Estimation method, measurement method, and information processing device

Abstract

The present invention realizes an estimation method for estimating variation in measurement of group delay in an optical fiber. The estimation method (S1) includes an estimation step (S13) for estimating variation in measurement of group delay when light generated by a light source is inputted into an optical fiber, the estimation being made from the loss of the optical fiber and / or the power of the light source, using a relationship defined in advance.

Description

[Technical field]

[0001] The present invention relates to an estimation method for estimating measurement variation of group delay of an optical fiber, and to a measurement method for measuring a physical quantity representing an optical characteristic of an optical fiber using such an estimation method, and also to an information processing device for implementing such an estimation method or such a measurement method. [Background technology]

[0002] A representative physical quantity that represents the optical properties of an optical fiber is chromatic dispersion, which can be measured, for example, by a phase shift method.

[0003] The phase shift method includes a measurement step, a regression step, and a calculation step. The measurement step is a step of measuring group delays τ1, τ2, ..., τn at wavelengths λ1, λ2, ..., λn. The regression step is a step of determining a regression equation τ=τ(λ), in which the wavelength λ is an explanatory variable and the group delay τ when light of wavelength λ is input to an optical fiber is an objective variable, by referring to the group delays τ1, τ2, ..., τn at λ1, λ2, ..., λn obtained in the measurement step, by the least squares method. An example of the regression equation τ=τ(λ) is the Sellmeier equation τ=A+Bλ 2 +Cλ -2 The calculation step is a step of calculating the chromatic dispersion D(λ) using the regression equation τ=τ(λ) obtained in the regression step. The chromatic dispersion D(λ) is defined as D(λ)=dτ / dλ, so that D(λ)=2Bλ-2Cλ is obtained from the coefficients B and C of the Sellmeier formula. -3 It can be calculated according to:

[0004] In the calculation process, physical quantities other than the chromatic dispersion D(λ) can also be calculated. For example, the zero-dispersion wavelength λ0 defined as the solution of D(λ0)=0 can be calculated from the coefficients B and C of the Sellmeier formula as follows: λ0=(C / B) 1 / 4In addition, the zero dispersion slope slope@λ0 can be calculated from the coefficient B of the Sellmeier formula according to slope@λ0=8B, since slope@λ0=dD / dλ(λ0). Patent Document 1, for example, is an example of a document that discloses a method for measuring chromatic dispersion, zero-dispersion wavelength, and chromatic dispersion slope using the Sellmeier formula. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-236078 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as the optical fiber becomes longer, the measurement variation of the group delay increases due to noise. This reduces the accuracy of the regression equation obtained in the regression process, and as a result, reduces the accuracy of the physical quantity obtained in the calculation process. As an example, in the case of IEC Type B1 single mode fiber, such a problem occurs when the total length is longer than 156 km.

[0007] FIG. 9(a) is a graph plotting group delay (normalized relative group delay) at each wavelength obtained by daily measurement. FIG. 9(b) is a graph plotting the difference of group delay at each wavelength obtained by daily measurement from the average value at that wavelength. FIG. 9 shows a tendency that the measurement variation of group delay is large at both ends of the illustrated wavelength band and small at the center of the illustrated wavelength band. It is clear that such a tendency reduces the accuracy of the regression equation obtained in the regression process.

[0008] In order to improve the accuracy of the regression equation, it is effective to determine the regression equation by a weighted least squares method using weights according to the measurement variation of the group delay at each wavelength. However, there is no known method for theoretically specifying the measurement variation of the group delay. In addition, in order to experimentally specify the measurement variation of the group delay, it is necessary to repeatedly measure the group delay, which is time-consuming and laborious. For this reason, it is not realistic to experimentally specify the measurement variation of the group delay every time the optical fiber to be measured is changed.

[0009] One aspect of the present invention has been made in consideration of the above problems, and its purpose is to provide (1) an estimation method for estimating measurement variability of group delay of an optical fiber, (2) a measurement method for measuring a physical quantity representing an optical characteristic of an optical fiber using such an estimation method, (3) an information processing device for implementing such an estimation method, or (4) an information processing device for implementing such a measurement method. [Means for solving the problem]

[0010] The estimation method according to aspect 1 of the present invention includes an estimation step of estimating a measurement variation in group delay when light generated by a light source is input to an optical fiber from one or both of a loss in the optical fiber and a power of the light source by using a predetermined relational expression.

[0011] Furthermore, the measurement method according to aspect 5 of the present invention includes an estimation step of estimating the measurement variation of the group delay when light generated by a light source is input to an optical fiber from the wavelength of the light by using a relational equation according to the fiber length of the optical fiber. Effect of the Invention

[0012] According to one aspect of the present invention, it is possible to realize an estimation method for estimating measurement variation of group delay of an optical fiber. Also, according to another aspect of the present invention, it is possible to realize a measurement method for measuring a physical quantity representing an optical characteristic of an optical fiber by using such an estimation method. Also, according to another aspect of the present invention, it is possible to realize an information processing device for implementing such an estimation method. Also, according to another aspect of the present invention, it is possible to realize an information processing device for implementing such a measurement method. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a flow diagram showing the flow of an estimation method according to an embodiment of the present invention. [Diagram 2] 2 is a flow chart showing a specific example of a preparation step included in the estimation method shown in FIG. 1. [Diagram 3] 3 is a graph showing an example of power obtained in a first measurement step included in the preparation step shown in FIG. 2. [Figure 4] 3 is a graph showing an example of a loss obtained in a first measurement step included in the preparation step shown in FIG. 2. [Diagram 5] 3 is a graph showing an example of measurement variability of group delay obtained in a second measurement step included in the preparation step shown in FIG. 2. [Figure 6] 3 is a graph plotting a pair of the measurement variability (actual value) of group delay obtained in the second measurement step included in the preparation step shown in FIG. 2 and the measurement variability (estimated value) of group delay obtained by the regression equation obtained in the regression step shown in FIG. 2. [Figure 7] FIG. 1 is a flow chart showing the flow of a measurement method according to an embodiment of the present invention. [Figure 8] 1 is a block diagram showing a configuration of an information processing device according to an embodiment of the present invention; [Figure 9] (a) is a graph plotting the group delay (normalized relative group delay) at each wavelength obtained by daily measurements, and (b) is a graph plotting the difference of the group delay at each wavelength obtained by daily measurements from the average value at that wavelength. [Figure 10] 1 is a graph showing an example of the standard deviation of group delay. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Flow of estimation method) The flow of the estimation method S1 according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a flow diagram showing the flow of the estimation method S1.

