JPH10115573A - Method and apparatus for measurement of tertiary nonlinear susceptibility rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which the tertiary nonlinear susceptibility rate of a powder sample or a film sample is measured and to provide its apparatus. SOLUTION: A rotating base 41 is turned, and a photodiode 40 is retreated to a position which is not disturbing. In succession, a shutter 3 is opened, and a sample is irradiated with a beam 32 and a beam 33. The angle of incidence of the beam 33 is set to be smaller than a total-reflection critical angle. A rotating base 10 is turned, an angle is swept at about 62 deg.C, and an angle at which a signal intensity becomes strongest is searched. At this time, the magnitude of the angle of incidence of a beam 31 is made just equal to that of the angle of incidence of the beam 32m the angle of the rotating base at this time is read out, and a precise angle of incidence is found. On the basis of the angle, a tertiary nonlinear susceptibility rate is found by a computer 16. Consequently, the tertiary nonlinear susceptibility rate of a powder sample or a nonhomogeneous film sample which is hard to measure can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to optical communication, optical computers, optical recording, optical measurement, etc. through devices such as wavelength conversion of light, generation of phase conjugate light, optical switches, and optical bistables. The present invention relates to a method and an apparatus for evaluating a nonlinear optical material, or a Raman spectrometer which is an analyzer for a chemical substance, a biological substance and the like.

[0002]

2. Description of the Related Art The third-order nonlinear susceptibility is a function of the frequency and time of the four lights involved, and is an important physical quantity in quantifying the magnitude of various nonlinear optical phenomena. Conventionally,
As a method for measuring the third-order nonlinear susceptibility, a third-order harmonic generation method, a degenerate four-wave mixing method, a coherent Raman measurement method, and the like are known. For these methods, for example,
Shen, Principles of Nonlinear Optics, John Wiley and Sons, 1984, pp. 242-285 (YR Shen, The Principles of Nonlinear Optic)
s, (John Wiley & Sons, Inc, 1984) pp. 242-285)
And various textbooks. However, since the third-order nonlinear susceptibility involved in each nonlinear phenomenon is different, the susceptibility obtained by each method is different. Of these, the degenerate four-wave mixing method is involved in phenomena that can be applied to optical switches and optical arithmetic, and it is important to investigate the efficiency of this in material development. Also, the point that the measurement wavelength can be selected relatively freely,
By performing time-resolved measurement, a characteristic feature is that much information can be obtained because the relaxation process of the excited state can be examined. Raman measurement is widely used to investigate the similarity and chemical bonding state of a substance. By measuring a component having a third-order nonlinear susceptibility, a Raman spectrum can be obtained. Method or nonlinear Raman method.

[0003]

In the conventional degenerate four-wave mixing method, non-degenerate four-wave mixing method, coherent Raman measurement method, etc., accurate measurements can be compared for gas, solution samples, single crystal samples, and thin film samples. Although it can be easily achieved, it is difficult to apply this method when a high-quality single crystal or thin film sample cannot be obtained.

An object of the present invention is to perform degenerate four-wave mixing, non-degenerate four-wave mixing, and coherent Raman measurement on a material from which a single crystal or a thin film sample cannot be obtained or is difficult to manufacture, and which is involved in each of them. It is an object of the present invention to provide a measurement method capable of obtaining a non-linear susceptibility or a spectrum thereof and an apparatus for realizing the same.

[0005]

Generally, even if a large single crystal cannot be obtained, a powder microcrystal sample can be easily prepared. When a powder sample is used, the conventional method has a problem of scattering of light due to agglomerates. The same applies to non-uniform film samples. In order to suppress this, the sample may be brought into close contact with the prism or the substrate, light may be incident from the prism or the substrate side, and may be totally reflected at the interface. At this time, evanescent light enters the sample side, and light generated by the third-order nonlinear effect caused by the evanescent light may be detected as signal light.

