JP2004170095A - Waveguide structure, its manufacturing method, and surface plasmon resonance sensor and refractive index change measurement method using the waveguide structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide structure for improving the reliability in the measurement of a change in a refractive index when a measurement target has light absorption in a surface plasmon resonance sensor, to provide a method for manufacturing the waveguide structure, the surface plasmon resonance sensor, and a method for measuring the change in the refractive index. <P>SOLUTION: In the waveguide structure, a metal thin film 2 is laminated on a waveguide core layer 1, where light for measurement enters, further a dielectric film 3 that has a higher refractive index than the waveguide core on the metal thin film, and has a thickness of 1/100 to 1/10 of the light wavelength of light for measurement entering the waveguide core layer is formed. In the surface plasmon resonance sensor, a sample layer 4 is formed on the waveguide structure. In the refractive index change measurement method, the refractive index is measured by using the sensor. In the surface plasmon resonance sensor, the reliability in the measurement of the change in the refractive index when the measurement target has light absorption can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a waveguide structure and a manufacturing method thereof, and a surface plasmon resonance sensor and a refractive index change measuring method using the same.
[0002]
BACKGROUND OF THE INVENTION
The refractive index is an optical parameter that reflects a change in the characteristics of a liquid or gas. Therefore, sensors or devices that detect changes in the refractive index are used as indicators for process monitoring, are also used as detectors for chromatography and electrophoresis, and are also sensitive to ion-sensitive materials such as ionophores. Chemical sensors composed of organic film materials that cause selective adsorption or selective adsorption films based on molecular size effects using pores in the order of nanometers, and biological materials combined with enzyme reactions and antigen-antibody reactions It is also useful as a transducer for a chemical sensor.
[0003]
The present invention relates to a sensor device capable of detecting a specific target object as a chemical sensor using a refractive index measurement of a sample or a biochemical sensor. In particular, pollen, halogenated organic compounds, BTXs and nitrides, which are substances related to the air, water, and soil environment, or aldehydes, BTX, hydrocarbons, pesticides, and medical care related to the air quality of daily living space The present invention relates to a structure of a sensor used for monitoring in-hospital pathogens, antibodies, blood and urine components related to the above, and a measuring method using the sensor.
[0004]
[Prior art]
As a method for measuring the refractive index, a method using an optical prism having a shape that is smoothly polished and has a known cut-out angle has been used. These devices include a minimum declination type refractometer that determines the declination of transmitted light, an Abbe refractometer that utilizes total reflection, an immersion meter, and a Pulfrich refractometer. In addition, using an optical prism that determines the refractive index compared to a standard sample, which was developed to determine the refractive index of a substance (colloid, polymer film, etc.) whose shape is difficult to measure with the above-mentioned method. There are a reflection intensity type differential refractometer and a displacement measurement type differential refractometer using transmitted light. There is also a method of measuring the transmitted light intensity of total reflection light (JP-A-2000-146836).
[0005]
On the other hand, the surface plasmon resonance method has been used. In the surface plasmon resonance method for measuring a change in the refractive index of a dielectric material in contact with a metal surface, for example, a metal (gold, silver, etc.) thin film is formed on a light waveguide material such as glass or a polymer, and a conductive film is formed. When light is made to be totally reflected from the wave path and only the TM wave component is monitored, the light reflection intensity shows a minimum value at a certain light incident angle. Alternatively, it can be observed that the light reflection intensity shows a minimum value at a certain light wavelength, and the incident angle or wavelength of the light corresponding to the minimum value of the light reflection intensity can be observed on the metal thin film that attenuates. On the other hand, it corresponds to the refractive index of the dielectric existing on the opposite side of the waveguide material.
[0006]
Therefore, the surface plasmon resonance sensor can be configured by combining a light waveguide with a metal thin film formed thereon and an optical path to a detector that measures the total reflection condition of light and the polarization of TM waves. Therefore, there is an advantage that the configuration is relatively simple as compared with other refractometers. For example, "Planar Substrate Surface Plason Resonance Probe," Proceedings of SPIE, vol. Yee, 2 other authors, p. 178-185 (FIG. 2 on page 181).
