JP6930950B2 - Measuring device for optical communication system - Google Patents

Description

The present invention relates to a quality measurement technique for an optical communication system, and more particularly to a general-purpose optical signal-to-noise ratio (G-OSNR) measurement technique for an optical communication system.

In an optical communication system, an optical amplifier generates optical noise. Therefore, the optical signal-to-noise ratio (OSNR) is used as one of the parameters for evaluating the quality of the optical communication system. Further, in an optical communication system, the quality of an optical signal deteriorates based on its linear optical characteristics and non-linear optical characteristics. Regarding linear optical characteristics represented by wavelength dispersion, various techniques for electrically compensating have been established at present, and they are no longer the main factors that deteriorate the performance of optical communication systems. On the other hand, for nonlinear optical characteristics such as self-phase modulation, effective compensation technology has not yet been established, which is a major factor in deteriorating the performance of optical communication systems.

Non-Patent Document 1 discloses that quality deterioration of an optical signal due to nonlinear optical characteristics is quantified as nonlinear interference noise. In addition, Non-Patent Document 2 proposes a general-purpose optical signal-to-noise ratio (G-OSNR), which is a quality evaluation parameter of an optical communication system in consideration of optical noise and quantified nonlinear interference noise. Specifically, assuming that the powers of the optical signal, the optical noise, and the nonlinear interference noise are P _CH , P _ASE, and P _NL , respectively, G-OSNR is obtained by P _CH / (P _ASE + P _NL ).

P. Poggiolini, et. al. , "The GN-Model of Fiber Non-Linear Propagation and Applications Applications", JLT-32, no. 4, pp. 694-721, February 15, 2014 Mateo, et. al. , SubOptic 2016, Paper Th1A. 1, 2016

Non-Patent Document 1 proposes to obtain the amount of non-linear interference noise by using a calculation formula called GNRF (Gaussian Noise Reference Formula). _{Specifically, it is proposed to obtain the power spectral density GNLI} (f) of the nonlinear interference noise at the frequency f by the following equation (1).

（１）

(1)

It should be noted that each variable of the above equation (1) is various parameters such as loss, wavelength dispersion, and dispersion slope of the target optical communication system, but the details thereof are described in Non-Patent Document 1 and are here. Let's omit it. _{Non-Patent Document 1 discloses that the power spectral density GNLI} (f) of nonlinear interference noise is theoretically obtained by performing a very complicated double integral calculation based on various parameters of an optical communication system. ing. However, Non-Patent Document 1 does not disclose a specific method for measuring _{the power spectral density GNLI (f) of nonlinear interference noise.}

The present invention provides a measuring device capable of measuring the power spectral density of nonlinear interference noise.

According to one aspect of the present invention, the measuring device has an output means that generates optical signals of the first frequency, the second frequency, and the third frequency and outputs the optical signals to the optical transmission line to be measured, and the optical transmission line outputs the signals. A measuring means for measuring the power of the optical signal of the fourth frequency generated in the optical transmission line by mixing the optical signals of the first frequency, the second frequency, and the third frequency with four light waves, and the fourth frequency. It is characterized in that it includes a determination means for determining the power spectrum density of nonlinear interference noise generated in the optical transmission line by multiplying the power of an optical signal by an adjustment value.

According to the present invention, the power spectral density of nonlinear interference noise can be measured.

The block diagram of the measuring apparatus according to one Embodiment. The figure which shows the relationship of the frequency of the optical signal output by the measuring apparatus by one Embodiment. The figure which shows the coefficient information by one Embodiment. The block diagram of the measuring apparatus according to one Embodiment. The figure which shows the model for generating the coefficient information by one Embodiment. The figure which shows the mode of measurement by one Embodiment.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In each of the following figures, components that are not necessary for the description of the embodiment will be omitted from the drawings. Further, the following embodiments are examples, and the present invention is not limited to the contents of the embodiments.

The present inventor has an optical signal having a frequency f generated by mixing three frequencies f1, f2 and f3 = f1 + f2 + f in the above equation (1) for _{obtaining a GNLI (f).} Therefore, we have found that the power spectral density of the nonlinear interference noise can be obtained by measuring the power and multiplying the measured power by an appropriate adjustment value, and have reached the present invention. The power of the optical signal of the frequency f generated by the non-degenerate four-wave mixing of the three frequencies f1, f2 and f3 = f1 + f2 + f can theoretically be obtained by the following equation (2).

