JPH07134079A - Instrument and method for measuring characteristic of optical fiber - Google Patents

Abstract

PURPOSE:To provide an instrument for measuring characteristics of optical fibers which measures the generating efficiency of four-photon mixed waves generated in an optical fiber and the characteristic of the optical fiber related to the mixed waves and a method for measuring characteristics of optical fibers. CONSTITUTION:An instrument for measuring characteristics of optical fibers is provided with signal light generating means 1 and 1' for generating two kinds of signal light having different wavelengths, polarized wave adjusting means 2 and 2' for adjusting the polarized waves of the two kinds of signal light, and a light synthesizing means 3 for synthesizing the adjusted two kinds of signal light and making the synthesized light incident to a fiber 4 to be measured. The instrument is also provided with an optical filter means 5 for selectively extracting four-photon mixed waves at the signal emitting end of the fiber 4 and a light power detecting means 6 for detecting the light power of the extracted four-photon mixed waves. The instrument finds the four-photon mixed wave generating efficiency of the fiber 4 from the light power of the four-photon mixed waves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the characteristics of an optical fiber, and more particularly to measuring the generation efficiency of a four-photon mixed wave generated in the optical fiber and the characteristics of the optical fiber related thereto. The present invention relates to an apparatus and method for measuring characteristics of an optical fiber.

With the advent of erbium-doped optical fiber amplifiers in recent years, transmission systems that directly amplify light have been studied. The erbium-doped optical fiber amplifier has a wide gain wavelength band, so that wavelength division multiplexing (WD)
It is possible to carry out M) and collectively amplify and relay light of each wavelength.

When a wavelength-multiplexed signal with high optical power is injected into a fiber, a nonlinear optical effect in the optical fiber becomes remarkable, and four-photon mixing in particular gives the most severe conditions to system design.

Therefore, it is necessary to develop a method of measuring the generation efficiency of a four-photon mixing wave generated in a transmission of a wavelength division multiplexed signal in an optical fiber, and to measure the characteristic of the optical fiber related thereto. There is a need for an optical fiber characteristic measuring apparatus and method capable of performing the above.

[0005]

2. Description of the Related Art At present, generally used optical fibers are made of silica. Quartz is essentially a material with very low nonlinearity. However, the non-linear optical effect appears due to the following reasons, and the transmission characteristics at the time of wavelength division multiplexing are deteriorated.

(1) Since the light wave is confined in a fine area of about 10 μm, the power density becomes very high. (2) Due to the restriction of the propagation mode in the low-loss region and the very long interaction length between the light wave and the material, various nonlinear interactions are prominent.

The nonlinear optical effect of the optical fiber that affects the wavelength division multiplexing transmission includes stimulated Brillouin scattering, mutual phase modulation, Raman scattering, four-photon mixing and the like. Reference `` IEEE J. Lightwave Technol., Vol.6, No.11, pp1750-
According to "1769", it is the four-photon mixing that gives the most severe condition in system design among the above-mentioned nonlinear optical effects.

That is, the four-photon mixed wave newly generated by the optical frequency mixing between the signal light waves by the four-photon mixing becomes crosstalk of the original signal light waves, and deteriorates the transmission characteristics. The generation efficiency of this four-photon mixed wave is determined by the amount of phase mismatch Δβ between the light waves, and the amount of phase mismatch Δ
β depends on the wavelength interval between light waves and the dispersion of the optical fiber.
Therefore, the zero-dispersion region of the fiber is moved to the 1.5 μm band where the transmission loss is minimized.
When F) is used as the transmission line, the effect of four-photon mixing becomes significant.

FIG. 10 shows four optical signals depending on the dispersion value of an optical fiber.
This shows the difference in the generation efficiency of the child mixed wave. DSF
Optical fiber pump light wavelength λ₁ Variance value for
Dλ ₁ When (ps / nm / km) is used as a parameter
, The wavelength interval Δλ between the pump light wavelength and the probe light wavelength_S
Four-photon mixed wave generation efficiency η (dB) corresponding to (nm)
Fig. 4 shows an example of the calculation result of
The case of 70 km and input power = + 3 dBm is illustrated.
It In the figure, SMF has a zero-dispersion range of 1.3μ.
Shows m-band single mode fiber, for control
It is shown in.