[0007]
Further, when the surface plasmon sensor is used, a change in the refractive index of the dielectric portion opposite to the portion of the light waveguide that contacts the metal thin film can be detected. Therefore, the surface plasmon resonance sensor has the following advantages. The separation of the field of chemical or biochemical reaction from the optical system minimizes the measurement error that the chemical action directly exerts on the optical system, and therefore the change in light intensity or spectrum obtained by the detector is small. It reflects all chemical and biochemical reactions occurring outside the metal thin film. For example, it is possible to analyze an enzymatic reaction (biochemical reaction) outside a gold metal thin film ("Detectin of Electrochemical Enzymatic Reactions by Surface Plasmon Resonance Measurement Science, Vol. 73, Ryushu, Tohoku Ryushu, Tsukuba, Japan). 2 authors, pp. 1595-1598).
[0008]
Further, gold, silver, platinum, palladium, and the like can be used as the metal that can be used as the metal thin film. If the activity in physicochemical, chemical, or biochemical reactions differs depending on the type of metal, select the type of metal and design and manufacture an optimal surface plasmon resonance sensor tailored to the desired reaction. It is possible. In addition, by selecting a wavelength or a wavelength range to be used, it is possible to design and manufacture an optimum surface plasmon resonance sensor having high sensitivity according to a target reaction.
[0009]
As described above, the surface plasmon resonance sensor is a transducer that can obtain more information related to physicochemical, chemical, and biochemical reactions, and a sensor system using surface plasmon resonance is manufactured by Biocore Inc. of the United States. Has been commercialized by Japan Laser Electronics and NTT-AT in Japan.
[0010]
[Patent Document 1] JP-A-2000-146836
[Patent Document 2] Japanese Patent Application No. 2002-355353
[Patent Document 3] Japanese Patent Application No. 2002-355354
[Patent Document 4] Japanese Patent Application No. 2002-339895
[Patent Document 5] JP-A-2000-304673
[Non-Patent Document 1] "Planar Substrate Surface Plasmon Resonance Probe," Proceedings of SPIE, Vol. Yee, 2 other authors, p. 178-185 (FIG. 2 on p. 181)
[Non-Patent Document 2] "Detectin of Electrochemical Enzymatic Reactions by Surface Plasmon Resonance Measurement," Analytical Chemistry, Vol. 1595-1598
[0011]
[Problems to be solved by the invention]
However, in the case of applying a waveguide structure for a conventional surface plasmon resonance sensor, there is a problem that a substance having an absorption for a light wavelength to be used cannot accurately measure a refractive index. This is because surface plasmon resonance is sensitive to both the real and imaginary parts of the complex index of refraction.
[0012]
When a conventional waveguide structure is used to make an angle-measuring surface plasmon resonance sensor, a light wavelength that does not cause absorption of the object to be measured is selected, and a light source corresponding to the wavelength is used. The problem has been solved by redesigning the optical system including the materials of the optical prism and the polarizer according to the above, and realizing a measurement system without light absorption.
[0013]
However, since the change of the optical system involves the change of the light source and the optical material itself, it cannot be easily implemented. Furthermore, even when a substance whose extinction coefficient k is unknown is mixed as a sample, accurate measurement of the refractive index was impossible with the conventional waveguide structure.
[0014]
Therefore, in the surface plasmon resonance sensor, a device configuration for improving the accuracy of the measurement of the refractive index change when the object to be measured has light absorption is proposed.
[0015]
[Means for Solving the Problems]
In order to solve the above-described problem, the waveguide structure according to the present invention has a metal thin film laminated on a waveguide core layer on which light for measurement is incident, and further has a higher refractive index on the metal thin film than the waveguide core layer. Further, a dielectric film having a thickness of 100 to 1/10 of the light wavelength of the measuring light incident on the waveguide core layer is formed.
[0016]
Further, in the method for manufacturing a waveguide structure according to the present invention, a metal thin film is provided on a waveguide core layer on which measurement light is incident, and the light of measurement light incident on the waveguide core layer on the metal thin film is further provided. It is characterized in that a dielectric film having a thickness of 100 to 1/10 of the wavelength is formed by polymerizing an optically active organic low molecule as a starting material by a plasma process.