When the evanescent light penetration length is shorter than the sample particle size, light scattering by the sample can be suppressed.
At this time, all of the three incident lights may be evanescent. However, since the signal light is generated only from a portion where the three lights overlap, if the arrangement is such that the incident angle and the polarization are different and can be distinguished, It is enough to make one of them evanescent. At this time, the interface between the sample and the prism or the substrate needs to have flatness such that the unevenness is sufficiently small compared to the penetration length of the evanescent light. This is achieved by strongly pressing the powder sample against the prism or the substrate. Can be achieved.

[0007] This method is also useful for membrane samples. When a film is formed on a substrate, a portion in contact with the substrate can be relatively easily formed into a uniform film, but the side in contact with air is often not flat, and scattering of this portion becomes a problem. According to this method, since the evanescent light exists only near the substrate interface, a signal is generated only from a homogeneous portion, so that this problem can be solved. Furthermore,
Since the penetration length of the evanescent light can be adjusted by changing the incident angle, it is possible to measure the distribution of the third-order nonlinear susceptibility in the thickness direction.

[0008] The nonlinear susceptibility is a tensor. In the case of a powder sample, since the respective powder crystals present in the light-irradiated part are oriented in different directions, the spatially averaged nonlinear susceptibility tensor is used as the signal. Involved in. However, in the case of an alignment film sample, it is possible to obtain a tensor component. To this end, it is sufficient to change the polarization of the three incident lights and check the polarization of the signal light and its intensity.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the case of degenerate four-wave mixing, one laser beam may be split into three, so that a simple and inexpensive device configuration can be realized. Since this is the most basic configuration, the method of the present invention in this case will be described in detail with reference to FIG. FIG. 1 shows an interface between a prism having a refractive index of np and a sample having a refractive index of ns. The signal light of four-wave mixing is emitted in a direction in which phase matching can be obtained. If the k vectors of the two lights are made to face each other and another light is made incident on the two vectors at a certain angle, the signal light propagates in the opposite direction on the axis of the third light. At this time, the two lights may be evanescent lights. That is, as shown in FIG.
And two beams of beam 2 are incident at incident angles t1 and -t1, when t1 is greater than the critical angle for total reflection, the two lights are totally reflected and the two evanescent lights face each other along the interface. To propagate. At this time, the wave vector ke is represented by the following (Equation 1), where λ is the light wavelength.

[0010]

(Equation 1)

In the case of degenerate four-wave mixing, since the wavelengths are the same, if two lights are incident on the prism at the same incident angle (however, the signs are different) and are totally reflected, the opposite light of the same size is obtained. Evanescent light having the following wave number vectors k1 and k2. Here, when the third light 3 is incident at an incident angle t3, the signal light s is emitted in the direction of t3. Actually, there is a direction in which phase matching can be obtained on the sample side,
When a powder sample is used, the scattering of other light is large,
Since it is difficult to observe this separately, it is better to observe the signal light emitted to the prism side. This is not the case with a high-quality film sample or the like. In the arrangement shown in FIG. 1, a beam 2 diffracted by the interference fringes of the refractive index generated in the sample by the beams 1 and 3 is observed as signal light. Since the beams 1 and 2 are evanescent light, their wave vectors are parallel to the interface between the prism and the sample as described above.
No diffraction occurs unless incident at an angle other than degrees. Therefore, since beam 3 must not be evanescent light, t 3
3 needs to be smaller than the critical angle for total reflection. However,
In other arrangements, such as the case of Example 4 described later, it may be better to totally reflect all light.

Also, by changing the wavelength of the incident light, non-degenerate four-wave mixing is achieved, and the wavelength characteristics of the third-order nonlinear susceptibility can be measured. In this case, the direction in which the signal light is emitted is
Since this is a direction in which phase matching can be obtained and can be easily calculated based on the incident angle and the wavelength, a light receiving system may be arranged at that position.