As described above, since the transmission at the wavelength whose dispersion value is close to zero is greatly affected by the crosstalk, it is necessary to reduce the incident power to the optical fiber, which greatly restricts the transmission characteristics. Will receive.

In reality, it is considered that the dispersion value changes in the longitudinal direction of the optical fiber due to the variation in the manufacturing conditions of the optical fiber, and the theoretical calculation alone shows the generation efficiency of the four-photon mixed wave. Difficult to grasp.

Therefore, if the generation efficiency of the four-photon mixed wave in the optical fiber can be measured, it will be useful information in the design of the wavelength division multiplexing transmission system. For example, in an existing optical fiber, the transmission of wavelength-multiplexed light is not considered, and the four-photon mixed wave generation efficiency is unknown.

When the WDM transmission system is introduced into such a line, if the generation efficiency distribution of the four-photon mixing wave can be measured, the transmission light wave in the section where the generation efficiency of the four-photon mixing wave becomes high is changed to another wavelength. It is possible to obtain powerful information for determining the wavelength that can be transmitted, such as changing to.

[0014]

However, the problem of crosstalk of four-photon mixed waves during wavelength-division multiplexed lightwave transmission is
This is a new problem, and a method for measuring the magnitude of a four-photon mixing wave has not been heretofore proposed.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art, and it is an apparatus for measuring a four-photon mixed wave generated in wavelength-multiplexed optical transmission and a characteristic measurement of an optical fiber related thereto. An optical fiber characteristic measuring apparatus and method for performing the above are proposed.

[0016]

[Means for Solving the Problems]

(1) FIG. 1 shows the basic configuration of the present invention. The present invention relates to a signal light generating means for generating two-wave signal light having different wavelengths, a polarization adjusting means for adjusting the polarization of the two-wave signal light, and a two-wave signal with the adjusted polarization. The light combining means for combining light to enter the measured fiber, the optical filter means for selectively extracting the four-photon mixed wave at the signal emission end of the measured fiber, and the optical power of the extracted four-photon mixed wave An optical power detection means for detecting the four-photon mixed wave is generated, and the generation efficiency of the four-photon mixed wave in the measured fiber is obtained from the optical power of the four-photon mixed wave.

(2) Using the apparatus described in (1), the four-photon mixed wave generation efficiency of the measured fiber is measured from both ends of the measured fiber.

(3) The present invention also provides a signal light generating means for generating two-wave signal light having different wavelengths, a polarization adjusting means for adjusting the polarization of the two-wave signal light, and a polarization. The optical combining means for combining the two adjusted signal lights into the fiber to be measured, the reflecting end provided at the signal emitting end of the fiber to be measured, and the optical signal to be incident on the fiber to be measured. An optical switch for switching and outputting the reflected signal at the end, an optical filter means for selectively extracting the four-photon mixed wave in the output light from this optical switch, and detecting the optical power of the extracted four-photon mixed wave An optical power detecting means is provided, and the generation efficiency of the four-photon mixed wave in the measured fiber is obtained from the optical power of the four-photon mixed wave.

(4) In the case of (3), in place of the reflection end, an optical coupler for branching / coupling light between the signal emission end of the fiber under test and the two ports, and one of the optical coupler An optical amplifier that amplifies the branched light of the port and inputs it to the other port,
An isolator for blocking light in the opposite direction between the optical amplifier and the optical coupler is provided.

(5) In the case of (3) or (4), in place of the optical switch, an optical coupler for branching / coupling light between the signal incident end of the fiber under test and the two ports, and optical combining An isolator for blocking light in the opposite direction is provided between the output side of the means and one port of the optical coupler, and the other port of this optical coupler is connected to the optical filter means.

(6) In the device of any one of (1) to (5), the wavelength sweep is performed while keeping the wavelength interval of the two signal lights constant, and the four-photon mixed wave generation efficiency is obtained.

(7) In the device according to any one of (1) to (5), one wavelength of the two-wave signal light is fixed, and the other wavelength is swept to obtain the four-photon mixed wave generation efficiency. Ask for.

(8) From the measurement results of the four-photon mixed wave generation efficiency obtained by using the apparatus described in any one of (1) to (7), when two or more signal lights are input, By predicting the generation situation of four-photon mixed waves, the wavelength allocation suitable for wavelength division multiplexing transmission in an optical fiber is obtained.