[0017]
Further, the surface plasmon resonance sensor according to the present invention is such that a metal thin film is laminated on a waveguide core layer on which light for measurement is incident, and further has a higher refractive index on the metal thin film than the waveguide core layer; A sample layer for providing a measurement sample on the dielectric film of the waveguide structure in which a dielectric film having a thickness of 100 to 1/10 of the light wavelength of the measurement light incident on the core layer is formed. Is formed.
[0018]
Further, the method of measuring a change in refractive index according to the present invention is characterized in that a metal thin film is laminated on a waveguide core layer into which light for measurement is incident, and further has a higher refractive index than the waveguide core layer on the metal thin film; A sample layer for providing a measurement sample on the dielectric film of the waveguide structure in which a dielectric film having a thickness of 100 to 1/10 of the light wavelength of the measurement light incident on the core layer is formed. A sample is provided on the sample layer of the surface plasmon resonance sensor on which the sample is formed, light is incident on the waveguide core layer, and the wavelength or the incident angle spectrum of the intensity transmitted through the waveguide core layer is measured to measure the sample. Is characterized by measuring the change in the refractive index.
[0019]
The sample to be measured is placed on a sample layer further outside the insulator film having a high refractive index.
[0020]
The high-refractive-index insulator film does not have a large light absorption in the light wavelength range (550 to 1000 nm) used by the surface plasmon resonance sensor, and the thickness of the film occurs on the surface of the metal thin film. The effect of surface plasmons is so thin that it reaches the sample layer. That is, the thickness of the insulator film is 1/100 to 1/10 of the wavelength of the measuring light used. This is because surface plasmon resonance cannot be generated if the above range is not satisfied. The dielectric film has an extinction coefficient k of less than 0.01. If it is 0.01 or more, the light absorption is not so small that evanescent light generated by total reflection on the metal thin film to cause the surface plasmon resonance phenomenon can reach the sample layer above the dielectric film.
[0021]
The insulator film having a high refractive index as described above can be realized, for example, as a polymer formed from an optically active organic low molecular organic solid material by a plasma process. The plasma process is useful as a method for forming an organic thin film with a controlled thickness, and since the organic thin film formed in the plasma process is a polymer having a three-dimensional network and a dense structure, it is highly sensitive to light. Has a refractive index. Further, since the constituents are mainly carbon, hydrogen, and nitrogen, light absorption is small in a light wavelength range of 550 to 1000 nm. Further, it has an insulating property, and has a characteristic of having resistance to acids and alkalis.
[0022]
[Action]
In sensing using the surface plasmon resonance phenomenon, the influence of light absorption in a layer of a sample to be measured outside the metal is large near the surface where the surface plasmon is generated, that is, from the interface between the metal thin film and the dielectric.
[0023]
For example, considering light having a wavelength of 600 nm, the influence of the k value on the intensity of reflected light is extremely large in a region of about 10 nm from the surface where the surface plasmon is generated. Conversely, if the distance from the surface plasmon generation surface is about 10 nm or more, even if the value of k is different by about 10 times, the influence on the reflected light intensity with respect to the total reflected light incident on the interface between the waveguide core layer and the metal thin film is not affected. Hardly change.
[0024]
Therefore, by forming in advance a dielectric film having a higher refractive index than the waveguide core layer on the vicinity of the metal thin film greatly affected by the value of k, the k of the sample to be measured gives the reflected light intensity. Reduce the effect. Accordingly, when the surface plasmon resonance sensor determines the change in the concentration of a product having a large k value, that is, the absorption of the measurement light, the effect of the light absorption due to the change in the concentration of the target substance is suppressed, and the change in the concentration itself is suppressed. The reflected reflected light spectrum can be obtained.
[0025]
In addition, by introducing evanescent waves with surface plasmon resonance into the high-refractive-index dielectric layer formed outside the waveguide core layer, the leakage mode loss corresponding to the refractive index of the external sample layer can be simultaneously reduced. Can be measured.
[0026]
That is, in the waveguide structure and device according to the present invention, the refractive index n of the sample material outside the high-refractive-index insulator film is determined._s, The extinction coefficient k representing the absorption of the substance_sWhen expressed as, the minimum value of the light reflection intensity detected by the surface plasmon resonance sensor is k_sCan be suppressed to a small extent.