[0015] As shown in FIG. 1, the estimation method S1 includes a preparation step S11, a measurement step S12, and an estimation step S13.

[0016] The preparation step S11 is a step of preparing a relational expression Δ=Δ(L,P) for deriving a measurement variation Δ of a group delay τ when light generated by a light source is input to the optical fiber from the loss L of the optical fiber and the power P of the light source. A specific example of the preparation step S11 will be described later with reference to a different drawing. The group delay may be an absolute group delay or a relative group delay, but in this embodiment, a relative group delay is used. Moreover, the measurement variation may be a standard deviation of the measurement value or a variance of the measurement value, but in this embodiment, a standard deviation is used.

[0017] The measurement step S12 is a step of measuring the loss L of an optical fiber (hereinafter, referred to as the "optical fiber OF") whose optical characteristics are to be measured. OF , and the power P of the light source (hereinafter referred to as "light source LS") used to measure the optical characteristics. LS This is the process of measuring the loss L OF Although the measurement method of is arbitrary, in this embodiment, the OTDR method is used. Instead of the OTDR method, the cutback method is used to measure the loss L OF The loss value per unit length obtained by the OTDR method or the cutback method is multiplied by the length of the optical fiber OF to obtain the loss L OF The power PLS can be measured by any method. When the estimation method S1 is performed using an information processing device 1 described later, the information processing device 1 can obtain the loss L OF and Power PLS In this acquisition step, the information processing device 1 acquires the loss L input by the user using an input device connected to the information processing device 1. OF and Power P LS Alternatively, the loss L may be acquired by communication from a measuring device connected to the information processing device 1. OF and Power P LS may be obtained.

[0018] In the estimation step S13, the measurement variation Δ OF,LS The loss L obtained in the measurement step S12 OF and Power P LS In this step, the loss L is estimated using the relational expression Δ=Δ(L, P) obtained in the preparation step S11. OF and Power P LS By substituting the above into the relation Δ=Δ(L,P), the measurement variation of the group delay Δ OF,LS =Δ(L OF ,P LS ) is obtained.

[0019] If the relational expression Δ=Δ(L,P) is prepared in advance, the preparation step S11 can be omitted. For example, when the estimation method S1 is performed on a plurality of optical fibers having similar optical characteristics, the preparation step S11 can be omitted in the estimation method S1 for the second and subsequent optical fibers. This is because the relational expression Δ=Δ(L,P) obtained in the preparation step S11 for the first optical fiber can be used in the estimation method S1 for the second and subsequent optical fibers. formula Loss L to be substituted into Δ=Δ(L,P) OF If is in the domain of the relational expression Δ=Δ(L,P) (range of loss L), it is necessary to expand the domain of the relational expression Δ=Δ(L,P) by extrapolation, which may result in a decrease in the estimation accuracy. In order to avoid such a decrease in the estimation accuracy, OFIt is preferable to create the relational expression Δ=Δ(L,P) by referring to a sufficiently wide range of losses L so that the loss L is included in the domain of the relational expression Δ=Δ(L,P). Alternatively, a plurality of relational expressions Δ=Δ(L,P) with different domains are created in advance, and the losses L of the second and subsequent optical fibers are calculated. OF A relational expression Δ=Δ(L,P) including the above in its domain may be selected and used. Here, the optical fiber loss L per unit length of the optical fiber at each wavelength may be uniform within the range of manufacturing error, or it may not be uniform. Furthermore, the optical fiber loss L may be uniform within the range of manufacturing error in the preparation step S11 and the measurement step S12, or it may not be uniform. Furthermore, the light source power P at each wavelength may be uniform within the range of manufacturing error, or it may not be uniform. Furthermore, the light source power P may be uniform within the range of manufacturing error in the preparation step S11 and the measurement step S12, or it may not be uniform. At least one of the optical fiber loss L and the light source power P is not uniform.

[0020] The estimation method S1 may be performed only when the fiber length of the optical fiber is within a predetermined range. For example, if the measurement variation of the group delay is not a problem when the fiber length of the optical fiber is less than a predetermined length (e.g., 156 km), the estimation method S1 may be performed only when the fiber length of the optical fiber is equal to or greater than the predetermined length. Alternatively, if the measurement variation of the group delay is not a problem when the fiber length of the optical fiber is less than a predetermined first length (e.g., 156 km), and the validity of the relational expression Δ=Δ(L, P) is lost when the fiber length of the optical fiber is longer than a predetermined second length (e.g., 180 km), the estimation method S1 may be performed only when the fiber length of the optical fiber is equal to or greater than the first length and equal to or less than the second length.

[0021] (Example of preparation process) A specific example of the preparation step S11 included in the estimation method S1 will be described with reference to Fig. 2. Fig. 2 is a flow diagram showing a specific example of the preparation step S11. The preparation step S11 is performed using an optical fiber (hereinafter referred to as "optical fiber OF'") that is the same as or the same type as the optical fiber OF, and a light source (hereinafter referred to as "light source LS'") that is the same as or the same type as the light source LS.

[0022] In the preparation step S11, a regression equation is obtained in which the optical fiber loss L and the power P of the light source are set as objective variables for the above-mentioned relational equation Δ=Δ(L,P), and the measurement variation Δ of the group delay τ when the light generated by the light source is input to the optical fiber is set as an explanatory variable. For this reason, in this section, the above-mentioned relational equation Δ=Δ(L,P) is also referred to as the regression equation Δ=Δ(L,P).