(9) The wavelengths of the first, second, third, ... Peaks of the power of the four-photon mixed wave, which are obtained by using the apparatus described in any of (1) to (7), By reading, the slope of the dispersion value of the measured fiber with respect to the wavelength is estimated from the wavelength difference of each peak wavelength.

[0025]

FIG. 2 shows the principle of measurement of a four-photon mixed wave. Reference numeral 41 denotes a fiber to be measured, and from one side thereof,
Two-wave signal light whose polarizations are controlled to coincide with each other is incident. Reference numeral 42 denotes a pump light source, which generates pump light having a wavelength λ ₁ . Reference numeral 43 denotes a probe light source, which generates a probe light having a wavelength λ ₂ . A photodetector 44 measures the intensity of the output light from the measured fiber 41 for each wavelength.

Thus, from one side of the measured fiber,
When two signal lights whose polarizations are controlled to coincide with each other are incident, a four-photon mixed wave having a wavelength difference corresponding to the wavelength interval of the signal lights is generated on both upper and lower sides of both signal lights. The amount of four-photon mixed wave, which is a crosstalk with respect to the incident light in the fiber under measurement, can be known by cutting out each of them with a photodetector equipped with a separating means such as to measure the power.

In this case, the amount of crosstalk generated in the measured fiber corresponding to the signal wavelength can be known by performing the wavelength sweep while keeping the wavelength interval of the two signal lights constant. Further, by fixing the wavelength of one wave of the two signal waves and performing the wavelength sweep of the other one wave, the amount of crosstalk corresponding to the signal wavelength interval of the optical fiber can be known. The characteristics of the optical fiber can be known by either of the above methods.

FIGS. 3 and 4 show measurement examples (1) and (2) of the four-photon mixed wave, respectively. FIG. 3 shows a case where the length of the fiber to be measured is short, and FIG. Shows the case where the length of the measured fiber is long.

If the zero-dispersion wavelength is uniform in the longitudinal direction of the optical fiber, the generation efficiency of the four-photon mixed wave becomes maximum when the pump light wavelength matches the zero-dispersion wavelength λ _C. Figure 3
Indicates the case where the length of the fiber to be measured (DSF) is 2.2 km, the solid line indicates the calculated value, and the indicates the measured value. As shown, the measurement results are in good agreement with the results predicted by the calculation.

On the other hand, FIG. 4 shows the measured fiber (D
(SF) has a length of 60 km and an input power of 4.0 dBm. The solid line indicates the measurement point and the dotted line indicates the calculated value. As shown in the figure, when the measured fiber is long, the predicted steep peak does not appear in the measurement result, and the generation of the four-photon mixed wave is distributed over a wide wavelength range.

This means that the zero-dispersion wavelength can be regarded as substantially constant in the range of the optical fiber length of several km, but in a long optical fiber used for actual transmission, the dispersion of the zero-dispersion wavelength is taken into consideration. , Shows that it is necessary to determine the wavelength arrangement. It should be noted that it is also possible to predict the occurrence of crosstalk when two or more signal lights are incident from this measurement result.

Further, in the measurement result shown in FIG. 4, the wavelength of the power peak of the four-photon mixed wave and the wavelengths of the second, third, ... It is also possible to estimate the slope of the dispersion value of the filter under measurement with respect to the wavelength from the difference.

The generation of the four-photon mixed wave also depends on the magnitude of the signal light power, and it is considered that the region near the end of the incident fiber (for example, about ten and several km) contributes most to the generation. Therefore, in order to grasp the characteristics of the optical fiber, it is necessary to perform the same measurement from both ends of the optical fiber. In particular, in the case of an optical fiber that performs bidirectional communication or the like, measurement from both directions is important.

[0034]

FIG. 5 shows the configuration of an embodiment (1) of the present invention, in which 11, 11 ′ are laser diodes (LDs) 12, 12 for generating pump light and probe light, respectively.
Reference numeral 12 'is a driver for driving the laser diodes 11, 11', 13, 13 'is a polarization controller (PC) for adjusting the polarization of the light generated by the laser diodes 11, 11', and 14 is a polarization controller 13, An optical combiner for combining the optical outputs from 13 ', an optical amplifier 15 for amplifying the optical output of the optical combiner 14,
Reference numeral 16 is a fiber under measurement, 17 is an optical filter for extracting light of a specific wavelength from the output light of the fiber under measurement 16, 18 is an optical power detector for detecting the power of the output light of the optical filter 17, and 19 is a driver 12, 12. The wavelength of the light generated by the laser diodes 11, 11 'is controlled via
A wavelength controller for controlling the wavelength of the transmitted light of the optical filter 17,
A data processing unit 20 processes the output data of the optical power detector 18.