[0027]
For example, the wavelength λ corresponding to the minimum value of the light reflection intensity_minHowever, in the conventional device, when the value of k is relatively large, such as about 0.01, even if the value of n is increased by 0.1, λ is affected by the value of k._minIndicates that the surface plasmon resonance sensor cannot determine the refractive index change corresponding to the concentration change without observing the shift to the long wavelength side. However, according to the device of the present invention, the value of k is 0.1. Even if it has an absorption of 005, λ_minIs observed to shift to the longer wavelength side, and it is possible to accurately determine the refractive index corresponding to the increase in the concentration of the product resulting from a physicochemical reaction or biochemical reaction, which is the detection purpose of the surface plasmon resonance sensor. it can.
[0028]
Even for a substance that absorbs light in the measurement region, it becomes possible to monitor a change in the refractive index using surface plasmon resonance. When the surface plasmon sensor is used, it is not necessary to select a wavelength region and redesign, so that the device application range of the surface plasmon resonance sensor is widened.
[0029]
Embodiment 1
FIGS. 1A and 1B show a surface plasmon resonance sensor according to the present invention having a waveguide structure covered with a high-refractive-index insulating film. For comparison, a configuration of a conventional surface plasmon resonance sensor is shown in FIG.
[0030]
In the waveguide structure shown in FIG. 1A according to the present invention, a refractive index N is formed on a waveguide core layer 1 made of glass or plastic having a refractive index Nw._AuIs formed with a thickness of about 30 to 50 nm, and a dielectric film 3 having a refractive index Nf (Nf> Nw) and a thickness d [nm] is formed on the gold metal thin film 2. Is formed. Further, a sample layer 4 on which a sample is placed is formed on the dielectric film 3 to form a surface plasmon resonance sensor. In a conventional surface plasmon resonance sensor, there is no dielectric film 3 and there is a sample layer 4 on which a sample is placed directly on the gold metal thin film 2.
[0031]
In the waveguide structure of FIG. 1A according to the present invention, a gold metal thin film 2 and a dielectric film 3 are directly formed on a waveguide core layer 1. On the other hand, in the surface plasmon resonance sensor of FIG. 1B, an auxiliary waveguide 5 made of the same material as the waveguide core layer 1 or a material having the same refractive index and light transmission characteristics is used. The metal thin film 2 and the dielectric film 3 are formed, and a liquid or gel-like matching oil layer 6 for establishing an optical coupling is sandwiched between the waveguide core layer 1 and the auxiliary waveguide 5.
[0032]
Regarding the method of introducing the incident light 7 into the waveguide core layer 1 of the light, the light is incident through a spherical type whose surface is optically polished or a prism cut at an appropriate angle, or the angle is adjusted by a lens and the light is collected. It is conceivable that the incident light directly enters the waveguide core layer 1 or that the light enters the waveguide core layer 1 using an optical fiber connection technique.
[0033]
The outgoing light 8 can be led to the detector by spatial propagation or propagation by an optical fiber. A polarizer 9 for selectively transmitting the TM wave is provided between the emitted light 8 and the detector, thereby forming a device for a surface plasmon resonance sensor.
[0034]
The incident light 7 of wavelength λ is incident angle θ₀At 10, the interface between the waveguide core layer 1 and the gold metal thin film 2 is subjected to the following total reflection condition “θ₀> Sin^-1(N_Au/ Nw), where N_AuIs made to satisfy the “refractive index of gold”. The surface plasmon propagates along the interface between the gold metal thin film 2 and the dielectric film 3 thereabove according to the traveling direction of the incident light.
[0035]
The sample layer 4 on the dielectric film 3 has a refractive index n_sExtinction coefficient k_sIn this case, the emitted light 8 is measured by a detector, and the minimum value of the light reflection intensity is determined by the incident angle θ.₀Alternatively, the refractive index N of the sample layer 4 is obtained by sweeping the incident light wavelength λ._sΛ corresponding to the minimum value of the light reflection intensity_minOr θ_minCan be requested.
