Analysis device and program

Abstract

One aspect of the present invention provides an analysis device comprising a control unit that executes approximate spectrum acquisition processing for estimating a Raman gain coefficient used for estimating inter-channel stimulated Raman scattering (ISRS) occurring in a target fiber, which is an optical fiber transmission path that is an analysis target used in an optical communication system of a design target, wherein the Raman gain coefficient obtained in the approximate spectrum acquisition processing consists of a Raman gain coefficient for each offset frequency, indicated by a result obtained by using a predetermined approximation to approximate a spectrum in a design offset band, which is a predetermined offset frequency band, among the spectra of the Raman gain coefficients of the target fiber; and the predetermined approximation satisfies at least a first approximation condition prescribing that the Raman gain coefficient in an offset frequency band, within the design offset band, in which the absolute value of the offset frequency is greater than a Raman shift frequency, is linearly approximated by a linear function having a non-zero slope.

Description

Analysis device and program

[0001] The present invention relates to an analysis device and a program.

[0002] To increase the capacity of optical communication systems, studies are underway to expand the wavelength division multiplexing (WDM) signal bandwidth. In broadband WDM transmission systems, which use such wider WDM signal bandwidths, significant power transitions occur from shorter wavelength channels to longer wavelength channels due to inter-channel stimulated Raman scattering (ISRS) occurring in the optical fiber transmission line (Fig. 8).

[0003] This results in wavelength dependency in the signal power conditions that maximize the total system capacity, making it necessary to design a wideband WDM transmission system that takes into account the power transitions between signals due to ISRS.

[0004] Incidentally, the ISRS can be estimated by sequentially analyzing the following coupled equation (see, for example, Non-Patent Document 1) in the longitudinal direction of the optical fiber transmission line, with the signal light spectrum at the input end of the optical fiber transmission line as a boundary value.

[0005]

[0006] where P ｉ represents the power of the i-th WDM channel, and f ｉ is the center frequency of the i-th WDM channel, and f １ <f ２ <...<f （Ｎ－１） <f Ｎ There is a relationship between Ｒ (f ｓ , f ｐ ) is the center frequency f ｓ The channel is regarded as an amplified signal by ISRS, and f ｐ represents the Raman gain coefficient when the channel is considered to be the ISRS pump light.

[0007] α(f ｉ) represents the power attenuation coefficient of the optical fiber transmission line. To estimate ISRS with higher accuracy, the frequency-dependent Raman gain coefficient C Ｒ (f ｓ , f ｐ ) needs to be more accurately incorporated into the calculations.

[0008] Incidentally, one possible technique for incorporating the Raman gain coefficient into the calculation is to estimate the ISRS using a measured Raman gain coefficient spectrum. However, this method has the following problems. One is that Raman gain coefficient spectrum data measured in advance for each type of fiber used for transmission is required. Another is that because the value of the Raman gain coefficient at the frequency interval of the WDM signal to be estimated is required, an interpolation calculation of the Raman gain coefficient spectrum is required, which complicates the calculation.

[0009] Therefore, an approximated Raman gain coefficient spectrum is used when operating an optical communication system. Triangular approximation (see, for example, Non-Patent Document 2) has been used as an approximation method up to now. Triangular approximation will be explained using the diagram.

[0010] 9 shows the Raman gain coefficient spectrum (frequency dependence of Raman gain efficiency). The horizontal axis represents the offset frequency, and the vertical axis represents the normalized Raman gain efficiency. The offset frequency is the frequency of the signal light f ｓ to pump light frequency f ｐ The pump light frequency is equal to or higher than the signal light frequency. Therefore, the offset frequency is a negative value. In other words, the Raman gain coefficient spectrum is data that indicates the offset frequency dependency of the coupling coefficient.

[0011] The solid line represents the measured Raman gain coefficient spectrum. The dotted line represents the result of triangular approximation for the spectrum represented by the solid line. The triangular approximation is an approximation performed under a first assumption and a second assumption. The first assumption is that the Raman gain efficiency increases linearly with respect to the offset frequency within a frequency range in which the absolute value of the offset frequency is smaller than the Raman shift frequency. The second assumption is that the Raman gain coefficient is zero within a frequency range in which the absolute value of the offset frequency is larger than the Raman shift frequency. The Raman shift frequency is the offset frequency at which the Raman gain coefficient is maximized, which is approximately −14 THz.

[0012] When the triangular approximation is used, the frequency dependence of the Raman gain coefficient is expressed by the following equation (2).