The drivers 12 and 12 'drive the laser diodes 11 and 11' to generate pump light and probe light, respectively, and the polarization controllers 13 and 13 'match the polarizations of the respective lights. After that, photosynthesizer 1
After being multiplexed by 4, the light is amplified by the optical amplifier 15, and then is incident on one end of the fiber 16 to be measured.

The output light from the other end of the fiber 16 to be measured is applied to the optical filter 17 to extract the light of a specific wavelength determined by the optical filter 17, and the optical power detector 18 detects the power.

At this time, the wavelength controller 19 controls the wavelength of the light generated by the laser diodes 11 and 11 ', and
By controlling the transmission wavelength of the optical filter 17 to match the wavelength of the crosstalk light, the crosstalk light is selectively input from the optical filter 17 to the optical power detector 18 and its power is measured. The data processing unit 20 obtains the four-wave mixing wave generation efficiency from the measured optical power.

At this time, it is possible to obtain the four-photon mixed wave generation efficiency in the case where the wavelength intervals are constant by gradually changing the wavelengths of the light generated by the laser diodes 11 and 11 'while maintaining the same wavelength intervals. Also, by fixing one wavelength of the signal light and changing the other wavelength,
It is possible to obtain the four-photon mixed wave generation efficiency when the wavelength interval changes.

FIG. 6 shows a concrete example of the configuration of the present invention. Reference numerals 21 and 22 denote wavelength tunable laser diodes (LDs), the wavelength of the generated light of which is controlled by the controller 23. Pump light and probe light are generated respectively. Reference numeral 24 denotes a polarization controller (PC), which is inserted in one output of both wavelength tunable laser diodes and makes the polarization of the output light of both wavelength tunable laser diodes 21 and 22 coincident with each other. An optical coupler 25 synthesizes the outputs of the wavelength tunable laser diodes 21 and 22 and outputs the combined output.

An optical amplifier 26 amplifies the combined light from the optical coupler 25 and inputs it to the fiber under test 27. An optical spectrum analyzer 28 separates each component light from the output light of the fiber 27 to be measured and detects each optical power. A data processing unit 29 obtains the four-photon mixed wave generation efficiency from the output light wavelength data of both wavelength tunable laser diodes from the controller 23 and the power of each component light from the optical spectrum analyzer 28.

FIG. 7 shows the configuration of the embodiment (2) of the present invention, in which the same components as in FIG. 5 are designated by the same reference numerals, and 31 denotes an optical signal incident on the fiber 16 to be measured. At the same time, an optical switch for switching and outputting an optical signal in the opposite direction at the incident end, 32 is an optical coupler for branching / coupling light between the signal emitting end of the measured fiber 16 and the two ports, and 33 is , An optical amplifier for amplifying the branched light of one port of the optical coupler 32 and inputting it to the other port,
Further, 34 is an isolator that blocks light in the opposite direction between the optical amplifier 33 and the optical coupler 32.

The optical output from the fiber 16 to be measured is amplified by the optical amplifier 33 via the optical coupler 32, and is then output again through the optical coupler 32 in the reverse direction on the fiber 16 to be measured. At this time, the isolator 34 functions to prevent output from the optical coupler 32 to the optical amplifier 33 side in the opposite direction.

The optical switch 31 sets the optical output from the optical amplifier 15 at the timing when the optical output is generated.
The output timing of the optical output from the fiber 16 to be measured is switched so as to pass the optical output to the optical filter 17 side.

Therefore, according to the embodiment shown in FIG.
The measured fiber 16 has already been laid,
Even when the input end and the output end are remote from each other, the four-photon mixed wave generation efficiency can be measured as in the embodiment shown in FIG.

FIG. 8 shows a modification of the embodiment (2), in which the same parts as those in FIG. 7 are indicated by the same numbers, and 35 is the signal incident end of the fiber 16 to be measured and two ports. An optical coupler for branching / coupling light between
Is an isolator that blocks light in the opposite direction between the output side of the optical amplifier 15 and one port of the optical coupler 35. The other port of the optical coupler 35 is connected to the optical filter 17
Connected to.