[0023] As shown in FIG. 2, the preparation step S11 includes a first measurement step S111, a second measurement step S112, and a regression step S113.

[0024] The first measurement step S111 is a step of measuring the loss Li of the optical fiber OF' at each of the plurality of different wavelengths λ1, λ2, ..., λn, and the power Pi of the light source LS' at each of the plurality of wavelengths λ1, λ2, ..., λn. Here, n is any natural number equal to or greater than 2. Also, i is any natural number equal to or greater than 1 and equal to or less than n. The loss Li represents the loss of the optical fiber OF' at the wavelength λi, and the power Pi represents the power of the light source LS' at the wavelength λi. LS'The power of the loss Li is represented by the power P1, P2, ..., Pn. The method of measuring the losses L1, L2, ..., Ln is arbitrary, but in this embodiment, the OTDR method is used. Instead of the OTDR method, the losses L1, L2, ..., Ln may be measured using a cutback method. The method of measuring the power P1, P2, ..., Pn is arbitrary. When the estimation method S1 is implemented using an information processing device 1 described later, the information processing device 1 executes a first acquisition step of acquiring the loss Li and the power Pi. In this first acquisition step, the information processing device 1 may acquire the loss Li and the power Pi input by a user using an input device connected to the information processing device 1, or may acquire the loss Li and the power Pi from a measurement device connected to the information processing device 1 by communication.

[0025] The second measurement step S112 is a step of repeatedly measuring the group delay τi when the light generated by the light source LS' is input to the optical fiber OF' for each of the plurality of wavelengths λ1, λ2, ..., λn, and calculating the measurement variation Δi of the group delay τi from the obtained plurality of measured values. Here, the group delay τi represents the group delay of the optical fiber OF' at the wavelength λi. Although any method for measuring the group delay τi may be used, the phase shift method is used in this embodiment. Note that, when the estimation method S1 is implemented using an information processing device 1 described later, the information processing device 1 executes a second acquisition step of acquiring the group delay τi. In this second acquisition step, the information processing device 1 may acquire the group delay τi input by a user using an input device connected to the information processing device 1, or may acquire the group delay τi from a measurement device connected to the information processing device 1 by communication.

[0026] The regression step S113 is a step of determining a regression equation Δ=Δ(L,P) with the optical fiber loss L and the light source power P as explanatory variables and the measurement variation Δ of the group delay τ when the light generated by the light source is input to the optical fiber as a response variable, by referring to the losses L1, L2, ..., Ln and powers P1, P2, ..., Pn obtained in the first measurement step S111 and the measurement variations Δ1, Δ2, ..., Δn obtained in the second measurement step S112. The least square method is used to determine the regression equation Δ=Δ(L,P). That is, Σ{Δ(Li,Pi)-Δi}2 The coefficients included in the regression equation Δ=Δ(P,L) are determined so as to minimize the above. Here, Σ represents the sum over i=1, 2, ..., n. The regression equation Δ=Δ(P,L) is not particularly limited, but in this embodiment, log(Δ)=αP+βL+γ, that is, Δ=exp(αP+βL+γ), is used as the regression equation Δ=Δ(P,L).

[0027] (Example of preparation process) An example of the preparation step S11 shown in FIG. 2 will be described with reference to FIGS.

[0028] figure 4 1 is a graph showing an example of the loss Li (the total loss obtained by measuring the loss per unit length and multiplying the loss by the fiber length) obtained in the first measurement step S111. 3 FIG. 5 is a graph showing an example of the measurement variation Δi of the group delay τi obtained in the second measurement step S112. Note that, among the losses Li shown in FIG. 3, a part is an actual measurement value, and the remaining part is a loss model. To The sweep value is based on

[0029] figure 4 The losses L1, L2, …, Ln shown in Fig. 3 , Pn shown in FIG. 5 and the measurement variations Δ1, Δ2, ..., Δn of the group delay τi shown in FIG. 5 were used to perform the regression step S113, and the coefficients of the regression equation log(Δ)=αP+βL+γ were determined as follows.

[0030] α=-2.39, β=0.0865 0 , γ=-5.67.

[0031] 6 is a graph plotting a pair of the measurement variation Δi (actual value) of the group delay τi obtained in the second measurement step S112 and the measurement variation Δ(Li,Pi) (estimated value) of the group delay τi obtained by the regression equation log(Δ)=αP+βL+γ. From FIG. 6, it can be seen that each plot is distributed near the diagonal line (dotted line). This means that the estimated value closely approximates the actual measurement value.

[0032] (Measurement method flow) The flow of the measurement method S2 according to one embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a flow diagram showing the flow of the measurement method S2.

[0033] As shown in FIG. 7, the measurement method S2 includes a measurement step S21, an estimation step S22, a regression step S23, and a calculation step S24.

[0034] The measurement step S21 is a step of measuring a group delay τj when light generated by the light source LS is input to the optical fiber OF for each of a plurality of different wavelengths λ1, λ2, ..., λm. Here, m is any natural number equal to or greater than 2. The group delay τj represents the group delay of the optical fiber OF at the wavelength λj (j=1, 2, ..., m). Any method for measuring the group delay τj is available, but in this embodiment, a phase shift method is used. When the measurement method S2 is performed using an information processing device 1 described later, the information processing device 1 executes an acquisition step of acquiring the group delay τj. In this acquisition step, the information processing device 1 may acquire the group delay τj input by a user using an input device connected to the information processing device 1, or may acquire the group delay τj from a measurement device connected to the information processing device 1 by communication.

[0035] The estimation step S22 is a step of estimating a measurement variation Δj of a group delay τj when light generated by a light source LS is input to an optical fiber OF for each of the plurality of wavelengths λ1, λ2, ..., λm. The estimation step S22 is performed by carrying out the above-mentioned estimation method S1 for each of the plurality of wavelengths λ1, λ2, ..., λm.

