test light component input to PD1. Although it differs depending on the reflection condition, it is approximately 0.15 or less in the worst condition Fresnel reflection condition.

Also, ΔP _LD is not known, but can be estimated from the values of P ^λ1 _PD2 and P ^λ2 _PD2 . That is, approximate calculation can be performed using the following equation (11 ′) instead of the above equation (11). Setting is unnecessary by _obtaining ΔP _LD from the measured values P ^λ1 _PD2 and P ^λ2 _PD2 .
ΔP _LD = P ^λ1 _PD2 ÷ P ^λ2 _PD2 (11 ′)

5 and 6 are flowcharts showing an optical filter presence / absence confirmation method according to an embodiment of the present invention. First, ΔP _LD is set at the start. In step S1, the tester inserts the optical wavelength λ1 from the test light inserting optical coupler 14 at the upper end of the optical fiber cable 15 in the station 11 to the construction target optical fiber 25 by the two-wavelength light source 12. Enter the test light with. The test light from the two-wavelength light source 12 may be continuous light or modulated light modulated at the frequency f1.

  If modulated light modulated at a specific frequency f1 is used, band filters corresponding to the modulation frequencies are provided corresponding to the first power monitor unit 30 and the second power monitor unit 32 of the non-working confirmation device 27, respectively. Thus, only the modulated light can be detected. For this reason, for example, there is no influence of other light in accordance with continuous light such as signal light, and there is an effect that measurement of modulated light becomes more reliable.

  In step S <b> 2, the operator receives the leakage light from the test light input to the construction target optical fiber 25 at the new construction point 33 by the non-working confirmation device 27.

  In step S3, if the first photoelectric conversion element 28 and the second photoelectric conversion element 29 cannot receive light (NO), the cause is analyzed in step S4, the target error, excessive loss occurs, and the light receiving sensitivity is insufficient. Etc., and return to step S1 to remeasure.

In step S3, if light can be received by the first photoelectric conversion element 28 and the second photoelectric conversion element 29 (YES), it is recorded in the memory of the filter discrimination processing unit 31 in step S5. That is,
ΔP1 ₋ λ1 (PD1) = ^Pλ1 _PD1
ΔP1 ₋ λ1 (PD2) = P ^λ1 _PD2

  Next, in step S6, the tester inserts the test light insertion optical coupler 14 at the upper end of the optical fiber cable 15 in the station 11 from the optical fiber core wire 25 to the construction target optical fiber 25 by the two-wavelength light source 12. Test light having an optical wavelength λ2 is input. The test light from the two-wavelength light source 12 may be continuous light or modulated light modulated at the frequency f2.

  If modulated light modulated at a specific frequency f2 is used, band filters corresponding to the modulation frequencies are provided corresponding to the first power monitor unit 30 and the second power monitor unit 32 of the non-working confirmation device 27, respectively. Thus, only the modulated light can be detected. For this reason, for example, there is no influence of other light in accordance with continuous light such as signal light, and there is an effect that measurement of modulated light becomes more reliable.

  In step S7, the worker receives leaked light from the test light input to the construction target optical fiber 25 at the new construction point 33 by the non-working confirmation device 27 (the bending state is maintained).

  In step S8, if the first photoelectric conversion element 28 and the second photoelectric conversion element 29 cannot receive light (NO), the cause is analyzed in step S9, and excessive loss is generated, light reception sensitivity is insufficient, etc. Then, the process returns to step S1 and remeasures.

If the first photoelectric conversion element 28 and the second photoelectric conversion element 29 have received light (YES) in step S8, they are recorded in the memory of the filter discrimination processing unit 31 in step S10. That is,
ΔP2 ₋ λ2 (PD1) = ^Pλ2 _PD1
ΔP2 ₋ λ2 (PD2) = ^Pλ2 _PD2
In step S11, by comparing the power level difference due to difference in wavelength by the filter determining process unit 31, calculates the ΔL and [Delta] P _'PD1. That is,
ΔL = ΔP2 ₋ λ2 (PD2) ÷ ΔP2 ₋ λ2 (PD1)
ΔP ′ _PD1 = (ΔP1 ₋ λ1 (PD1) − (ΔP2 ₋ λ2 (PD2) ÷ ΔL × ΔP _LD )) ÷ ((ΔP2 ₋ λ2 (PD1) − (ΔP2 ₋ λ2 (PD2) ÷ ΔL)) × ΔP _LD )

  Next, in steps S12 and S14, the filter discrimination processing unit 31 compares the power level difference in the vertical direction of the optical line.

If ΔP ′ _PD1 >> 1 in step S12, it is determined in step S13 that there is a test light blocking filter (FBG filter) at the lower end portion of the target optical line, and the processing is completed after confirming that the optical fiber core is in use. To do.