As a special case, if the wavelengths of the two lights are made the same and the wavelength of the other light is swept, the signal intensity increases or the polarization changes when the wavelength difference resonates with the vibration energy of the sample. There is a phenomenon. These are coherent traman and are used for measurement of Raman spectrum. The method of the present invention can also measure Raman spectrum and is effective for measurement of powder sample and distribution of film sample in the thickness direction.

An apparatus for realizing the method of the present invention requires a high refractive index prism for generating total reflection and a mechanism for bringing a sample into close contact with the prism.

For the prism, a material having a higher refractive index than the sample at the wavelength of the light to be totally reflected and transparent at all the light wavelengths involved is selected. The prism should be hemispherical or semi-cylindrical, and if the light is allowed to pass through the center, the angle of incidence will not change due to refraction and the irradiation position of the sample will not change. Useful for changing. In order to make the powder sample adhere to the prism, the powder is placed in a cell with a hole, and one side is pressed against the prism with a screw. At this time, by adjusting the torque applied to the screw, the degree of pressing can be controlled, and the reproducibility of the result can be improved. In the case of a film sample, it may be applied directly to the prism, or the substrate may be used instead of the prism.

The incident light may be airborne light,
It is more convenient to control the incident angle by guiding the light to just before the prism using an optical fiber, and the apparatus can be made compact. In order to determine the tensor component of the nonlinear susceptibility, the polarization of each incident light may be controlled and the polarization analysis of the signal light may be performed. This can be achieved by combining a normal method using a wave plate, a polarizer, and an analyzer.

In order to measure the wavelength characteristics of the non-linear susceptibility by non-degenerate four-wave mixing, three wavelength-variable lasers are prepared because three incident lights need to be variable in wavelength. In order to obtain a Raman spectrum, two out of three incident lights may have the same wavelength, so that only two lasers are required, but at least one needs to be tunable. In the case of degenerate four-wave mixing, one laser is required, but if this is tunable, the chromatic dispersion of the nonlinear susceptibility that contributes to degenerate four-wave mixing can be measured.

Further, the non-linear susceptibility is a function of time,
In the absorption region, it is determined by the lifetime of the excited state, the diffusion speed of the carrier, and the like. Measuring these is not only physically meaningful, but also important because it contributes to the response speed when applied to actual devices. In order to measure this, the signal light may be time-resolved and analyzed using at least one of the three incident lights as a pulse laser. An electrical method such as an oscilloscope or a boxcar integrator may be used, and for a faster response, an optical delay method may be used.

An important point of the present invention is that at least one light is totally reflected. Therefore, it is important as well as convenient to be able to measure the total reflection critical angle simultaneously. By measuring the reflectance while changing the incident angle, the critical angle of total reflection can be known. The refractive index of the sample can be determined from the refractive index of the prism and the critical angle for total reflection. Since the device configuration for this measurement and the measurement of the nonlinear susceptibility are almost the same, this can be realized by adding a photodetector, and automation is easy. Since the excitation laser beam can be used as it is, there is an effect that the same measurement portion of the sample can be measured in the same state as when measuring the third-order nonlinear susceptibility.

(Embodiment 1) Measurement by degenerate four-wave mixing which is a typical embodiment of the present invention will be described with reference to FIG. As the excitation laser 1, a Q-switched Nd: YAG laser was used. The emitted light is split into three light beams by the beam splitters 21 and 22. At this time, the reflectivity of the beam splitter was set to 40% and 30% at 21 and 22, respectively. The split light is guided by the mirror 4 and enters the rutile prism 6 through the lens 20. The rutile prism has a semi-cylindrical shape and is processed so that the c-axis is perpendicular to the paper surface. A wave plate 5 is arranged to adjust the polarization of each light beam. A sample 8 placed in a sample cell 7 is pressed against the prism 6 by screws 9. At this time, the torque value of the screw was 2 kgfcm. The components 6 to 9 are arranged on the turntable 10 such that the center of the bottom of the prism coincides with the central axis. The generated signal light 34 is received by the photomultiplier 14 by the 50% -reflecting beam splitter 12 and integrated by the boxcar integrator 15. In front of the photomultiplier tube, an analyzer 13 for analyzing the polarization and a filter 18 for adjusting the light quantity are provided.
Is inserted. The data integrated by the boxcar integrator 15 is sent to a computer 16 for analysis. In order to measure the critical angle for total reflection, a photo diode 40 is arranged on a turntable 41. The driver 11 for driving the turntables 10 and 41 is also controlled by the computer 16. In this embodiment, the case where all the light is s-polarized light will be described for simplicity.