なお、上記式（２）の各パラメータは、式（１）と同様である。

Each parameter of the above equation (2) is the same as that of the equation (1).

<First Embodiment>
FIG. 1 is a configuration diagram of a measuring device according to the present embodiment. The measuring device has three light source units 11 to 13, a multiplexing unit 2, an optical power measuring unit 3, and a calculation unit 4. The power spectrum density of the nonlinear interference noise of the optical communication system (optical transmission line) 80 is measured. Further, the amount of nonlinear interference noise can be obtained based on the measured power spectral density of the nonlinear interference noise, and the G-OSNR can be obtained.

The light source unit 11 generates an optical signal having a frequency f1 and outputs it to the multiplexing unit 2, the light source unit 12 generates an optical signal having a frequency f2 and outputs it to the multiplexing unit 2, and the light source unit 13 generates an optical signal having a frequency f3 =. An optical signal of f1 + f2-f4 is generated and output to the multiplexing unit 3. It is desirable that the light source units 11 to 13 are configured to generate an optical signal whose polarization state changes with time. For example, each of the light source units 11 to 13 may be provided with a plurality of light sources that generate optical signals that are incoherent to each other. In this case, the light source units 11 to 13 can generate an optical signal whose polarization state changes with time by combining optical signals generated by a plurality of light sources. Further, the light source units 11 to 13 may be provided with a single light source and a polarization adjuster that changes the polarization state of the optical signal generated and output by the single light source with time. .. The multiplexing unit 2 frequency-multiplexes (wavelength-multiplexes) optical signals of frequencies f1, f2, and f3 and outputs them to the optical communication system 80 to be measured.

Here, in the optical communication system 80, an optical signal having a frequency f4 is generated by non-degenerate four-wave mixing by three optical signals having frequencies f1, f2, and f3 = f1 + f2-f4. In the present embodiment, when the four optical signals of frequencies f1, f2, f3 and f4 are arranged on the frequency axis, the frequencies f1, f2 and Set f3. The magnitude relation of the four frequencies f1, f2, f3 and f4 is arbitrary. 2 (A) and 2 (B) show an example of frequency arrangement, respectively.

In FIG. 2A, the frequency f4 is the lowest, the frequency f1 is the second lowest, the frequency f2 is the second highest, and the frequency f3 = f1 + f2-f4 is the highest. On the other hand, in FIG. 2B, the frequency f1 is the lowest, the frequency f3 = f1 + f2-f4 is the second lowest, the frequency f4 is the second highest, and the frequency f2 is the highest. There are many possible frequency arrangements other than those shown in FIG.

The optical power measuring unit 3 measures the power of the optical signal having a frequency f4 generated by the non-degenerate four-wave mixing, and outputs the power to the arithmetic unit 4. The calculation unit 4 stores, for example, coefficient information indicating the correspondence between the frequency and the coefficient as shown in FIG. The calculation unit 4 determines the coefficient c4 of the frequency f4 based on the coefficient information and sets it as an adjustment value. _{Then, the calculation unit 4 obtains GNLI} (f4) by multiplying the power of the optical signal of the frequency f4 measured by the optical power measurement unit 3 and the adjustment value. Hereinafter, how to obtain the coefficient information stored in advance in the calculation unit 4 will be described.

First, as shown in FIG. 5, a model of an optical communication system having the same number of spans as the optical communication system 80 to be measured is defined. In addition, one span is a section from immediately after one optical amplifier section to the next optical amplifier section. In this example, the number of spans of the optical communication system 80 is set to 5, and therefore the number of spans of the model shown in FIG. 5 is also set to 5. In FIG. 5, the length of each span (span length) is 80 km.

_{First, for the defined model, the GNLI} (f) at each frequency f is calculated by the formula (1) disclosed in Non-Patent Document 1. Further, the power of the optical signal generated by the non-degenerate four-wave mixing in the defined model based on the equation (2) is also calculated for each frequency f. When Δf is increased, the power of the optical signal generated by the non-degenerate four-wave mixing greatly increases or decreases in a predetermined period on the frequency axis. Therefore, Δf is set so that the increase / decrease in the power of the optical signal generated by the non-degenerate four-wave mixing on the frequency axis becomes smaller than the predetermined value. Then, for each frequency f _{, the coefficient information can be created by dividing the calculated GNLI} by the power of the optical signal generated by the non-degenerate four-wave mixing.