On the other hand, in step S12, [Delta] P _'instead of _PD1 >> 1, in step S14, [Delta] _P' if _PD1 ≒ 1, in step S15, no test light blocking filter (FBG filter) at the lower end of the optical line of interest It is judged, and it confirms with the non-working optical fiber core wire, and ends.

If ΔP ′ _PD1 ≈1 is not _satisfied in step S14, the process returns to step S1 as a gray zone (error display) and is measured again.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

It is composition explanatory drawing which shows the optical filter presence / absence confirmation system which concerns on one Embodiment of this invention. It is explanatory drawing which shows the light reception level of the photoelectric conversion element which concerns on embodiment of this invention. It is explanatory drawing which shows the line loss of the optical filter presence or absence confirmation system which concerns on embodiment of this invention. It is a reflection characteristic figure which shows the wavelength dependence of the test light cutoff filter and open end which concern on embodiment of this invention. It is a flowchart which shows the optical filter presence / absence confirmation method which concerns on embodiment of this invention. It is a flowchart which shows the optical filter presence / absence confirmation method which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Communication station building, 12 ... Dual wavelength light source, 13 ... Transmission apparatus, 14 ... Optical coupler for test light insertion, 15 ... Optical fiber cable, 16 ... Optical splitter, 17 ... Working optical fiber core wire, 18 ... Test Optical blocking filter, 19 ... user transmission device, 20 ... working optical fiber core, 21 ... test light blocking filter, 22 ... user transmission device, 23 ... non-working optical fiber core, 24 ... open end, 25 ... construction Target optical fiber core wire, 26 ... bent portion, 27 ... non-working confirmation device, 28 ... first photoelectric conversion element, 29 ... second photoelectric conversion device, 30 ... first power monitor portion, 31 ... filter discrimination processing 32, second power monitor 33, new construction point.

Claims (8)