[0013]

[0014] Here, C Ｒ、ｍａｘ represents the maximum value of the Raman gain coefficient spectrum, and f Ｒｓ represents the Raman shift frequency.

[0015] S. Tariq & JC Palais, A computer model of non-dispersion-limited stimulated Raman scattering in optical fiber multiple-channel communications. Journal of lightwave technology, 11(12), 1914-1924 (1993).D. Semrau, R. Killey & P. ​​Bayvel, Achievable rate degradation of ultra-wideband coherent fiber communication systems due to stimulated Raman scattering. Optics express, 25(12), 13024-13034 (2017). E. Pincemin, D. Grot, L. Bathany, S. Gosselin, M. Joindot, S. Bordais & JM Delavaux, Raman gain efficiencies of modern terrestrial transmission fibers in S-, C-and L-band. In Nonlinear Guided Waves and Their Applications (p. NLTuC2). Optica Publishing Group (2002, September).

[0016] Incidentally, the WDM signal band used in conventional optical communication systems has been limited to the C+L band (approximately 10 THz), which is below the Raman shift frequency. Therefore, even with triangular approximation, the accuracy of ISRS estimation has not been so poor.

[0017] However, as mentioned above, in recent years, the expansion of the WDM signal bandwidth has been considered. As the WDM signal bandwidth expands, the accuracy of the triangular approximation deteriorates, and the accuracy of ISRS estimation decreases. As a result, the probability that the optical communication system will not operate properly increases. In other words, the probability that an event unexpected by the designer will occur in an optical communication system implemented based on the design increases. Figure 10 shows an example of the results of verifying the decrease in the accuracy of ISRS estimation.

[0018] Fig. 10 shows an example of the error of the estimated ISRS value relative to the actually measured value for a C+L+U band WDM signal (bandwidth approximately 16 THz). The horizontal axis of Fig. 10 represents wavelength, and the vertical axis represents the error of the estimated ISRS value. The solid line represents the estimation error of the ISRS when the actually measured Raman gain efficiency spectrum is used. The dotted line represents the estimation error of the ISRS when a triangular approximation is used.

[0019] 10 shows that the error in the ISRS estimate using the triangular approximation is larger than the error in the ISRS estimate using the measured Raman gain efficiency spectrum. More specifically, FIG. 10 shows that the error in the ISRS estimate using the triangular approximation increases at both ends of the band, unlike the error in the ISRS estimate using the measured Raman gain efficiency spectrum.

[0020] In view of the above circumstances, an object of the present invention is to provide a technique for reducing the probability of an event occurring that is not anticipated by a designer in an optical communication system.

[0021] One aspect of the present invention is an analysis device that includes a control unit that executes an approximate spectrum acquisition process to estimate a Raman gain coefficient used to estimate inter-channel stimulated Raman scattering (ISRS) that occurs in a target fiber that is an optical fiber transmission line that is an analysis target used in an optical communication system that is a design target, wherein the Raman gain coefficients obtained by the approximate spectrum acquisition process are Raman gain coefficients for each offset frequency that are indicated by a result of approximating, by a predetermined approximation, a spectrum in a design offset band that is a predetermined offset frequency band among the spectrum of the Raman gain coefficients of the target fiber, and the predetermined approximation satisfies at least a first approximation condition that the Raman gain coefficient in an offset frequency band within the design offset band has an offset frequency band whose absolute value is larger than the Raman shift frequency, and is linearly approximated by a linear function with a non-zero slope.

[0022] One aspect of the present invention is a program for causing a computer to function as the above-described analysis device.

[0023] The present invention makes it possible to reduce the probability of an event occurring in an optical communication system that is not anticipated by the designer.

[0024] 1 is an explanatory diagram illustrating an analysis device according to an embodiment; a diagram illustrating a first example of a result of a first approximation according to an embodiment; a diagram illustrating a second example of a result of the first approximation according to an embodiment; a diagram illustrating an example of a hardware configuration of an analysis device 1 according to an embodiment; a flowchart illustrating an example of a flow of processing executed by an analysis device according to an embodiment; a diagram illustrating a first example of a result of a second approximation according to a modified example; a diagram illustrating a second example of a result of the second approximation according to a modified example; a first diagram illustrating the prior art; a second diagram illustrating the prior art; and a third diagram illustrating the prior art.