[0036]
The effect of the present invention is shown by a calculation simulation based on the Fresnel reflectance formula. The value used here was 1.54 as the value of Nw, the thickness of the insulating film having a high refractive index was the same as that of the gold metal thin film, and d was 25 nm. N of the sample_sIs 1.34 and 1.35, k representing light absorption_sIs changed to 0.001 or 0.005, and the calculation is performed assuming FIG. 8 which is a conventional surface plasmon resonance sensor, as shown in FIG._minIs N_sIs k at 1.34_sIs 0.008, then n_sIs 1.35 and k_sIs longer than when the wavelength is 0.0005. On the other hand, in the calculation on the assumption of FIGS. 1A and 1B according to the present invention, as shown in FIG._sIs 1.35 and k_sIs 0.0005, λ_minIs n_sIs k at 1.34_sIs longer than when 0.008 is used. Therefore, k representing light absorption_sIn the surface plasmon resonance sensor according to the present invention, even when the value of_sCan be accurately determined.
[0037]
Embodiment 2
As an experiment corresponding to the above case, a case is shown in which methylene blue of a dye is used as a substance having light absorption, and aqueous solutions of methylene blue having different concentrations are measured with a surface plasmon resonance sensor according to the present invention and a conventional surface plasmon resonance sensor. First, the features of the high refractive index insulator film used in the present invention will be described. The waveguide structure was manufactured by the method described in Japanese Patent Application Nos. 2002-355353, 2002-355354, and 2002-339895.
[0038]
As the insulator film having a high refractive index, a thin film (produced based on JP-A-2000-304673) using an amino acid as an organic solid material as a raw material by a sputtering method was used. As shown in FIG. 3, in a wide light region from 300 nm to 1000 nm, it has a refractive index of 1.65 or more, and further, in a range from 500 nm to 1000 nm, the refractive index changes from 1.65 to 1.7. This film does not have anomalous dispersion of the refractive index that changes smoothly. Further, as shown in FIG. 4, the value of k is 0.04 at 500 nm, but has a feature that it becomes smaller in a wavelength range from 1000 nm to 1000 nm.
[0039]
As described above, the organic insulator film made of an amino acid as an organic solid material by sputtering is an insulating material having no high absorption in the visible region and having a high refractive index of about 1.65. On the other hand, it is known that gas molecules can be absorbed and desorbed in response to changes in the concentration of volatile molecules in the atmosphere outside the sputtered organic insulator film formed from amino acids. As shown in FIG. 5, using an angle detection type surface plasmon resonance sensor and using incident light of 870 nm, sputter organic insulation using amino acids formed on a gold metal thin film on a slide glass (BK7) as a raw material. When the body film is exposed to a 1 ppm carboxyl gas atmosphere and when exposed to 0 ppm (air), the incident angle θ corresponding to the refractive index_minCan be observed by repeating the increase or decrease of 0.001 deg. Further, a sputtered organic insulator film made of amino acids is an organic insulator film having chemical stability that does not dissolve in an organic solvent represented by water, alcohol, and hexane. It can be expected that a film interface can be formed.
[0040]
By this sputtering method, an organic insulator film using an amino acid as an organic solid material as a raw material was formed on the polymer waveguide core layer 1 on which a gold metal thin film was formed.
[0041]
A xenon lamp capable of emitting visible light having a wavelength of 300 to 1000 nm is used as a light source. A polarizer 10 for TM wave was installed on the end face of the device where the emitted light 8 emerged, and guided to a CCD camera (wavelength resolution: 1 nm) as a detector by spatial propagation.
[0042]
About the methylene blue aqueous solution, the concentration is about 0.1 to 0.02 molL.^-1FIG. 6 (a) shows the result of measurement by dropping the sample prepared in step 1 onto a conventional device, and FIG. 6 (a) shows the result of measurement by dropping the sample on an organic insulator film using amino acid as an organic solid material by sputtering. FIG. 6 (b). The sample concentration was 18 μmolL for sample I.^-1, Sample II is 92 μmolL^-1, Sample III is 1 mmolL^-1It is. Methylene blue is a dye that has light absorption from around 600 nm.
[0043]
In FIG. 6A, which is the result of using the conventional device, when the sample I having a low concentration and the sample III having a high concentration are measured, the reflectance spectrum is shifted in the vertical axis direction. No axial shift is observed. That is, λ_minIs almost constant. This is considered because the reflected light intensity fluctuates due to the influence of light absorption in the sample layer.
[0044]
On the other hand, when the surface plasmon resonance sensor is used, as shown in FIG. 6B, the dip position changes to the longer wavelength side without a large change in the shape of the reflectance spectrum. Δλ_minWas positive 12 nm. The dip depth of the reflectance spectrum is clearly deeper than the result of FIG. 6A using the conventional surface plasmon resonance sensor._minIs important in that the accuracy of the fitting for obtaining the value of is increased.