As described above, in the present embodiment, the coefficient information indicating the correspondence between the frequency and the coefficient is calculated in advance based on the model having the same number of spans as the optical communication system 80 to be measured and stored in the calculation unit 4. Then, the calculation unit 4 determines the power of the optical signal of the frequency f4 generated by the non-degenerate four-wave mixing measured by the optical power measurement unit 3 and the adjustment value based on the coefficient c4 of the frequency f4 determined from the coefficient information. By multiplying, _GNLI (f4) can be easily measured. Then, the amount of non-linear interference noise can be measured by measuring _GNLI (f4) while changing the frequency f4 over the bandwidth used in the optical communication system 80 to be measured. In addition, G-OSNR can be measured by measuring the power of optical noise and the power of optical signals in parallel. If the coefficient value in the coefficient information does not change so much depending on the frequency, the non-linear interference noise can be simply multiplied by the bandwidth used in the optical communication system 80 to be measured by _{GNLI (f4).} The amount can be measured. Therefore, for example, with respect to the coefficient information, Δf is determined when the change in the coefficient due to the frequency is the smallest while changing Δf, and the relationship between the frequency and the coefficient at that time is set in the coefficient information. be able to.

<Second embodiment>
Subsequently, the second embodiment will be described focusing on the differences from the first embodiment. For example, in the first embodiment, when the power of the optical signal having a frequency f4 generated by the non-reduced four light wave mixing is weak and is equal to or lower than the optical noise level, the optical power measuring unit 3 has the frequency f4 generated by the non-reduced four light wave mixing. The power of the optical signal cannot be measured. _{The present embodiment enables the optical power measuring unit 3 to measure GNLI} (f4) even when the power of the optical signal having a frequency f4 generated by the non-degenerate four-wave mixing cannot be directly measured by the optical power measuring unit 3.

FIG. 4 is a configuration diagram of a measuring device according to the present embodiment. The same reference numerals are used for the same components as those in FIG. 1, and the description thereof will be omitted. In the present embodiment, any one of the three optical signals output by the three light source units 11 to 13 is modulated with predetermined data, for example, random data to obtain modulated light, and other light. The signal remains continuous light. The modulation method is arbitrary. In this example, the optical signal of the frequency f1 output by the light source unit 11 is modulated, and thus the modulation unit 5 is provided between the light source unit 11 and the multiplexing unit 2.

In the optical communication system 80, an optical signal having a frequency of f4 is generated by unreduced four-light wave mixing by three optical signals having frequencies f1, f2, and f3 = f1 + f2-f4. The optical signal having the frequency f4 is also modulated light. The output of the optical communication system 80 is first connected to the optical power measuring unit 3, and the optical power measuring unit 3 measures the power P1 of the modulated light having a frequency f1. Subsequently, the output of the optical communication system 80 is connected to the optical filter 6. The optical filter 6 is a variable filter capable of changing the pass band, and the optical filter 6 is first set to pass modulated light having a frequency f1. Therefore, the photoelectric conversion unit 7 which is a photodiode outputs the first modulated electric signal based on the modulated light of the frequency f1, and the power measuring unit 8 measures the power E1 of the first modulated electric signal. Subsequently, the optical filter 6 is set so as to pass the modulated light having the frequency f4. Therefore, the photoelectric conversion unit 7 outputs the fourth modulated electric signal based on the modulated light of the frequency f4, and the power measuring unit 8 measures the power E4 of the fourth modulated electric signal. The power measuring unit 8 can measure the power E4 of the fourth modulated electric signal because the optical noise is random and does not appear in the output of the photoelectric conversion unit 7. The power measuring unit 8 outputs the powers E1 and E4 of the two measured electrical signals to the arithmetic unit 4.

Here, assuming that the power of the modulated light of the frequency f4 is P4, the ratio (P4 / P1) of the power P1 of the modulated light of the frequency f1 to the power P4 is the power of the first modulated electric signal based on the modulated light of the frequency f1. It is equal to the ratio (E4 / E1) of E1 to the power E4 of the fourth modulated electrical signal based on the modulated light of frequency f4. Therefore, the arithmetic unit 4 can obtain the power P4 of the optical signal having the frequency f4 generated by the non-degenerate four-wave mixing by P4 = P1 × E4 / E1. _{After that, as in the first embodiment, the calculation unit 4 can obtain the GNLI} (f4) by multiplying the obtained power P4 by the adjustment value determined from the coefficient information.