[0025] (Embodiment) Fig. 1 is an explanatory diagram illustrating an analysis device 1 according to an embodiment. The analysis device 1 is a device that acquires values ​​used in the design of an optical communication system to be designed. More specifically, the analysis device 1 estimates a Raman gain coefficient used to estimate inter-channel stimulated Raman scattering (ISRS) occurring in an optical fiber transmission line to be analyzed (hereinafter referred to as a "target fiber") used in the optical communication system to be designed. The analysis device 1 also estimates ISRS based on the estimated Raman gain coefficient.

[0026] Hereinafter, the process of estimating ISRS based on the estimated Raman gain coefficient is referred to as ISRS estimation process. The ISRS may be estimated by any known technique, and may be obtained, for example, by executing equation (1). For example, the ISRS is the channel distribution of the value obtained by subtracting the fiber loss α of the optical fiber transmission line from the power of each WDM channel obtained by solving equation (1).

[0027] The analysis device 1 includes a control unit 11 including a processor 91 such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Network Processing Unit) and a memory 92 connected via a bus.

[0028] The control unit 11 executes an approximate spectrum acquisition process. The approximate spectrum acquisition process is a process for estimating a Raman gain coefficient used to estimate ISRS generated in the target fiber. The control unit 11 executes the ISRS estimation process to estimate the ISRS based on the result obtained by the approximate spectrum acquisition process. Specifically, the result obtained by the approximate spectrum acquisition process is the Raman gain coefficient obtained by executing the approximate spectrum acquisition process.

[0029] In the approximate spectrum acquisition process, a result of approximating the Raman gain coefficient spectrum in a design offset band, which is a predetermined offset frequency band, is obtained by a predetermined approximation that satisfies at least a first approximation condition. That is, the approximate spectrum acquisition process is a process of obtaining a result of approximating the Raman gain coefficient spectrum in the design offset band by an approximation that satisfies at least the first approximation condition. The Raman gain coefficients for each offset frequency indicated by the approximation result are the Raman gain coefficients obtained by the approximate spectrum acquisition process.

[0030] The offset frequency band is a band of offset frequencies. Specifically, the predetermined offset frequency band is an offset frequency band in which ISRS generated in the target fiber can be estimated and the Raman gain coefficient used for that can be obtained.

[0031] The offset frequency is the result of subtracting the pump light frequency fp from the signal light frequency fs. The pump light frequency is equal to or higher than the signal light frequency. Therefore, the offset frequency is a negative value.

[0032] The first approximation condition is a condition that the absolute value of the offset frequency is greater than the Raman shift frequency, and the Raman gain coefficient in the offset frequency band within the design offset band is linearly approximated by a linear function with a non-zero slope. Hereinafter, an approximation that satisfies the first approximation condition will be referred to as the first approximation.

[0033] FIG. 2 is a diagram showing a first example of the result of the first approximation in the embodiment. More specifically, FIG. 2 is a diagram showing an example of the result of approximating the Raman gain coefficient spectrum in the design offset band by the first approximation. The horizontal axis of FIG. 2 represents the offset frequency, and the vertical axis represents the normalized Raman gain efficiency. Note that the normalization in the term normalized Raman gain efficiency means dividing the pre-standard Raman gain efficiency of each offset frequency by the maximum value of the pre-standard Raman gain efficiency. "Accurate spectrum" represents the actually measured spectrum. "Approximation method 1" represents the result of the first approximation.

[0034] Specifically, the first approximation shown in FIG. 2 is an approximation expressed by the following equation (3).

[0035]

[0036] Value C Ｒ (f ｓ , f ｐ ) is the center frequency f ｓ The channel is regarded as an amplified signal by ISRS, and f ｐ represents the Raman gain coefficient when the channel is considered to be the ISRS pump light.

[0037] f Ａ represents a value obtained by subtracting the Raman shift frequency from an offset frequency at the edge of the design offset band that has an absolute value greater than that of the Raman shift frequency. The Raman gain coefficient can be calculated from the offset frequency using equation (3).

[0038] In the approximate spectrum acquisition process, f Ｒｓ and f Ａ are the optimization variables. Therefore, in the example of equation (3), the variable f Ｒｓ and variable f Ａ and to find the optimum variable f that approximates the Raman gain coefficient spectrum. Ｒｓ and variable f Ａ The approximate spectrum acquisition process is carried out to obtain the values ​​of the variable f Ｒｓ and variable f Ａ The initial values ​​of and may be well-known values ​​such as those described in Non-Patent Document 3 below.