In the optical filter presence / absence confirmation method for determining the presence / absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element,
A light incident step in which light of wavelength λ1 in the cutoff region of the optical filter and light of wavelength λ2 in the transmission region are incident at the power of incident power P ^λ1 _input and P ^λ2 _input from the upper end of the upper optical line;
The bending portion is provided in the lower beam path to be determined by the first power monitor unit that is disposed on the upper side of the bending portion, coupling loss L _forward to light incident from below the said bending portion, the bending drives out coupling loss _{L back} to light incident from above the part, with wavelength .lambda.1, to measure the power P ^λ1 _PD1, P ^λ2 _PD1 of leakage light of .lambda.2 in the bent portion, of said bent part By the second power monitor unit arranged on the lower side, the coupling loss of the L _forward with respect to the light incident from above the bent portion, and the coupling of the L _back with respect to the light incident from below the bent portion drives out losses, the steps to measure the wavelength .lambda.1, power P ^λ1 _PD2, P ^λ2 _PD2 of the leakage light .lambda.2 in the bent portion,
Approximate calculation by the following formulas (9) to (11) is performed with the ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light having the wavelength λ1 and the light having the wavelength λ2 incident on the optical line as a determination value. And a step of determining the presence / absence of an optical filter by using ΔP ′ _PD1 .
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11) In the optical filter presence / absence confirmation device for the optical line for judging the presence / absence of the optical filter for blocking a specific wavelength at the lower end portion of the optical line composed of one upper optical line and a plurality of lower optical lines branched by the optical branching element,
A light incident means for injecting light of wavelength λ1 in the cutoff region of the optical filter and light of wavelength λ2 in the transmission region from the upper end of the upper optical line with power of incident powers P ^λ1 _input and P ^λ2 _input ;
Arranged on the upper side of the bent portion provided in the lower optical line to be judged, L _forward coupling loss with respect to light incident from below the bent portion, and L _back against light incident from above the bent portion. drives out coupling loss, the first Pawamoni data means to measure the wavelength .lambda.1, power P ^λ1 _PD1, P ^λ2 _PD1 leakage light .lambda.2 at the bending portion,
It is arranged below the bent part, and has a coupling loss of L _forward with respect to light incident from above the bent part, and a coupling loss of L _back with respect to light incident from below the bent part. Te, a second Pawamoni data means to measure the wavelength .lambda.1, power P ^λ1 _PD2, P ^λ2 _PD2 of the leakage light .lambda.2 at the bending portion,
Approximate calculation by the following formulas (9) to (11) is performed with the ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light having the wavelength λ1 and the light having the wavelength λ2 incident on the optical line as a determination value. Means for determining the presence or absence of an optical filter by using ΔP ′ _PD1 .
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11) In the optical filter presence / absence confirmation method for determining the presence / absence of an optical filter that blocks a specific wavelength at the lower end of an optical line composed of a single upper optical line and a plurality of lower optical lines branched by an optical branching element,
The modulated light obtained by modulating the light of wavelength λ1 in the cutoff region of the optical filter from the upper end of the upper optical line with the frequency f1 and the modulated light obtained by modulating the light of wavelength λ2 in the transmission region with the frequency f2 are incident power P ^λ1. _input , a light incident step that is incident at a power of P ^λ2 _input ;
The bending portion is provided in the lower beam path to be determined by the first power monitor unit that is disposed on the upper side of the bending portion, coupling loss L _forward to light incident from below the said bending portion, the bending The power P ^λ1 _PD1 and the light of wavelength λ2 of the leaked light in which the light of wavelength λ1 in the bent portion is modulated at the frequency f1 with the coupling loss of L _back with respect to the light incident from above the portion is the frequency f2. together to measure the power P ^.lambda.2 _PD1 of the modulated optical leakage in the by the second power monitor unit that is disposed on the lower side of the bent portion, with respect to light incident from above the said bending portion L _forward Coupling light, leakage light power P ^λ1 _{PD2 obtained} by modulating the light of wavelength λ1 at the bending portion with the frequency f1 with the coupling loss of L _back with respect to the light incident from below the bending portion, wave A step of light of longer .lambda.2 to measure the power P ^.lambda.2 _PD2 modulated leakage light at the frequency f2,
Approximate calculation by the following formulas (9) to (11) is performed with the ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light having the wavelength λ1 and the light having the wavelength λ2 incident on the optical line as a determination value. And a step of determining the presence / absence of an optical filter by using ΔP ′ _PD1 .
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11) In the optical filter presence / absence confirmation device for the optical line for judging the presence / absence of the optical filter for blocking a specific wavelength at the lower end portion of the optical line composed of one upper optical line and a plurality of lower optical lines branched by the optical branching element,
The modulated light obtained by modulating the light of wavelength λ1 in the cutoff region of the optical filter from the upper end of the upper optical line with the frequency f1 and the modulated light obtained by modulating the light of wavelength λ2 in the transmission region with the frequency f2 are incident power P ^λ1. _input , a light incident means for entering at a power of P ^λ2 _input ;
Arranged on the upper side of the bent portion provided in the lower optical line to be judged, L _forward coupling loss with respect to light incident from below the bent portion, and L _back against light incident from above the bent portion. The leakage light power P ^λ1 _{PD1 obtained} by modulating the light having the wavelength λ1 at the frequency f1 and the light P ^λ2 _PD1 obtained by modulating the light having the wavelength λ2 at the frequency f2 with the coupling loss of a first Pawamoni data means to measure,
It is arranged below the bent part, and has a coupling loss of L _forward with respect to light incident from above the bent part, and a coupling loss of L _back with respect to light incident from below the bent part. Te, a second Pawamoni measuring the power P ^.lambda.2 _PD2 light modulated leakage light at the frequency f2 of the optical frequency f1 power P of the modulated leakage light at ^.lambda.1 _PD2 and the wavelength .lambda.2 wavelength .lambda.1 at the bending portion and other hand stage,
Approximate calculation by the following formulas (9) to (11) is performed with the ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light having the wavelength λ1 and the light having the wavelength λ2 incident on the optical line as a determination value. Means for determining the presence or absence of an optical filter by using ΔP ′ _PD1 .
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ ((P λ2 PD1 - (P λ2 PD2 ÷ ΔL)) × ΔP LD) (9)
ΔL = P ^λ2 _PD2 ÷ P ^λ2 _PD1 (10)
ΔP _LD = P ^λ1 _input ÷ P ^λ2 _input (11) The ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light of wavelength λ1 and the light of wavelength λ2 to the optical line is approximately calculated by the following equation (11 ′), and the power ratio ΔP _LD is calculated. 4. The method of confirming the presence or absence of an optical filter in an optical line according to claim 1 or 3, wherein the approximate calculation is performed using equations (9) to (10).
ΔP _LD = P ^λ1 _PD2 ÷ P ^λ2 _PD2 (11 ′) The ratio ΔP _LD of the powers P ^λ1 _input and P ^λ2 _input of the light of wavelength λ1 and the light of wavelength λ2 to the optical line is approximately calculated by the following equation (11 ′), and the power ratio ΔP _LD is calculated. 5. The optical filter presence / absence confirmation apparatus for an optical line according to claim 2 or 4, wherein the approximate calculation is performed using equations (9) to (10).
ΔP _LD = P ^λ1 _PD2 ÷ P ^λ2 _PD2 (11 ′) 4. The method of confirming the presence or absence of an optical filter in an optical line according to claim 1 or 3, wherein the judgment value [Delta] P ' _PD1 is approximately calculated by the following equation (9').
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ (P λ2 PD1 × ΔP LD × α) (9')
Where α is a constant 5. The optical filter presence / absence confirmation device for an optical line according to claim 2, wherein the determination value ΔP ′ _PD1 is approximately calculated by the following equation (9 ′).
_{^{ΔP 'PD1 = (P λ1 PD1}} - (P λ2 PD2 ÷ ΔL × ΔP LD)) ÷ (P λ2 PD1 × ΔP LD × α) (9')
Where α is a constant

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