Hereinafter, the procedure for preparing the apparatus will be described. The refractive index of the rutile prism at the oscillation wavelength of 1064 nm of the Nd: YAG laser is 2.74 for s-polarized light. The critical angle for total reflection depends on the refractive index of the sample, but is 61.2 degrees for a refractive index of 2.4. In the transparent region, since the refractive index of most substances is smaller than this, if the incident angle is made larger, the condition of total reflection can be satisfied. Further, as shown in FIG. 3, when the incident angle is increased to such an extent, the penetration length of the evanescent light is not so close to the refractive index of the sample.
Here, the incident angles of the beams 31 and 32 are approximately 6 respectively.
The optical arrangement is determined geometrically to be 2 degrees and -62 degrees. Thereafter, the shutter 3 is closed, beams other than the beam 31 are shielded, and the turntable 10 is rotated to return the beam 31 reflected from the bottom surface of the prism 6 to the aperture 17. At this time, the beam 31 is perpendicularly incident on the prism bottom surface. The reading angle of the turntable at this time is set to the reference value 0.

Here, a method of measuring the critical angle of total reflection will be described. By rotating the turntable 10 and changing the angle of incidence of the beam 31, the turntable 41 is turned to bring the photodiode 40 to the reflection position, and the reflected light intensity is measured, as shown in FIG. FIG. 4 shows the measurement results with the powdered quartz, and the solid line is obtained by parameter fitting using the following (Equation 2).

[0023]

(Equation 2)

From this, the critical angle of total reflection can be determined, and the refractive index of the sample can be determined. Although not shown in FIG. 2, a filter for adjusting light intensity is inserted in front of the photodiode 40.

Next, the procedure for measuring the third-order nonlinear susceptibility will be described. First, the turntable 41 is turned to retract the photodiode 40 to a position where it does not interfere, for example, the 3 o'clock position in FIG. Subsequently, the shutter 3 is opened, and the beams 32 and 33 are irradiated on the sample. Beam 33
Is smaller than the critical angle for total reflection. Turntable 10
Is rotated to sweep the angle in the vicinity of 62 degrees to search for an angle at which the signal intensity is the strongest. Since this time is when the incident angles of the beams 31 and 32 are just equal, the angle of the turntable at this time can be read to find the exact incident angle. These operations, including the critical angle of total reflection measurement, are automated by the computer 16.

FIG. 5 shows the results of measurements on a phthalocyanine powder as a sample. The horizontal axis indicates the reading angle of the turntable, and the vertical axis indicates the signal light intensity. At an incident angle of 62.8 degrees, phase matching is achieved and a peak is observed. The light intensity that is not 0 even at other angles is reflected light from the incident surface of the prism, reflected light from the wave plate, and noise in the electrical system. By subtracting this, the peak height is measured and compared with a standard sample to determine the third-order nonlinear susceptibility.

As the laser 1, a dye laser, a semiconductor laser, a titanium sapphire laser, a color center laser,
If a tunable laser such as an optical parametric oscillator is used, the chromatic dispersion of the third-order nonlinear susceptibility can be obtained. When the wavelength is changed, the refractive index between the prism and the sample is different, and the evanescent light penetration length is also changed. This is corrected by a computer at the time of analysis. Beam 3
2 from another laser source and beams 31 and 3
By making 3 a wavelength variable, it becomes possible to measure a third-order nonlinear susceptibility involving two wavelengths. This is useful for Raman spectrum measurement and material evaluation that can be applied to an element in which certain light switches light of another wavelength.