[0039] By the way, value C Ｒ、ｍａｘ represents the maximum value of the Raman gain coefficient within the design offset band. In fact, the spectrum of the Raman gain coefficient depends on the type of fiber. Therefore, the value C Ｒ、ｍａｘ is a known value that is determined once the type of fiber is determined. Therefore, in the approximate spectrum acquisition process, the value C Ｒ、ｍａｘ is not an optimization variable, but a fixed value in the optimization. Ｒ、ｍａｘ For example, a known value such as the value described in Non-Patent Document 3 may be used for the value C. Ｒ、ｍａｘis 0.39W －１ km －１ It was.

[0040] In the example of FIG. 2, the optimization result is f Ｒｓ is -14 THz, and f Ａ was -3 THz.

[0041] FIG. 2 shows that the approximation is performed with higher accuracy than the results of the triangular approximation described in Non-Patent Document 2 (FIG. 9).

[0042] 3 is a diagram showing a second example of the result of the first approximation in the embodiment. More specifically, FIG. 3 is a diagram showing the ISRS estimation error (dashed line) when the first approximation is performed on a C+L+U band WDM signal. "Accurate spectrum" indicates the actually measured spectrum. "Triangular approximation" indicates the result of the triangular approximation described in Non-Patent Document 2. "Approximation method 1" indicates the result of the first approximation. In the example of FIG. 3 as well, the first approximation was specifically an approximation expressed by Equation (3).

[0043] 3 shows that when the first approximation is used, the ISRS estimation errors at both ends observed when the triangular approximation is used are reduced, and ISRS estimation is performed close to that when the "accurate spectrum" is used. Note that the calculation time when designing an optical communication system using the first approximation is approximately two-thirds of the calculation time when designing an optical communication system using the "accurate spectrum" with interpolation.

[0044] 4 is a diagram showing an example of the hardware configuration of the analysis device 1 according to an embodiment. The analysis device 1 includes a control unit 11 having a processor 91 and a memory 92 connected by a bus, and executes a program. By executing the program, the analysis device 1 functions as a device including the control unit 11, an interface unit 12, and a storage unit 13.

[0045] More specifically, the processor 91 reads out a program stored in the storage unit 13 and stores the read out program in the memory 92. The processor 91 executes the program stored in the memory 92, whereby the analysis device 1 functions as a device including the control unit 11, the interface unit 12, and the storage unit 13.

[0046] The control unit 11 controls the operation of each functional unit included in the analysis device 1. The control unit 11 executes, for example, an approximate spectrum acquisition process. The control unit 11 executes, for example, an ISRS estimation process.

[0047] The control unit 11 acquires information indicating a design offset band (hereinafter referred to as "design band information") and information indicating the spectrum of the Raman gain coefficient of the target fiber (hereinafter referred to as "target spectrum information"), for example, via the interface unit 12. Based on the design band information and the target spectrum information, the value C Ｒ、ｍａｘ is obtained.

[0048] By executing the approximate spectrum acquisition process, the control unit 11 uses the acquired design band information and target spectrum information to obtain a result of approximating the spectrum in the design offset band indicated by the design band information, out of the spectrum indicated by the target spectrum information.

[0049] The control unit 11 acquires, for example, input frequency information, attenuation coefficient information, and length information via the interface unit 12. The input frequency information is information indicating the frequency of an optical signal input to the target fiber. The attenuation coefficient information is information indicating the power attenuation coefficient of the target fiber. The attenuation coefficient is a known value depending on the type of fiber. The length information is information indicating the length of the target fiber.

[0050] The control unit 11 executes, for example, an ISRS estimation process to estimate ISRS generated in the target fiber using input frequency information, attenuation coefficient information, length information, and the Raman gain coefficient obtained by executing the approximate spectrum acquisition process.

[0051] The control unit 11 acquires, for example, information stored in the storage unit 13. Specifically, the process of acquiring information stored in the storage unit 13 is a read process.

[0052] The interface unit 12 includes a communication interface for connecting the analysis apparatus 1 to an external device. The interface unit 12 communicates with the external device via wired or wireless communication. The external device is, for example, a device that transmits the design band information and the target spectrum information. In such a case, the interface unit 12 acquires the design band information and the target spectrum information by communicating with the device that transmits the design band information and the target spectrum information.

[0053] The external device is, for example, a device that has transmitted the input frequency information, the attenuation coefficient information, and the length information. In this case, the interface unit 12 acquires the input frequency information, the attenuation coefficient information, and the length information by communicating with the device that has transmitted the input frequency information, the attenuation coefficient information, and the length information.