[0045]
Further, when the surface plasmon resonance sensor according to the present invention is used, the dip in the reflectance spectrum is deepened, which is also consistent with the simulation result in FIG. Also, λ_min2 appear at around 600 nm, which is on the longer wavelength side as compared with around 550 nm in FIG. 6A using the conventional surface plasmon resonance sensor, which is a result consistent with the simulation result of FIG. is there.
[0046]
As shown in the graph of FIG. 7, a linear relationship appears in the value of the wavelength corresponding to the minimum value of the reflectance with respect to the logarithm of the methylene blue aqueous solution concentration. That is, it is shown that a change in the refractive index of methylene blue having light absorption can be determined by a surface plasmon resonance sensor device for a methylene blue solution having light absorption. From the calibration curve obtained from this graph, using a detector with a wavelength resolution of 1 nm, about 0.18 molL^-1It can be seen that the change in the concentration of the methylene blue aqueous solution of / m can be detected as a change using the refractive index as a parameter.
[0047]
FIG. 8 shows a reflected light spectrum obtained by the surface plasmon resonance sensor according to the present invention when the concentration of the aqueous solution of sodium perchlorate having no absorption in the measurement wavelength range is changed. Thus, 0.5 molL^-1/ Nm and 3.5 molL^-1/ Nm aqueous solution of sodium perchlorate at 591.9 nm and 616.8 nm, respectively._minIs observed. Therefore, a refractive index measurement based on surface plasmon resonance is performed on a substance having no absorption.
[0048]
【The invention's effect】
According to the present invention as described above,
(1) In a surface plasmon resonance sensor, even when a sample is used, which absorbs the measurement light to be used, the entire light reflectance spectrum expressing the surface plasmon resonance does not significantly shift, and Λ corresponding to refractive index change_minOr θ_minIs obtained.
[0049]
(2) Further, due to a plasma process using an amino acid which is an organic solid material as a starting material, an organic insulator having no high light absorption between 550 nm and 1000 nm and having a high refractive index of about 1.65 to 1.7. The film can be formed.
[0050]
(3) A sensor device that can accurately detect a change in refractive index by a surface plasmon resonance method for a sample that absorbs measurement light is a high-refractive-index organic insulating material manufactured by a plasma process from an amino acid that is an organic solid material This can be realized by forming the body film on a metal thin film formed on the waveguide core layer. As a result, even for an aqueous solution having absorption in the measurement light, the λ_minAnd the logarithm of the concentration can be linearly determined.
[0051]
As described above, the fact that the dip of the reflection spectrum is obtained as a deep dip that is sharp and has a small half-value width increases the accuracy of calculation for determining the minimum value of the reflectance, and therefore, the surface plasmon resonance sensor This makes it possible to obtain high sensitivity. In addition, compared to conventional products, the wavelength-dependent reflectance spectrum is obtained as a dip in a narrower wavelength range, which is advantageous in that it is easy to increase the resolution in an optical system tailored to a specific target substance, or There is an advantage that a cheaper optical system can be designed.
[0052]
As described above, an ion-sensitive material such as an ionophore, an organic film material that causes selective adsorption, or a molecule using a nanometer-order hole is formed on the device configuration of the surface plasmon resonance sensor according to the present invention. High-sensitivity detection of changes in the refractive index caused by low-molecular-weight substances, which occur in the sample layer such as the selective adsorption film due to the size effect, enables high-sensitivity detection that was not possible with conventional surface plasmon resonance sensor devices. , An enzyme sensor, an antigen-antibody reaction sensor, a gas sensor, and the like can be realized based on surface plasmon resonance.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a surface plasmon resonance sensor having a high refractive index insulator film based on the Kretschmann type according to the present invention.
FIG. 2 (a) is a surface plasmon resonance sensor of the present invention (with a high refractive index dielectric film), and FIG. 2 (b) is a refractive index n by a conventional surface plasmon resonance sensor (without a high refractive index dielectric film). The figure which shows the simulation result of the reflectance with respect to the sample which has extinction coefficient k.