[0036] The regression step S23 is a step of determining a regression equation τ=τ(λ) with the wavelength λ as an explanatory variable and the group delay τ when the light of the wavelength λ is input to the optical fiber as a response variable, by referring to the group delays τ1, τ2, ..., τm obtained in the measurement step S21. The regression equation τ=τ(λ) is determined by the least squares method using weights wj according to the measurement variance Δj estimated in the estimation step S22. That is, Σwj{τ(λj)-τj} 2 The coefficients included in the regression equation τ=τ(λ) are determined so as to minimize the above. Here, Σ represents the sum over j=1, 2, ..., m. The regression equation τ=τ(λ) is not particularly limited, but in this embodiment, the three-term Sellmeier equation τ=A+Bλ 2 +Cλ -2 is used as the regression equation τ = τ(λ). The 5-term Sellmeier equation τ = A + Bλ 2 +Cλ -2 +Dλ 4 +Eλ -4 may be used as the regression equation τ = τ(λ). Also, a quadratic polynomial, a cubic polynomial, or a quartic polynomial may be used as the regression equation τ = τ(λ). As the measurement variation Δj, the standard deviation σj or the variance σj 2 When using, for example, the weight wj is 1 / σj 2 can be used.

[0037] The calculation step S24 is a step of calculating a physical quantity representing the optical characteristic of the optical fiber OF using the regression equation τ=τ(λ) obtained in the regression step S23. For example, when the chromatic dispersion D(λ) of the optical fiber OF is to be measured, D(λ)=2Bλ-2Cλ is calculated from the coefficients B and C of the three-term Sellmeier equation. -3 Calculate the chromatic dispersion D(λ) according to the formula below. Alternatively, to calculate the zero dispersion wavelength λ0 of the optical fiber OF, use the coefficients B and C of the three-term Sellmeier formula to get λ0=(C / B) 1 / 4Alternatively, when the zero dispersion slope slope@λ0 of the optical fiber OF is to be measured, the zero dispersion slope slope@λ0 is calculated from the coefficient B of the three-term Sellmeier equation according to slope@λ0=8B. When the five-term Sellmeier equation is used as the regression equation τ=τ(λ), the coefficients B, C, D, and E are used to calculate D(λ)=2Bλ-2Cλ -3 +4Dλ 3 -4Eλ -5 The chromatic dispersion D(λ) can be calculated according to the following:

[0038] (Configuration of information processing device) The configuration of an information processing device 1 according to an embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a block diagram showing the configuration of the information processing device 1.

[0039] The information processing device 1 is realized using a general-purpose computer, and includes a processor 11, a primary memory 12, a secondary memory 13, an input / output interface 14, a communication interface 15, and a bus 16. The processor 11, the primary memory 12, the secondary memory 13, the input / output interface 14, and the communication interface 15 are connected to each other via the bus 16.

[0040] The secondary memory 13 stores an estimation program P1 and a measurement program P2. The processor 11 loads the estimation program P1 stored in the secondary memory 13 onto the primary memory 12. The processor 11 then executes each step included in the estimation method S1 according to the instructions included in the estimation program P1 loaded onto the primary memory 12. The processor 11 also loads the measurement program P2 stored in the secondary memory 13 onto the primary memory 12. The processor 11 then executes each step included in the measurement method S2 according to the instructions included in the measurement program P2 loaded onto the primary memory 12. Note that in each measurement step included in the estimation method S1 and the measurement method S2, the processor 11 does not perform the measurement itself, but performs a process of acquiring a measured value from a measurement device or an input device.

[0041] Examples of devices that can be used as the processor 11 include a central processing unit (CPU), a graphic processing unit (GPU), a digital signal processor (DSP), a micro processing unit (MPU), a floating point number processing unit (FPU), a physics processing unit (PPU), a microcontroller, or a combination of these. The processor 11 is also called a "computing device."

[0042] Moreover, a device that can be used as the primary memory 12 can be, for example, a RAM (Random Access Memory). The primary memory 12 is sometimes called a "main storage device". Moreover, a device that can be used as the secondary memory 13 can be, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), an optical disk drive (ODD), or a combination thereof. The secondary memory 13 is sometimes called an "auxiliary storage device". The secondary memory 13 may be built in the information processing device 1, or may be built in another computer (for example, a computer constituting a cloud server) connected to the information processing device 1 via the input / output interface 14 or the communication interface 15. In this embodiment, the storage in the information processing device 1 is realized by two memories (the primary memory 12 and the secondary memory 13), but is not limited to this. That is, the storage in the information processing device 1 may be realized by one memory. In this case, for example, a certain storage area of ​​the memory may be used as the primary memory 12, and another storage area of ​​the memory may be used as the secondary memory 13.

[0043] An input device and / or an output device are connected to the input / output interface 14. Examples of the input / output interface 14 include interfaces such as Universal Serial Bus (USB), Advanced Technology Attachment (ATA), Small Computer System Interface (SCSI), and Peripheral Component Interconnect (PCI). Examples of input devices connected to the input / output interface 14 include various measuring devices. When automatically inputting measured values ​​measured in each measurement step included in the estimation method S1 and the measurement method S2, the processor 11 acquires these measured values ​​from the measuring device via the input / output interface 14 and stores them in the primary memory 12. Examples of input devices connected to the input / output interface 14 include a keyboard, a mouse, a touchpad, a microphone, or a combination of these. When manually inputting measured values ​​measured in each measurement step included in the estimation method S1 and the measurement method S2, the processor 11 acquires these measured values ​​from the input device via the input / output interface 14 and stores them in the primary memory 12. Examples of output devices connected to the input / output interface 14 include a display, a projector, a printer, a speaker, a headphone, or a combination of these. Information (such as an estimation result or a measurement result) provided to the user in the estimation method S1 and the measurement method S2 is output from the information processing device 1 via these output devices. The information processing device 1 may incorporate a keyboard that functions as an input device and a display that functions as an output device, like a laptop computer. Alternatively, the information processing device 1 may incorporate a touch panel that functions as both an input device and an output device, like a tablet computer.