Here, the laser light is propagated in the air,
If the optical fiber is used for guiding, the device becomes compact and the handling becomes easy.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIG. The device configuration is almost the same as that of FIG. 2, except that the beams 231 and 232 are
Guided using 202. Optical fibers 201, 202
Is equipped with a lens at the tip and is adjusted so that the beam becomes parallel light in the prism. When the intensity of the laser beam is weak or the nonlinearity of the sample is small, adjustment may be made so that the beam is focused on the surface of the sample. These tips are fixed on the two rotating tables 211 and 212 so that the incident angle can be adjusted independently. The rotation axes of the rotary tables 211 and 212 are coaxial with the rotary tables 10 and 41. The lengths of the fibers 201 and 212 were adjusted so that the optical path lengths of the beams 231 and 232 were the same. Here, since the length of the fiber is short, a normal fiber is used. However, if a polarization-maintaining fiber is used, more accurate polarization analysis measurement can be performed.

The structure of the first embodiment has the effect of reducing the number of movable parts and the number of parts, but it is difficult to change the incident angle of the beam. Therefore, since the penetration length of the evanescent light changes depending on the refractive index of the sample or the wavelength of the laser, the accuracy of the result is deteriorated. In the case of the device configuration of the present embodiment, the incident angles of the beams 231 and 232 can be changed, so that the beam 231 and the beam 232 can always be adjusted to have the same penetration length. Alternatively, in the case of a sample having a small nonlinear susceptibility, a large signal intensity can be obtained by reducing the incident angle of the beams 231 and 232 to increase the penetration length of the evanescent light. Can be improved. Further, since the penetration length of the evanescent light can be changed, it is possible to measure the profile of the nonlinear susceptibility in the depth direction of the sample. Further, when the wavelengths of the three lights are changed to obtain the wavelength characteristic of the nonlinear susceptibility, the incident angle of the beam 3 can be similarly adjusted using a fiber so that the incident angles of the three beams are changed. By independent adjustment, the direction in which the signal light is emitted can always be in the direction of the photodetector. These angles of incidence can be easily calculated from the phase matching conditions and the turntable is computer controlled,
Automatically adjustable.

(Embodiment 3) An embodiment in which the present invention is applied to time-resolved measurement will be described with reference to FIG. The apparatus configuration is almost the same as that of FIG. 2, and a dye laser 301 excited by a mode-locked YAG laser 300 having a pulse width of 10 ps was used as an excitation laser. In the case of the Q-switched Nd: YAG laser, the pulse width was 10 ns, which was equivalent to 3 m in terms of distance, so that it was easy to temporally overlap three light pulses on the sample surface. However, in the case of 10 ps, since there is only 3 mm, the optical delay paths 311, 312, and 313 are used to equalize the optical path lengths of the three lights. When the turntable 10 is set to a position where phase matching can be obtained just as in the first embodiment, any one of the delay times is changed, and a change in the signal due to the change is measured. it can. Here, the configuration of the first embodiment is used, but a configuration similar to that of the second embodiment may be used. Further, by using a femtosecond laser, measurement with higher time resolution is possible. Conversely, if a slower phenomenon is observed, the time change of the signal can be measured using an electrical method such as an oscilloscope or a boxcar integrator. In this case, the beam 331 is continuous light. FIG. 8 shows the time characteristic of the third-order nonlinear susceptibility of the phthalocyanine vapor-deposited film measured with the configuration of FIG. 7 by oscillating a laser beam of 600 nm using rhodamine 6G as the laser dye.