The optical coupler 35 transmits the signal from the optical amplifier 15 to the side of the fiber under test 16, and the fiber under test 1
The signal from 6 is transmitted to the optical filter 17 side. At this time, the isolator 36 moves from the optical coupler 35 to the optical amplifier 1
It acts to prevent output in the opposite direction to the 5 side.

In this way, the optical switch 31 can be replaced by a combination of an optical isolator and an optical coupler. In this case, it is not necessary to control the timing between the input from the light source side to the fiber 16 to be measured and the output to the detector side.

FIG. 9 shows the configuration of the embodiment (3) of the present invention. The same components as those in FIG. 7 are designated by the same reference numerals, and 37 is provided at the other end of the fiber 16 to be measured. A reflecting end, 38 is an optical modulator that AM-modulates one signal light in accordance with a signal from an oscillator 39, and 40 is an optical power detector 18.
Is a lock-in amplifier for synchronously detecting the output of the above-mentioned using the signal of the oscillator 39.

The light output from the fiber 16 to be measured is reflected by the reflection end 37 and is again output to the fiber 16 to be measured in the opposite direction. The optical switch 31, as in the case of the embodiment shown in FIG. When the optical output of 1 is generated, switching is performed so as to pass it to the optical filter 17 side, and the reflected component is detected by the optical power detector 18 via the optical filter 17.

At this time, the output of one laser diode 11 'is AM-modulated by the signal from the oscillator 39 in the optical modulator 38. Therefore, since the wavelength component based on the output of the laser diode 11 'and the crosstalk component in the reflection component detected by the optical power detector 18 are modulated, the lock-in amplifier 40 outputs the signal from the oscillator 39. By performing synchronous detection using, it is possible to detect separately. The data processing unit 20 determines the four-photon mixed wave generation efficiency based on these detected values.

In the embodiment shown in FIG. 8, since the optical amplifier is not used at the reflection end, the level of the signal corresponding to the four-photon mixing wave detected by the optical power detector is small, but the lock-in is performed. By performing synchronous detection using an amplifier, this can be detected with high sensitivity, and the four-photon mixed wave generation efficiency can be obtained.

Also in the case of the embodiment shown in FIG. 9, the optical switch 31 can be replaced by a combination of an optical coupler and an isolator as in the case of FIG.

As described above, with the optical fiber characteristic measuring apparatus and method of the present invention, it is possible to obtain the cumulative total amount of the four-photon mixed wave power at the exit end, in a state in which the variation of the optical fiber is included. Therefore, the present invention is effective in determining whether or not the wavelength division multiplex transmission system can be applied to an already installed optical fiber, or in selecting a signal light wavelength that can be transmitted. .

Furthermore, from the measurement results of the four-photon mixed wave generation efficiency obtained by using the measuring apparatus of the present invention, it is possible to predict the generation state of the four-photon mixed wave when two or more signal lights are input. This makes it possible to obtain the optimum wavelength arrangement suitable for transmission in wavelength division multiplexing communication.

Further, by reading the wavelength of the peak of the power of the four-photon mixed wave from the measurement result of the four-photon mixed wave generation efficiency obtained by using the measuring apparatus of the present invention, the wavelength difference between the respective peak wavelengths is read. From the four-photon mixed wave generation efficiency,
It is possible to estimate the slope of the dispersion value of the measured fiber with respect to the wavelength.

[0056]

As described above, according to the present invention, it is possible to measure the generation efficiency of a four-photon mixed wave, which is generated when a wavelength-multiplexed signal is transmitted in a fiber to be measured. Since it is possible to measure the characteristics of the optical fiber related to the above, it is possible to obtain powerful information in the design of the wavelength division multiplexing transmission system.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a principle of measuring a four-photon mixed wave.

FIG. 3 is a diagram showing a measurement example (1) of a four-photon mixed wave.

FIG. 4 is a diagram showing a measurement example (2) of a four-photon mixed wave.

FIG. 5 is a diagram showing a configuration of an embodiment (1) of the present invention.

FIG. 6 is a diagram showing a specific configuration example based on the embodiment (1).

FIG. 7 is a diagram showing a configuration of an embodiment (2) of the present invention.

FIG. 8 is a diagram showing a modified example of the embodiment (2).

FIG. 9 is a diagram showing a configuration of an embodiment (3) of the present invention.