[0044] The communication interface 15 is connected to other computers via a network in a wired or wireless manner. Examples of the communication interface 15 include interfaces such as Ethernet (registered trademark) and Wi-Fi (registered trademark). Examples of available networks include a personal area network (PAN), a local area network (LAN), a campus area network (CAN), a metropolitan area network (MAN), a wide area network (WAN), a global area network (GAN), or an internetwork including these networks. The internetwork may be an intranet, an extranet, or the Internet. Data acquired by the information processing device 1 from other computers in the estimation method S1 and the measurement method S2, and data provided by the information processing device 1 to other computers in the estimation method S1 are transmitted and received via these networks.

[0045] In this embodiment, a configuration in which the estimation method S1 is executed using a single processor (processor 11) is adopted, but the present invention is not limited to this. That is, a configuration in which the estimation method S1 is executed using multiple processors may be adopted. In this case, the multiple processors that execute the estimation method S1 in cooperation with each other may be provided in a single computer and configured to be able to communicate with each other via a bus, or may be provided in a distributed manner in multiple computers and configured to be able to communicate with each other via a network. As an example, a processor built in a computer that constitutes a cloud server and a processor built in a computer owned by a user of the cloud server may cooperate to execute the estimation method S1. The same can be said about the measurement method S2.

[0046] In addition, in this embodiment, a configuration is adopted in which the estimation program P1 is stored in a memory (secondary memory 13) built into the same computer as the processor (processor 11) that executes the estimation method S1, but the present invention is not limited to this. That is, a configuration may be adopted in which the estimation program P1 is stored in a memory built into a computer different from the processor that executes the estimation method S1. In this case, the computer built into the memory that stores the estimation program P1 is configured to be able to communicate with the computer built into the processor that executes the estimation method S1 via a network. As an example, a mode is considered in which the estimation program P1 is stored in a memory built into a computer that constitutes a cloud server, and a processor built into a computer owned by a user of the cloud server executes the estimation method S1. The same can be said about the measurement method S2 and the measurement program P2.

[0047] (Support for optical fibers of different fiber lengths)

[0048] According to an experiment conducted by the inventors of the present application, the wavelength dependency of the measurement variability of group delay (group delay standard deviation) differs depending on the fiber length of the optical fiber. Fig. 10 is a graph showing the experimental results. Here, the wavelength dependency of the measurement variability of group delay is shown for optical fiber A and optical fiber B (represented as fiber:B in Fig. 10) which is longer than optical fiber A (represented as fiber:A in Fig. 10). This suggests that it is preferable to use different relational expressions Δ=Δ(L,P) used in estimation method S1 for different fiber lengths.

[0049] More specifically, in the estimation method S1, it is preferable to execute the preparation step S11 including the first measurement step S111, the second measurement step S112, and the regression step S113 for a plurality of optical fibers having different fiber lengths. In addition, in the estimation step S13 of the estimation method S1, among the regression equations for each of the plurality of optical fibers obtained in the regression step S113, the one having the fiber length closest to the fiber length of the optical fiber to be estimated or the one having the loss closest to the fiber length of the optical fiber to be estimated is selected. lossIt is preferable to use the regression equation for the optical fiber closest to . This makes it possible to estimate the group delay variation with higher accuracy. loss Even when using a regression equation for an optical fiber whose fiber length is closest to the fiber length of the optical fiber to be estimated, the same results can be obtained as when using a regression equation for an optical fiber whose fiber length is closest to the fiber length of the optical fiber to be estimated, because there is a positive correlation between the fiber length and the loss.

[0050] (Modification) When the power of the light source at each wavelength is uniform within the range of manufacturing error, and the loss per unit length of the optical fiber at each wavelength is uniform within the range of manufacturing error, the wavelength dependency of the measurement variation of the group delay is determined by the fiber length FL of the optical fiber. In this case, the preparation step S11 of the above-mentioned estimation method S1 can be changed to a preparation step S11 including the following measurement step and regression step. Here, the power of the light source at each wavelength is uniform within the range of manufacturing error in the preparation step S11 and the measurement step S12. Also, the loss per unit length of the optical fiber at each wavelength is uniform within the range of manufacturing error in the preparation step S11 and the measurement step S12.

[0051] The measurement step is a step of repeatedly measuring the group delay τji when light of wavelength λi (i is a natural number between 1 and n) is input to an optical fiber of fiber length FLj (j is a natural number between 1 and m) for each of a plurality of fiber lengths FL1, FL2, ..., FLm and each of a plurality of wavelengths λ1, λ2, ..., λn, and calculating the measurement variation Δji of the group delay τji from the obtained plurality of measured values. Note that, when the estimation method S1 according to this modification is implemented using the above-mentioned information processing device 1, the information processing device 1 executes an acquisition step of acquiring the group delay τji. In this acquisition step, the information processing device 1 may acquire the group delay τji input by a user using an input device connected to the information processing device 1, or may acquire the group delay τji from a measurement device connected to the information processing device 1 by communication.

[0052] The regression process is a process of determining a regression equation Δj=Δj(λ) for each of a plurality of fiber lengths FL1, FL2, ..., FLm, with the wavelength λ as the explanatory variable and the measurement variation Δj of the group delay when light of the wavelength λ is input to an optical fiber of fiber length FLj as the objective variable, by referring to the measurement variations Δj1, Δj2, ..., Δjn obtained in the measurement process (acquisition process). The least squares method is used to determine the regression equation Δj=Δj(λ). That is, Σ{Δj(λi)-Δji} 2 The coefficients included in the regression equation Δj=Δj(λ) are determined so as to minimize the above. Here, Σ represents the sum over i=1, 2, ..., n. The regression equation Δj=Δj(λ) is not particularly limited, but in this modified example, Δj=α j ×exp(β j × λ) is used as the regression equation Δj = Δj(λ).