_{With the above configuration, GNLI} (f4) can be obtained even when the power of the optical signal having a frequency f4 generated by the non-degenerate four-wave mixing cannot be directly measured due to optical noise.

<Third Embodiment>
Subsequently, the third embodiment will be described focusing on the differences from the first embodiment. In the first embodiment, the coefficient information is generated based on a model having the same number of spans as the optical communication system 80 to be measured. Therefore, in order to measure an optical communication system having various span numbers, coefficient information is generated based on a model with various span numbers, and the coefficient information to be used is selected according to the number of spans of the optical communication system to be measured. I needed it. In the present embodiment, only the coefficient information generated based on one model having a predetermined number of spans is stored in the calculation unit 4, and the coefficient information is corrected according to the number of spans of the optical communication system 80 to be measured. The configuration to be used will be described.

First, the calculation unit 4 stores, for example, coefficient information based on a 5-span model shown in FIG. 3 and the above-mentioned equation (1) for _{obtaining GNLI (f).} Further, the calculation unit 4 sets the number of spans of the optical communication system 80 to be measured.

Calculating portion 4, the frequency f4 generated in a non-degenerate four-wave mixing, _G and NLI (f4) in the case of 5 span a model, the optical communication system 80 of the measuring object with _G NLI (f4) _in the number of spans The ratio is used as the span number correction value, and is calculated based on the equation (1). Then, the calculation unit 4 obtains an adjustment value at the frequency f4 in the number of spans of the optical communication system 80 by multiplying the coefficient c4 determined from the coefficient information by the span number correction value, and obtains this by non-reduced four-wave mixing. _GNLI (f4) is obtained by multiplying the power of the generated optical signal of frequency f4.

_{For example, in order to calculate the coefficient information for a certain model, it is necessary to calculate GNLI} (f) for each frequency f, that is, with the frequency f as a variable, based on the equation (1). The amount is enormous. In other words, for each of the models with a plurality of spans, a huge amount of calculation must be performed to create coefficient information.

In the present embodiment, one coefficient information is created in advance, and only the span correction value of the frequency f4 to be measured is obtained by the equation (1). That is, instead of calculating the equation (1) for each of the plurality of frequencies f, only the calculation for obtaining the ratio between the two span numbers (the other parameters are the same) is performed only for the predetermined frequency f4. Therefore, the amount of calculation for obtaining the span correction value is not large.

_{With the above configuration, GNLI} (f4) can be measured with one coefficient information for optical communication systems having various span numbers. The present embodiment can also be applied to the second embodiment.

<Fourth Embodiment>
_{In the first embodiment and the second embodiment, the GNLI} (f4) is measured using the coefficient information obtained based on the model having the same number of spans as the optical communication system 80 to be measured, and in the third embodiment, the coefficient is measured. The configuration for measuring the optical communication system 80 having a span number different from the model used for creating the information has been described. Here, as shown in FIG. 5, in the model used for creating the coefficient information, the parameters (span length, wavelength dispersion, dispersion slope) of each span are assumed to be the same for simplification of calculation. However, even if the number of spans of the model is the same as that of the optical communication system 80 to be measured, the span length, wavelength dispersion, and dispersion slope of each span are not necessarily the same in the optical communication system 80 to be measured. _{Hereinafter, a configuration for obtaining GNLI} (f4) with higher accuracy as compared with the first to third embodiments will be described.

<Span length>
According to the research and investigation of the present inventor, the variation in the span length of each span of the optical communication system does not affect the measurement result, and only the average value of the span length of each span of the optical communication system affects the measurement result. It turned out. Therefore, coefficient information corresponding to the average value of the plurality of span lengths is created, and the coefficient information corresponding to the average value closest to the average value of the span lengths of the optical communication system 80 to be measured is selected and used. Therefore, the _GNLI (f4) can be measured with high accuracy. Alternatively, in addition to the coefficient information obtained by a model having the same length of each span (80 km in FIG. 5), the span length showing the relationship between the average value of the span length and the span length correction value for correcting the coefficient information. The correction information may be stored in the calculation unit 4. In this case, the calculation unit 4 corrects the coefficient determined by the coefficient information with the span length correction value determined by the span length correction information to obtain an adjustment value, _{and determines GNLI} (f4) based on this adjustment value.