[0054] The interface unit 12 may be configured to include input devices such as a mouse, keyboard, touch panel, etc. The interface unit 12 may be configured as an interface that connects these input devices to the analysis device 1. In this way, the input devices of the interface unit 12 accept input of various information to the analysis device 1 via wired or wireless connections. Note that the various data acquired by the communication interface of the interface unit 12 described above does not necessarily have to be acquired by the communication interface of the interface unit 12, and may be input to the input device.

[0055] The interface unit 12 outputs, for example, various types of information. The interface unit 12 includes a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro-Luminescence) display. The interface unit 12 may be configured as an interface that connects these display devices to the analysis device 1. The interface unit 12 outputs, for example, information input to an input device or a communication interface of the interface unit 12.

[0056] The storage unit 13 is configured using a computer-readable storage medium device (non-transitory computer-readable recording medium) such as a magnetic hard disk device or a semiconductor storage device. The storage unit 13 stores various information related to the analysis device 1. The storage unit 13 stores, for example, various information generated by the operation of the control unit 11. The storage unit 13 stores, for example, information acquired by the interface unit 12.

[0057] 5 is a flowchart showing an example of the flow of processing executed by the analysis apparatus 1 according to the embodiment. The control unit 11 acquires design band information, target spectrum information, input frequency information, attenuation coefficient information, and length information (step S101). Next, the control unit 11 executes an approximate spectrum acquisition process (step S102). In the approximate spectrum acquisition process, the design band information and target spectrum information acquired in step S101 are used.

[0058] Next, the control unit 11 executes an ISRS estimation process (step S103). In the ISRS estimation process, the result obtained in step S102 and the input frequency information, attenuation coefficient information, and length information obtained in step S101 are used.

[0059] Next, the control unit 11 controls the operation of the interface unit 12 to output the ISRS obtained in step S103 to a predetermined output destination (step S104). Note that the predetermined output destination may be a display device included in the interface unit 12. In step S104, the control unit 11 may also control the operation of the interface unit 12 to output the result of the approximate spectrum acquisition process to the predetermined output destination.

[0060] The analysis device 1 of this embodiment configured as described above includes a control unit 11 that executes an approximate spectrum acquisition process. The approximate spectrum acquisition process is a process for obtaining an approximated result of a Raman gain coefficient spectrum in a predetermined offset frequency band using an approximation that satisfies at least a first approximation condition. The approximate spectrum acquisition process obtains an approximation result with higher accuracy than triangular approximation, thereby enabling estimation of an ISRS that more closely reflects actual physical phenomena. As a result, it becomes possible to design an optical communication system that more closely reflects actual physical phenomena. Therefore, the analysis device 1 can reduce the probability of an event occurring in an optical communication system that is unexpected by the designer.

[0061] (Modification) In the approximated spectrum acquisition process, approximation that satisfies a second approximation condition in addition to the first approximation condition may be performed. The second approximation condition is a condition that a linear approximation having a slope different from the slope of the linear approximation performed on the Raman gain coefficient spectrum of an offset frequency band whose absolute value of the offset frequency is larger than the Raman shift frequency and which is within the design offset band is performed on the Raman gain coefficient spectrum of the Raman frequency band.

[0062] Therefore, the slope of the linear approximation performed on the Raman gain coefficient spectrum in the Raman frequency band may be, for example, 0. Hereinafter, an approximation that satisfies the first and second approximation conditions will be referred to as a second approximation.

[0063] Fig. 6 is a diagram showing a first example of the result of the second approximation in the modified example. More specifically, Fig. 6 is a diagram showing an example of the result of approximating the Raman gain coefficient spectrum in the design offset band by the second approximation. The horizontal axis of Fig. 6 represents the offset frequency, and the vertical axis represents the normalized Raman gain efficiency. "Accurate spectrum" represents the actually measured spectrum. "Approximation method 2" represents the result of the second approximation.

[0064] Specifically, the second approximation shown in FIG. 6 is an approximation expressed by the following equation (4).

[0065]

[0066] f Ｂindicates the Raman frequency band. More specifically, f Ｂ f represents the value obtained by subtracting the offset frequency with the smallest absolute value from the offset frequency with the largest absolute value among the frequencies in the Raman frequency band. Ａ represents a value obtained by subtracting the Raman shift frequency from an offset frequency at the edge of the design offset band that has an absolute value greater than that of the Raman shift frequency. The Raman gain coefficient can be calculated from the offset frequency using equation (4).