(Embodiment 4) An embodiment in which the present invention is applied to a Raman spectrometer will be described with reference to FIG. Here, a continuous-wave dye laser 401 with a frequency ω1 of argon laser excitation and a nanosecond pulse dye laser 402 with a frequency ω2 of nitrogen laser excitation were used. Two lights 431 and 4
32 is made to enter the prism as shown in the figure. In this case, there are only two beams, but beam 432 serves as two lights. Here, both beams are totally reflected so that the overlap of light in the sample becomes the largest. The light receiver 404 is placed at the position of regular reflection of the beam 431, and measures the intensity. A silicon photodiode was used as the light receiver 404. An aperture 403 and a bandpass filter 405 of ω1 are placed in front of the light receiver 404 to eliminate scattering of light of ω2. When the wavelength of the dye laser 402 is swept, the intensity of the beam 431 increases when the Raman frequency of the sample matches 2 × ω2−ω1. Beam 40
Since 2 is a pulse, the signal is also a pulse. The leading value of this pulse is measured using a sampling oscilloscope. This is a so-called Raman gain spectrum.
Similarly, an inverse Raman loss spectrum can be taken.

Since the wavelength of the laser 401 is also variable here, an appropriate ω1 can be selected depending on the sample. However, this laser does not have to be variable in order to obtain an inexpensive device. Although a continuous wave laser and a pulsed laser are used, a method of using both as a continuous wave laser or a method of using both as a pulsed laser is also known, and the method of the present invention can be similarly applied. Further, in the present embodiment, the beam 432 is guided by using the optical fiber 201. However, if the beam 431 and its reflected light, that is, signal light are similarly guided by using an optical fiber, the device becomes more compact and easy to use.

In this embodiment, the arrangement of the apparatus for the Raman gain method is used. Coherent Raman spectroscopy can also be performed.

[0035]

According to the present invention, it is possible to easily measure the third-order nonlinear susceptibility of a sample which has been impossible or difficult to measure, for example, a powder sample or a film sample in which it is difficult to produce a uniform film quality. It becomes possible. Unlike single crystals or good quality film samples,
Since such a sample can be easily prepared, a large number of materials and materials synthesized systematically can be evaluated. As a result, the speed of material development is dramatically increased, and a guideline for material design can be found.

In the case of a material such as a complex or a salt in which nonlinearity is increased by charge transfer between molecules, the electronic state greatly differs between a solution and a solid state, and it is meaningless to measure the third-order nonlinear susceptibility using a solution. Therefore, it is important to measure in the solid state. The present invention is particularly useful for evaluating such materials.

Further, since the magnitude of the non-linear susceptibility in the depth direction of the sample can be measured, the concentration distribution of the non-linear molecules in the film can be known. Further, by using the wavelength tunable laser, the wavelength characteristic of the third-order nonlinear susceptibility can be measured,
As a special case, measurement of the Raman spectrum is also possible. Although Raman spectrum measurement of a sample with much scattering, such as the above-mentioned organic material and biological sample, has been difficult, the present invention makes it possible.

[Brief description of the drawings]

FIG. 1 is an alternative principle diagram of the present invention.

FIG. 2 is a configuration diagram of an apparatus for degenerate four-wave mixing.

FIG. 3 is a view showing the penetration length of evanescent light at the interface between a rutile prism (np = 2.74) and a sample having a refractive index of n.

FIG. 4 is a view showing measurement data of a critical angle of total reflection.

FIG. 5 is a diagram showing a signal example of degenerate four-wave mixing.

FIG. 6 is a configuration diagram of an apparatus for degenerate four-wave mixing using an optical fiber.

FIG. 7 is a diagram showing a device configuration of time-resolved degenerate four-wave mixing.

FIG. 8 is a diagram illustrating a signal example of time-resolved degenerate four-wave mixing.

FIG. 9 is a configuration diagram of an apparatus for Raman scattering measurement.