<Wavelength dispersion>
According to the research and investigation of the present inventor, the wavelength dispersion (value per unit distance) of each span, as well as the span length, affects the measurement result if the dispersion of the entire optical communication system and the dispersion of the model are the same. It turned out not. Therefore, similarly to the span length described above, the coefficient information corresponding to the plurality of variances is stored in the calculation unit 4, and the coefficient information corresponding to the variance closest to the variance of the optical communication system to be measured is used. _Therefore, G NLI (f4) can be obtained more accurately. Further, as with the span length, the coefficient obtained from one coefficient information can be corrected and used based on the variance of the optical communication system to be measured. In this case, dispersion correction information indicating the relationship between the dispersion and the dispersion correction value for correcting the coefficient is created in advance and stored in the calculation unit 4.

<Dispersed slope>
From the research and investigation of the present inventor, it was found that the variation of the dispersion slope of each span affects the measurement result in addition to the average value for the dispersion slope (value per unit distance). _{Therefore, the GNLI} (f4) can be obtained more accurately by creating the coefficient information according to the combination of the value of the variance slope to be measured and the standard deviation (or variance). Alternatively, the dispersion slope correction information indicating the relationship between the dispersion slope value and standard deviation (or dispersion) and the dispersion slope correction value may be obtained in advance and stored in the calculation unit 4. In this case, the calculation unit 4 obtains the dispersion slope correction value based on the dispersion slope of the entire optical communication system 80 to be measured and the standard deviation (or dispersion) of the dispersion slope of each span, and uses the obtained dispersion slope correction value. By correcting the coefficient and _obtaining the adjustment value, the GNLI (f4) can be determined more accurately.

It should be noted that the correction of the coefficient by the span length, the wavelength dispersion and the dispersion slope, or the use of the coefficient information according to the span length, the wavelength dispersion and the dispersion slope can be used in combination.

<Fifth Embodiment>
In the first to fourth embodiments, it was assumed that the gain profile (relationship between frequency and gain) of the optical communication system 80 to be measured was flat. In a normal wavelength division multiplexing optical communication system, an equalizer that suppresses fluctuations in the gain of each wavelength is used, and this assumption is generally valid. However, when the gain profile of the optical communication system 80 to be measured is not flat, the measurement result differs depending on the frequency f4.

_{Here, if GNLI} is measured while changing the frequency f4 over the bandwidth used in the optical communication system 80 to be measured, there is no problem because the amount of nonlinear interference noise is obtained based on the measured value. _{When the non-linear interference noise amount is simply obtained by multiplying the GNLI} measured at the frequency f4 by the bandwidth used in the optical communication system 80 to be measured, the measurement result fluctuates according to the value of the frequency f4.

Therefore, when the gain profile of the optical communication system 80 to be measured is not flat, the frequency f4 is set to a frequency within which the gain is the average value of the gains of the signal bandwidth or a predetermined range including the average value. Therefore, the error of the measured value can be suppressed. As the gain is higher, _{the value of G NLI} increases and the G-OSNR deteriorates. Therefore, in order to determine the worst value, the frequency with the highest gain can be set to the frequency f4.

<Other Embodiments>
The measuring device of each of the above embodiments generates an optical signal having frequencies f1, f2 and f3 = f1 + f2-f4, and measures the power of the optical signal having a frequency f4 generated by unreduced four-wave mixing. Therefore, even if other optical signals are present at frequencies other than these four optical signals, the measurement is not affected. This situation is shown in FIG. FIG. 6 shows a state in which measurement is performed using an empty band of an optical signal (communication optical signal) used in actual communication. As described above, the measuring device of each of the above embodiments can measure not only the optical communication system not used for providing the communication service but also the optical communication system used for providing the communication service. In other words, the measuring device of each of the above embodiments can measure both out of service and in service.

Further, the measuring device according to the present invention can be realized by a program that operates and functions the computer as the measuring device. These computer programs are stored in a computer-readable storage medium or can be distributed over a network.

11-13: Light source unit 2: Multiplex unit 3: Optical power measurement unit 4: Calculation unit

Claims (15)