[0067] In the approximate spectrum acquisition process, f Ｂ Also f Ｒｓ and f Ａ Therefore, in the example of equation (4), the variable f Ｒｓ and variable f Ａ and variable f Ｂ and to find the optimum variable f that approximates the Raman gain coefficient spectrum. Ｒｓ and variable f Ａ and variable f Ｂ The approximate spectrum acquisition process is carried out to obtain the values ​​of the variable f B The initial value of the variable f Ａ The initial value of the variable f Ｂ Similarly to the initial value of , a known value such as the value described in Non-Patent Document 3 may be used.

[0068] In addition, in the same manner as in the case of the formula (3), the value C Ｒ、ｍａｘ is not an optimization variable, but a fixed value in the optimization. In the example of FIG. Ｒ、ｍａｘ is 0.39W －１ km －１ It was.

[0069] In the example of FIG. 6, the optimization result is f Ｒｓ is -13 THz, and f Ａ is -2.3 THz, and f Ｂ was -1.5 THz.

[0070] FIG. 6 shows that the approximation is performed with higher accuracy than the results of the triangular approximation described in Non-Patent Document 2 (FIG. 9).

[0071] Fig. 7 is a diagram showing a second example of the result of the second approximation in the modified example. More specifically, Fig. 7 is a diagram showing the ISRS estimation error (dashed line) when the second approximation is performed on a C+L+U band WDM signal. "Accurate spectrum" indicates the actually measured spectrum. "Triangular approximation" indicates the result of the triangular approximation described in Non-Patent Document 2. "Approximation method 2" indicates the result of the second approximation. In the example of Fig. 6, the second approximation was specifically the approximation expressed by Equation (4).

[0072] 6 shows that when the second approximation is used, the ISRS estimation error at both ends, which was observed when the triangular approximation was used, is reduced, and ISRS estimation is performed close to that when the "accurate spectrum" is used. Comparing the first and second approximations, the second approximation has a larger area of ​​the Raman gain coefficient spectrum. Therefore, the second approximation has a larger estimated value of the power transition due to ISRS than the first approximation.

[0073] The calculation time when the optical communication system was designed using the second approximation was about two-thirds of the calculation time when the optical communication system was designed using the exact spectrum with interpolation.

[0074] The analysis device 1 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0075] The analysis device 1 may also be implemented using a plurality of information processing devices connected to each other via a network so that they can communicate with each other. In this case, the processes executed by the control unit 11 may be distributed among the plurality of information processing devices.

[0076] The ISRS estimation process may be performed by a device different from the analysis device 1. Even in such a case, the analysis device 1 performs the approximate spectrum acquisition process, which makes it possible to reduce the probability of an event occurring in the optical communication system that is not anticipated by the designer.

[0077] Note that all or part of the functions of the control unit 11, the interface unit 12, and the storage unit 13 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The program may be transmitted via a telecommunications line.

[0078] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0079] REFERENCE SIGNS LIST 1 analysis device, 11 control unit, 12 interface unit, 13 storage unit, 91 processor, 92 memory

Claims

1. An analysis device comprising: a control unit that executes an approximate spectrum acquisition process to estimate a Raman gain coefficient used to estimate inter-channel stimulated Raman scattering (ISRS) occurring in a target fiber, which is an optical fiber transmission line to be analyzed and used in an optical communication system to be designed; wherein the Raman gain coefficient obtained by the approximate spectrum acquisition process is a Raman gain coefficient for each offset frequency indicated by a result of approximating, by a predetermined approximation, a spectrum in a design offset band, which is a predetermined offset frequency band, among the spectrum of the Raman gain coefficients of the target fiber; and wherein the predetermined approximation at least satisfies a first approximation condition that the Raman gain coefficient in an offset frequency band within the design offset band, which is an offset frequency band with an absolute value of the offset frequency greater than the Raman shift frequency, is linearly approximated by a linear function with a non-zero slope.

2. The analysis device according to claim 1, wherein the predetermined approximation further satisfies a second approximation condition that a linear approximation having a slope different from a slope of a linear approximation performed on a Raman gain coefficient spectrum of an offset frequency band within the design offset band, the offset frequency band having an absolute value of the offset frequency greater than the Raman shift frequency, is performed on the Raman gain coefficient spectrum of the Raman frequency band.

3. The analysis device according to claim 1, wherein the control unit executes an ISRS estimation process to estimate ISRS generated in the target fiber based on a result of the approximate spectrum acquisition process.

4. A program for causing a computer to function as the analysis device according to any one of claims 1 to 3.

Images