[0053] In this case, in the measurement step S12 of the estimation method S1, the fiber length FL of the optical fiber OF to be subjected to the optical characteristic measurement is OF When the estimation method S1 is carried out using the above-described information processing device 1, the information processing device 1 measures the fiber length FL OF In this acquisition step, the information processing device 1 executes an acquisition step of acquiring the fiber length FL input by the user using an input device connected to the information processing device 1. OF Alternatively, the fiber length FL may be acquired by communication from a measuring device connected to the information processing device 1. OF may be obtained.

[0054] In this case, in the estimation step S13 of the estimation method S1, the wavelength λ The measurement variation Δ of group delay τ when 0 light is input to the optical fiber OF λ0,OF is the fiber length FL obtained in the measurement step S12. OF From the relation Δ obtained in the preparation step S11 OF = Δ OF (λ) is used to estimate the wavelength. λ 0, the relation Δ OF = Δ OF By substituting for (λ), the measurement variation of group delay, Δ OF = ΔOF ( λ 0), where the relation Δ OF = Δ OF (λ) is the fiber length FL obtained in the measurement step S12 among the multiple regression equations Δ1=Δ1(λ), ​​Δ2=Δ2(λ), ..., Δm=Δm(λ) obtained in the preparation step described above. OF For example, the regression equation for the fiber length FL OF If the fiber length closest to is FL1, then the relationship Δ OF = Δ OF (λ) is Δ1=Δ1(λ) and the fiber length FL OF If the fiber length closest to is FL2, then the relationship Δ OF = Δ OF (λ) is Δ2 = Δ2(λ).

[0055] (Summary 1) The estimation method according to aspect 1 of the present invention includes an estimation step of estimating a measurement variation in group delay when light generated by a light source is input to an optical fiber from one or both of a loss in the optical fiber and a power of the light source by using a predetermined relational expression.

[0056] The estimation method according to the first aspect of the present invention may further include an acquisition step of acquiring one or both of the loss of the optical fiber and the power of the light source. In this case, the estimation step may be a step of estimating the measurement variation of the group delay from one or both of the loss and the power acquired in the acquisition step.

[0057] In the estimation method according to aspect 2 of the present invention, in addition to the configuration of aspect 1, the estimation step is a step of estimating the measurement variation from one or both of the loss and the power by using a relational equation corresponding to the fiber length of the optical fiber from among a plurality of predetermined relational equations.

[0058] An estimation method according to a third aspect of the present invention includes, in addition to the configuration of the first aspect, a first acquisition step of acquiring one or both of an optical fiber loss at each of a plurality of different wavelengths and a light source power at each of the plurality of wavelengths; a second acquisition step of acquiring a plurality of measurement values ​​obtained by repeatedly measuring a group delay when light generated by the light source is input into the optical fiber for each of the plurality of wavelengths, and calculating a measurement variation of the group delay from the plurality of measurement values; and a regression step of deriving a regression equation Δ=Δ(L,P) having one or both of the optical fiber loss L and the light source power P as explanatory variables and a measurement variation Δ of the group delay when light generated by the light source is input into the optical fiber as a response variable, by a least squares method with reference to one or both of the loss and power acquired in the first acquisition step and the measurement variation acquired in the second acquisition step, and the relational equation used in the estimation step is the regression equation acquired in the regression step.

[0059] An estimation method according to a fourth aspect of the present invention includes, in addition to the configuration of the second aspect, a first acquisition step of acquiring one or both of an optical fiber loss at each of a plurality of different wavelengths and a light source power at each of the plurality of wavelengths; a second acquisition step of acquiring a plurality of measurement values ​​obtained by repeatedly measuring a group delay when light generated by the light source is input to the optical fiber for each of the plurality of wavelengths, and calculating a measurement variance of the group delay from the plurality of measurement values; and a third acquisition step of calculating a measurement variance of the group delay when light generated by the light source is input to the optical fiber from the plurality of measurement values, using one or both of the optical fiber loss L and the light source power P as explanatory variables. a regression process in which a regression equation Δ=Δ(L,P) with Δ as a target variable is derived by a least squares method with reference to one or both of the loss and power obtained in the first acquisition process and the measurement variation obtained in the second acquisition process, and the above-mentioned multiple relational equations are regression equations for each of the multiple optical fibers obtained in the regression process, and the relational equation used in the estimation process is the regression equation for the optical fiber of which fiber length is closest to the fiber length of the optical fiber or whose loss is closest to the loss of the optical fiber, among the multiple relational equations.

[0060] A measurement method according to a fifth aspect of the present invention includes an estimation step of estimating the measurement variation of group delay when light generated by a light source is input into an optical fiber from the wavelength of the light using a relational equation according to the fiber length of the optical fiber.

[0061] A measurement method according to a sixth aspect of the present invention includes, in addition to the configuration of the fifth aspect, a step of: measuring a wavelength λi (i is a natural number that is 1 or more and is equal to or less than n) of light at each of a plurality of fiber lengths FL1, FL2, ..., FLm and a plurality of wavelengths λ1, λ2, ..., λn, by measuring a wavelength λi (i is a natural number that is 1 or more and is equal to or less than n) of light at each of a plurality of fiber lengths FLj (j is a natural number that is 1 or more and is equal to or less than m). Optical fiber ) to obtain multiple measured values ​​obtained by repeatedly measuring the group delay τji when the i and calculating a regression equation Δj=Δj(λ) for each of the plurality of fiber lengths FL1, FL2, ..., FLm, in which the wavelength λ is an explanatory variable and the measurement variation Δj of the group delay when light of the wavelength λ is input to an optical fiber having a fiber length FLj is an objective variable, The above and a regression process of deriving the relational equation by a least squares method with reference to the measurement variations Δj1, Δj2, ..., Δjn obtained in the acquisition process, wherein the relational equation used in the estimation process is the regression equation corresponding to the fiber length closest to the fiber length of the optical fiber among the multiple regression equations Δ1=Δ1(λ), ​​Δ2=Δ2(λ), ..., Δm=Δm(λ) obtained in the regression process.

[0062] A measuring method according to a sixth aspect of the present invention is similar to any one of the first and fourth to sixth aspects, in that the estimation step is performed only when the fiber length of the optical fiber is within a predetermined range.