FIG. 10 is a diagram showing a difference in generation efficiency of a four-photon mixing wave depending on dispersion values of optical fibers.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal light generating means 1'Signal light generating means 2 Polarization adjusting means 2'Polarization adjusting means 3 Optical combining means 4 Fiber under test 5 Optical filter means 6 Optical power detecting means 31 Optical switch 32 Optical coupler 33 Optical amplifier 34 Isolator 35 Optical coupler 36 Isolator 37 Reflection end

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Kuwahara 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (9)

[Claims] 1. Signal light generating means (1, 1 ') for generating two-wave signal light having different wavelengths, and polarization adjusting means (2, 2) for adjusting the polarization of the two-wave signal light.
2 '), the optical combining means (3) for combining the two polarized signal-adjusted signal lights and entering the measured fiber (4), and the signal emitting end of the measured fiber (4). An optical filter means (5) for selectively extracting a four-photon mixed wave and an optical power detection means (6) for detecting the optical power of the extracted four-photon mixed wave are provided, and the light of the four-photon mixed wave is provided. A device for measuring characteristics of an optical fiber, characterized in that the generation efficiency of a four-photon mixed wave in the measured fiber (4) is obtained from the power. 2. The optical fiber characteristic measuring device according to claim 1, wherein the four-photon mixed wave generation efficiency of the measured fiber (4) is measured from both ends of the measured fiber (4). Measuring method of optical fiber characteristics. 3. A signal light generating means (1, 1 ') for generating two-wave signal light having different wavelengths, and a polarization adjusting means (2, 2) for adjusting the polarization of the two-wave signal light.
2 ′), an optical combining means (3) for combining the two polarization-adjusted signal lights and making them incident on the measured fiber (4), and a signal emission end of the measured fiber (4). A reflection end (37) provided, an optical switch (31) for injecting an optical signal into the measured fiber (4) and switching and outputting a reflection signal at the incident end, and an optical switch (31) from the optical switch (31) An optical filter means (5) for selectively extracting the four-photon mixed wave in the output light and an optical power detection means (6) for detecting the optical power of the extracted four-photon mixed wave are provided. An apparatus for measuring characteristics of an optical fiber, characterized in that a four-photon mixed wave generation efficiency in the measured fiber (4) is obtained from the optical power of the mixed wave. 4. An optical coupler (32) for branching / coupling light between the signal emitting end of the fiber under test (4) and two ports, instead of the reflecting end (37), and the optical coupler (32). An optical amplifier (33) for amplifying the branched light of one port of the coupler (32) and inputting it to the other port, and the optical amplifier (33)
The optical fiber characteristic measuring device according to claim 3, further comprising an isolator (34) for blocking light in the opposite direction between the optical coupler and the optical coupler (32). 5. An optical coupler (35) for branching / coupling light between a signal incident end of the fiber under test (4) and two ports instead of the optical switch (31), and the optical combining. An isolator (36) for blocking light in the opposite direction between the output side of the means (3) and one port of the optical coupler (35) is provided and the other port of the optical coupler (35) is The optical fiber characteristic measuring device according to claim 3 or 4, which is connected to an optical filter means (5). 6. The optical fiber characteristic measuring device according to claim 1, wherein the four-photon mixed wave generation efficiency is achieved by performing wavelength sweeping while keeping a constant wavelength interval between the two signal lights. A method for measuring characteristics of an optical fiber, characterized in that 7. The optical fiber characteristic measuring device according to claim 1, wherein one wavelength of the two-wave signal light is fixed and the other wavelength is swept to obtain the four-wave signal light. A method for measuring characteristics of an optical fiber, characterized in that a generation efficiency of a photon mixed wave is obtained. 8. The optical fiber characteristic measuring device according to any one of claims 1 to 7, wherein when four or more signal lights are input from the obtained measurement result of the four-photon mixed wave generation efficiency. A method for measuring the characteristics of an optical fiber, which comprises predicting the generation state of a photon mixed wave and determining a wavelength arrangement suitable for wavelength division multiplexing transmission in the optical fiber. 9. The optical fiber characteristic measuring device according to claim 1, wherein the wavelengths of the first, second, third, ... Peaks of the power of the four-photon mixed wave obtained are read. A method for measuring characteristics of an optical fiber, which comprises estimating a slope of a dispersion value of a measured fiber with respect to a wavelength from a wavelength difference between respective peak wavelengths.