An output means that generates optical signals of the first frequency, the second frequency, and the third frequency and outputs them to the optical transmission line to be measured.
A measuring means for measuring the power of a fourth frequency optical signal generated in the optical transmission line by mixing four light waves of the first frequency, the second frequency, and the third frequency optical signal output by the optical transmission line. ,
A determination means for determining the power spectral density of nonlinear interference noise generated in the optical transmission line by multiplying the power of the optical signal of the fourth frequency by an adjustment value.
A measuring device characterized by being equipped with. It is an output means that generates optical signals of the first frequency, the second frequency, and the third frequency and outputs them to the optical transmission line to be measured, and is one of the first frequency, the second frequency, and the third frequency. The output means, wherein one optical signal is modulated modulated light and the other frequency optical signals are continuous light.
A first measuring means for measuring the power of the modulated light output from the optical transmission line, and
The modulated light output from the optical transmission line and the optical signal of the fourth frequency generated in the optical transmission line by mixing the four light waves of the optical signals of the first frequency, the second frequency, and the third frequency are combined. A conversion means that performs photoelectric conversion and outputs a first electric signal corresponding to the modulated light and a second electric signal corresponding to the optical signal of the fourth frequency.
The power of the first electric signal output by the conversion means, the second measuring means for measuring the power of the second electric signal, and the like.
The power of the modulated light is multiplied by the ratio of the power of the second electric signal to the power of the first electric signal to obtain the power of the optical signal of the fourth frequency, and the power of the optical signal of the fourth frequency is obtained. A determination means for determining the power spectrum density of the nonlinear interference noise generated in the optical transmission line by multiplying the adjustment value, and
A measuring device characterized by being equipped with. The measuring device according to claim 1 or 2, wherein the third frequency is equal to a frequency obtained by subtracting the fourth frequency from the sum of the first frequency and the second frequency. Any of claims 1 to 3, wherein the intervals between two adjacent frequencies on the frequency axis of the first frequency, the second frequency, the third frequency, and the fourth frequency are the same. The measuring device according to item 1. The invention according to any one of claims 1 to 4, wherein the gain of the fourth frequency in the optical transmission line is within a predetermined range including an average value of gains over the transmission band of the optical transmission line. Measuring device. The measuring device according to any one of claims 1 to 5, wherein the gain in the optical transmission line of the fourth frequency is the maximum value of the gain over the transmission band of the optical transmission line. The determination means holds coefficient information indicating the relationship between the frequency and the adjustment coefficient.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is the value based on the adjustment coefficient of the fourth frequency indicated by the coefficient information, according to any one of claims 1 to 6. Measuring device. The determination means obtains a span number correction value based on the number of spans of the optical transmission line, and obtains a span number correction value.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is a value obtained by correcting the adjustment coefficient of the fourth frequency indicated by the coefficient information by using at least the span number correction value. The measuring device according to claim 7. The determination means obtains a span length correction value based on the average value of the span lengths of the optical transmission lines.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is a value obtained by correcting the adjustment coefficient of the fourth frequency indicated by the coefficient information by using at least the span length correction value. The measuring device according to claim 7. The determination means obtains a wavelength dispersion correction value based on the wavelength dispersion of the optical transmission line, and obtains a wavelength dispersion correction value.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is a value obtained by correcting the adjustment coefficient of the fourth frequency indicated by the coefficient information by using at least the wavelength dispersion correction value. The measuring device according to claim 7. The determination means obtains a dispersion slope correction value based on the dispersion slope of the optical transmission line and the dispersion slope of each span of the optical transmission line or the standard deviation.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is a value obtained by correcting the adjustment coefficient of the fourth frequency indicated by the coefficient information by using at least the dispersion slope correction value. The measuring device according to claim 7. The determination means holds a plurality of the coefficient information corresponding to each of the average values of the plurality of span lengths.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is the adjustment coefficient of the fourth frequency indicated by the coefficient information selected from the plurality of coefficient information based on the average value of the span lengths of the optical transmission lines. The measuring device according to claim 7, wherein the value is based on the value. The determination means holds a plurality of the coefficient information corresponding to each of the plurality of wavelength dispersions.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is a value based on the adjustment coefficient of the fourth frequency indicated by the coefficient information selected from the plurality of coefficient information based on the dispersion of the optical transmission line. The measuring device according to claim 7. The determination means holds a plurality of the coefficient information corresponding to each combination of the dispersion slope and the dispersion or standard deviation of the dispersion slope.
The adjustment value to be multiplied by the power of the optical signal of the fourth frequency is obtained from a plurality of the coefficient information based on a combination of the dispersion of the optical transmission line and the dispersion or standard deviation of the dispersion slope of each span of the optical transmission line. The measuring device according to claim 7, wherein the selected coefficient information is a value based on the adjustment coefficient of the fourth frequency. Any one of claims 1 to 14, wherein the determination means further determines the general-purpose optical signal-to-noise ratio of the optical transmission line based on the power spectral density of the nonlinear interference noise generated in the optical transmission line. The measuring device according to.

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