[0063] Aspects of the invention 7The measurement method according to the aspect includes an acquisition step of acquiring a group delay when light generated by a light source is input into an optical fiber for each of a plurality of different wavelengths; an estimation step of estimating, for each of a plurality of different wavelengths, a measurement variability of the group delay when the light generated by the light source is input into the optical fiber by using the estimation method according to any one of aspects 1 to 7; a regression step of determining a regression equation τ=τ(λ) in which the wavelength λ is an explanatory variable and the group delay τ when the light of the wavelength λ is input into the optical fiber is an objective variable by a weighted least squares method using a weight according to the measurement variability obtained in the estimation step, by referring to the group delay acquired in the acquisition step; and a calculation step of calculating a physical quantity representing an optical characteristic of the optical fiber by using the regression equation τ=τ(λ) acquired in the regression step.

[0064] A ninth aspect of the present invention relates to a measurement method according to the eighth aspect, in which the regression equation τ=τ(λ) is expressed by the Sellmeier equation τ=A+Bλ 2 +Cλ -2 It is.

[0065] A measurement method according to a tenth aspect of the present invention has the same configuration as in the ninth aspect, and further comprises: λ 0, or zero dispersion slope λ 0, and the calculation step calculates the chromatic dispersion D(λ) as follows: D(λ)=2Bλ- 2Cλ -3 Calculating the zero dispersion wavelength according to λ 0, λ 0= (C / B) 1 / 4 or a zero dispersion slope @ λ 0, slope@ λ 0=8B.

[0066] In addition, an information processing device for implementing the estimation method according to any one of aspects 1 to 7, and an information processing device for implementing the estimation method according to aspects 8 to 10 An information processing device for carrying out the measurement method according to any one of the above aspects is also included in the scope of the present invention.

[0067] (Summary 2) The estimation method according to a first aspect of the present invention includes a measurement step of measuring one or both of a loss of an optical fiber and a power of a light source, and an estimation step of estimating a measurement variability of a group delay when light generated by the light source is input to the optical fiber from one or both of the loss and the power obtained in the measurement step by using a predetermined relational expression.

[0068] According to the above method, it is possible to estimate the measurement variability of the group delay without repeatedly measuring the group delay.

[0069] The estimation method according to a second aspect of the present invention further includes, in addition to the configuration of the first aspect, a first measurement step of measuring one or both of a loss of an optical fiber at each of a plurality of different wavelengths and a power of a light source at each of the plurality of wavelengths; a second measurement step of repeatedly measuring, for each of the plurality of wavelengths, a group delay when light generated by the light source is input to the optical fiber and calculating a measurement variation of the group delay from the obtained plurality of measurement values; and a regression step of deriving a regression equation Δ=Δ(L,P) having one or both of the loss L of the optical fiber and the power P of the light source as explanatory variables and a measurement variation Δ of the group delay when light generated by the light source is input to the optical fiber as an objective variable, by a least squares method with reference to one or both of the loss and power obtained in the first measurement step and the measurement variation obtained in the second measurement step, wherein the relational equation is the regression equation Δ=Δ(L,P) obtained in the regression step.

[0070] According to the above method, the measurement variability of the group delay can be estimated using the regression equation Δ=Δ(L,P).

[0071] A measurement method according to a third aspect of the present invention includes a measurement step of measuring a group delay when light generated by a light source is input into an optical fiber for each of a plurality of different wavelengths; an estimation step of estimating, for each of a plurality of different wavelengths, a measurement variability of the group delay when the light generated by the light source is input into the optical fiber by using the estimation method according to the first or second aspect; a regression step of determining a regression equation τ=τ(λ) in which the wavelength λ is an explanatory variable and the group delay τ when the light of the wavelength λ is input into the optical fiber is an objective variable by a weighted least squares method using a weight according to the measurement variability obtained in the estimation step, with reference to the group delay obtained in the measurement step; and a calculation step of calculating a physical quantity representing an optical characteristic of the optical fiber by using the regression equation τ=τ(λ) obtained in the regression step.

[0072] According to the above method, the physical quantities that represent the optical characteristics of the optical fiber can be measured with high accuracy.

[0073] In a measurement method according to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the regression equation τ=τ(λ) is expressed by the Sellmeier equation τ=A+Bλ 2 +Cλ -2 The form adopted is as follows.

[0074] According to the above method, the regression equation τ=τ(λ) can be easily determined with high accuracy.

[0075] In a measurement method according to a fifth aspect of the present invention, in addition to the configuration of the fourth aspect, the physical quantity is a chromatic dispersion D(λ), a zero dispersion wavelength λ 0, or zero dispersion slope λ 0, and the calculation step calculates the chromatic dispersion D(λ) as follows: D(λ)=2Bλ- 2Cλ -3 Calculating the zero dispersion wavelength according to λ 0, λ 0= (C / B) 1 / 4 or a zero dispersion slope @ λ 0, slope@ λThe method adopted is to calculate according to 0=8B.

[0076] According to the above method, the chromatic dispersion D(λ) and zero dispersion wavelength of the optical fiber λ 0, or zero dispersion slope λ 0 can be measured with high accuracy.

[0077] In addition, an information processing device for implementing the estimation method according to the first or second aspect, and an information processing device for implementing the estimation method according to the third to fourth aspects 5 An information processing device for carrying out the measurement method according to any one of the above aspects is also included in the scope of the present invention.