FIG. 3 is a diagram showing data on the relationship between the wavelength and the refractive index of a dielectric film of an organic insulator film formed by a plasma process using an amino acid as a solid material by spectroscopic ellipsometry.
FIG. 4 is a diagram showing data on the relationship between the wavelength and the extinction rate of a dielectric film of an organic insulator film formed by a plasma process using an amino acid as a solid material by spectroscopic ellipsometry.
FIG. 5 shows 1 ppm of carboxy gas and 0 ppm of a dielectric film of a sputtered organic insulator film formed from an amino acid as a raw material formed on a gold metal thin film on a slide glass (BK7) using incident light of 870 nm. Θ when exposed to (air)_minFIG.
FIG. 6 (a) Measurement of an aqueous methylene blue sample using a surface plasmon resonance sensor of the present invention (with a high refractive index dielectric film) and (b) a conventional surface plasmon resonance sensor (without a high refractive index dielectric film) The figure which shows a result.
FIG. 7 is a diagram showing a calibration curve for measuring a methylene blue aqueous solution using a surface plasmon resonance sensor (with a dielectric film having a high refractive index) of the present invention.
FIG. 8 is a view showing a reflectance spectrum of an aqueous solution of sodium perchlorate measured by a surface plasmon resonance sensor (with a dielectric film having a high refractive index) of the present invention.
FIG. 9 is a configuration diagram of a conventional surface plasmon resonance sensor.
[Explanation of symbols]
1 Waveguide core layer
2 Metal thin film
3 Dielectric film
4 Sample layer
5 Auxiliary waveguide
6 Layer of matching oil
7 Incident light
8 Outgoing light
9 Polarizer that selectively transmits TM waves
10 Incident angle θ₀

Claims (14)

A metal thin film is laminated on the waveguide core layer on which the light for measurement is incident, and further has a higher refractive index than the waveguide core layer on the metal thin film, and the light for measurement incident on the waveguide core layer. A waveguide structure, wherein a dielectric film having a thickness of 100 to 1/10 of the light wavelength is formed. 2. The waveguide structure according to claim 1, wherein the dielectric film has a light extinction coefficient smaller than 0.01. 3. The waveguide structure according to claim 1, wherein said dielectric film has an insulating property. The waveguide structure according to claim 3, wherein the dielectric film is a polymer formed by a plasma process using an optically active low molecular organic compound as a starting material. The waveguide structure according to claim 4, wherein the starting material is an amino acid. A metal thin film is provided on a waveguide core layer on which measurement light is incident, and a thickness of 100 to 1/10 of the light wavelength of the measurement light incident on the waveguide core layer on the metal thin film. A method for manufacturing a waveguide structure, comprising forming a dielectric film. 7. The method according to claim 6, wherein the dielectric film is formed by polymerizing an optically active organic low molecule as a starting material by a plasma process. The method according to claim 7, wherein the starting material is an amino acid. A metal thin film is laminated on a waveguide core layer on which measurement light is incident, and further has a higher refractive index than the waveguide core layer on the metal thin film, and light of measurement light incident on the waveguide core layer. Surface plasmon resonance characterized in that a sample layer for providing a sample for measurement is formed on the dielectric film of the waveguide structure in which a dielectric film having a thickness of 100 to 1/10 of the wavelength is formed. Sensors. The surface plasmon resonance sensor according to claim 9, wherein the sample layer and the metal thin film are insulated. The surface plasmon resonance sensor according to claim 10, wherein the dielectric film has an insulating property. The surface plasmon resonance sensor according to claim 11, wherein the dielectric film is a polymer formed by a plasma process using an optically active organic low molecule as a starting material. The surface plasmon resonance sensor according to claim 12, wherein the starting material is an amino acid. A metal thin film is laminated on a waveguide core layer on which measurement light is incident, and further has a higher refractive index than the waveguide core layer on the metal thin film, and light of measurement light incident on the waveguide core layer. The sample layer of the surface plasmon resonance sensor in which a sample layer for providing a sample for measurement is formed on the dielectric film having a waveguide structure in which a dielectric film having a thickness of 100 to 1/10 of the wavelength is formed. A sample is provided, light is incident on the waveguide core layer, and a change in the refractive index of the sample is measured by measuring a wavelength or an incident angle spectrum of an intensity transmitted through the waveguide core layer. Refractive index change measurement method.

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