[Explanation of symbols]

1 ... Laser, 3 ... Shutter, 4 ... Mirror,
5. Half-wave plate, 6 ... Prism, 7 ... Sample cell,
8. Sample, 9. Screw, 10 Turntable, 11. Turntable drive circuit, 12. Beam splitter, 13 Analyzer, 14. ... receiver, 15 ... boxcar integrator,
16. Computer, 20. Lens, 21, 2
2 .... Beam splitter, 31, 32, 33 ... Laser beam, 40 ... Receiver, 41 ... Turn table, 201, 2
02 .... optical fiber, 211, 212 ... turntable, 2
31, 232: laser beam, 300: mode-locked Nd: YAG laser, 301: dye laser, 311, 31
2, 313 ... optical delay device, 401 ... argon laser excited CW dye laser, 402 ... nitrogen laser excited dye laser, 403 ... aperture, 404 ... light receiver, 40
5. Bandpass filters, 431, 432 ... laser beams.

Claims (13)

[Claims] 1. A sample to be measured is brought into close contact with a prism or a substrate, and at the time of performing four-wave mixing in the sample to be measured using three laser beams, at least one light is totally reflected in the prism or the substrate. A third-order nonlinear susceptibility measuring method for measuring the third-order nonlinear susceptibility of a sample by measuring the polarization and intensity of light generated from the sample. 2. The method according to claim 1, wherein the tensor component of the third-order nonlinear susceptibility of the sample is measured by changing the polarization directions of the three incident lights. 3. A single light source is branched into three light beams, the incident angles of the two light beams are equal to or greater than the critical angle for total reflection, the signs are the same, and the signs are the same. 3. The method for measuring a third-order nonlinear susceptibility according to claim 1, wherein degenerate four-wave mixing is performed, and signal light emitted in the opposite direction on the axis of the third light is observed. 4. Simultaneously changing the wavelength of the light source to obtain a 3
4. The method of measuring a third-order nonlinear susceptibility according to claim 3, wherein the chromatic dispersion of the second-order nonlinear susceptibility is measured. 5. The method of measuring a third-order nonlinear susceptibility according to claim 1, wherein the wavelength characteristics of the third-order nonlinear susceptibility of the sample are measured by respectively changing the wavelengths of the three incident lights. . 6. The Raman spectrum of a sample is measured by setting the wavelengths of two incident lights to be the same, and sweeping either the wavelength or the wavelength of another light. Or the third-order nonlinear susceptibility measuring method according to 2. 7. A time response characteristic of a non-linear susceptibility is measured by performing time-resolved measurement of a signal light by using at least one of the three lights as a pulse light and using an optical delay unit or an electrical method. The method of measuring a third-order nonlinear susceptibility according to any one of claims 1 to 6, wherein: 8. One to three laser light sources for obtaining three laser beams, an optical system for adjusting the polarization direction of each of the laser beams, a prism for totally reflecting the laser beams, and a sample. A third-order non-linear susceptibility measurement device comprising an optical system and a light receiver for measuring the polarization and intensity of the signal light generated from the light receiver, and an analyzer for processing and analyzing the electric signal from the light receiver. 9. A system for guiding at least one laser beam using a fiber, wherein an optical fiber and a prism are arranged on a turntable so that an incident angle of the laser beam with respect to the prism can be adjusted independently. 9. The third-order nonlinear susceptibility measuring device according to claim 8, wherein: 10. A laser beam from one laser light source is split into three, or one laser light of two laser light sources is split into two, and two of the former three beams or the latter are split. 10. The tertiary beam according to claim 8, further comprising an adjustment mechanism for rotating the prism so that the incident angle of the two split beams is symmetric with respect to a plane perpendicular to the interface between the prism and the sample. Non-linear susceptibility measurement device. 11. The method according to claim 8, wherein at least one of the three laser beams is variable in wavelength so that the wavelength characteristic of the third-order nonlinear susceptibility can be measured. Next-order nonlinear susceptibility measurement device. 12. The third-order nonlinear susceptibility measuring apparatus according to claim 8, wherein a hemispherical or semi-cylindrical prism is used. 13. The tertiary order according to claim 8, wherein a mechanism for changing the incident angle and a mechanism for measuring the intensity of reflected light are added so that the critical angle for total reflection can be measured. Non-linear susceptibility measurement device.