[0078] (Additional Notes) The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. Other embodiments obtained by appropriately combining the technical means disclosed in the above-described embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0079] S1 estimation method S11 Preparation process S111 1st measurement process S112 2nd measurement process S113 Regression process S12 Measurement process S13 Estimation process S2 measurement method S21 Measurement process S22 Estimation process S23 Regression process S24 Calculation process 1. Information processing device 11 Processors 12 Primary Memory 13 Secondary Memory 14 Input / Output Interface 15 Communication Interface 16 Bus

Claims

1. The method includes an estimation step of estimating a measurement variation of a group delay when light generated by a light source is input to an optical fiber to be measured from one or both of a loss of the optical fiber and a power of the light source by using a predetermined relational expression, The relational expression is a regression equation Δ=Δ(L, P) in which one or both of the loss L of the optical fiber and the power P of the light source are explanatory variables, and the measurement variation Δ of the group delay when the light generated by the light source is input to the optical fiber is a response variable. The estimation method according to claim 1,

2. the estimation step is a step of estimating the measurement variation from one or both of the loss and the power by using a relational equation corresponding to a fiber length of the optical fiber to be measured, among a plurality of predetermined relational equations; The plurality of relational expressions are regression equations Δ=Δ(L, P) for each of a plurality of optical fibers having different fiber lengths, the regression equations Δ=Δ(L, P) having one or both of an optical fiber loss L and a light source power P as explanatory variables, and having a measurement variation Δ of a group delay when light generated by the light source is input to the optical fiber as a response variable; The relational equation used in the estimation step is a regression equation Δ=Δ(L, P) for an optical fiber whose fiber length is closest to the fiber length of the optical fiber to be measured or whose loss is closest to the loss of the optical fiber to be measured, among the plurality of relational equations.

2. The method according to claim 1 .

3. a first acquisition step of acquiring one or both of a loss of an optical fiber at each of a plurality of different wavelengths and a power of a light source at each of the plurality of wavelengths; a second acquisition step of acquiring a plurality of measured values ​​obtained by repeatedly measuring a group delay when light generated by the light source is input to the optical fiber for each of the plurality of wavelengths, and calculating a measurement variation of the group delay from the plurality of measured values; The method further includes a regression process of deriving the regression equation Δ=Δ(L, P) by a least squares method with reference to one or both of the loss and power obtained in the first acquisition process and the measurement variation obtained in the second acquisition process.

2. The method according to claim 1 .

4. a first acquisition step of acquiring one or both of a loss of an optical fiber at each of a plurality of different wavelengths and a power of a light source at each of the plurality of wavelengths; a second acquisition step of acquiring a plurality of measured values ​​obtained by repeatedly measuring a group delay when light generated by the light source is input to the optical fiber for each of the plurality of wavelengths, and calculating a measurement variation of the group delay from the plurality of measured values; a regression process of deriving the regression equation Δ=Δ(L, P) by a least squares method with reference to one or both of the loss and power obtained in the first acquisition process and the measurement variation obtained in the second acquisition process, and executing the regression process for each of a plurality of optical fibers having different fiber lengths. The method according to claim 2 .

5. The method includes an estimation step of estimating a measurement variation of a group delay when light generated by a light source is input to an optical fiber to be measured, from a wavelength of the light by using a relational expression according to a fiber length of the optical fiber, The relational expression is a regression equation Δj=Δj(λ) in which, for each of a plurality of fiber lengths FL1, FL2, ..., FLm, the wavelength λ is an explanatory variable and the measurement variation Δj of the group delay when light of the wavelength λ is input to an optical fiber having a fiber length FLj is an objective variable. The estimation method according to claim 1,

6. an acquisition step of acquiring a plurality of measurement values ​​obtained by repeatedly measuring a group delay τji when light of a wavelength λi (i is a natural number that is 1 or more and is 0 or less and is n or less) is input to an optical fiber of a fiber length FLj (j is a natural number that is 1 or more and is 0 or less and is m or less) for each of a plurality of fiber lengths FL1, FL2, ..., FLm and each of a plurality of wavelengths λ1, λ2, ..., λn, and calculating a variation Δji of the group delay from the plurality of measurement values; a regression step of deriving the regression equation Δj=Δj(λ) by a least squares method with reference to the measurement variations Δj1, Δj2, ..., Δjn obtained in the acquisition step, The relational equation used in the estimation step is a regression equation corresponding to a fiber length that is closest to the fiber length of the optical fiber to be measured, among the multiple regression equations Δ1=Δ1(λ), ​​Δ2=Δ2(λ), ..., Δm=Δm(λ) obtained in the regression step. The estimation method according to claim 5 .

7. The estimation step is performed only when the fiber length of the optical fiber to be measured is within a predetermined range.

2. The method according to claim 1 .

8. acquiring a group delay when light generated by a light source is input to an optical fiber for each of a plurality of different wavelengths; an estimation step of estimating, for each of a plurality of different wavelengths, a measurement variation of a group delay when light generated by the light source is input to the optical fiber by using the estimation method according to claim 1; a regression process for determining a regression equation τ = τ(λ), in which the wavelength λ is an explanatory variable and the group delay τ when light of the wavelength λ is input to an optical fiber is an objective variable, by a weighted least squares method using weights according to the measurement variation obtained in the estimation process, with reference to the group delay obtained in the acquisition process; and calculating a physical quantity representing an optical characteristic of the optical fiber by using the regression equation τ = τ (λ) obtained in the regression step. A measuring method comprising:

9. The regression equation τ = τ(λ) is expressed as the Sellmeier equation τ = A + Bλ ２ +Cλ －２ That is, 9. The method according to claim 8,

10. The physical quantities include wavelength dispersion D(λ), zero dispersion wavelength λ ０ , or zero dispersion slope slope @ λ ０ and The calculation step calculates the wavelength dispersion D(λ) by: D(λ)=2Bλ−2Cλ －３ Calculating the zero dispersion wavelength λ according to ０ Let λ ０ = (C / B) １／４ or a zero dispersion slope slope @ λ ０ , slope@λ ０ = 8B, 10. The method according to claim 9 .

11. The estimation step is performed only when the fiber length of the optical fiber is within a predetermined range. The estimation method according to claim 5 .

12. An information processing device for implementing the estimation method according to any one of claims 1 to 7 and 11, At least one processor for executing each of the steps.

23. An information processing apparatus comprising:

13. An information processing device for carrying out the measurement method according to any one of claims 8 to 10, At least one processor for executing each of the steps.

23. An information processing apparatus comprising:

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