Spectrum sensor based on ultra-narrow band surface outer surface lattice resonance mode and application thereof

Abstract

The invention discloses a spectrum sensor based on an ultra-narrow band surface outer surface lattice resonance mode and application thereof.The spectrum sensor comprises a substrate, a dielectric grating located on the upper surface of the substrate and a V-shaped metal nanometer antenna array covering the upper surface of the dielectric grating, the top end of the dielectric grating is triangular, and the top end of the dielectric grating is triangular. A metal nano antenna in the V-shaped metal nano antenna array is of an asymmetric V-shaped structure with two arms different in length, coherent coupling between out-of-plane dipoles in the V-shaped metal nano antenna array finally forms an out-of-plane SLR mode, and the spectrum sensor based on the ultra-narrow-band out-of-plane SLR mode is high in quality factor and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano optical sensors, and in particular to a spectrum sensor based on an ultra-narrow-band out-of-plane surface lattice resonance mode and applications thereof. Background Art

[0002] Spectral sensing is a technology that detects the properties and states of materials by measuring and analyzing the interaction between light and matter. This technology is widely used in various fields, including environmental monitoring, food safety, and pharmaceutical research and development, providing important support for scientific research and industrial production. Under normal circumstances, the interaction between light and matter is very weak. Therefore, it is difficult to meet the needs of application and commercialization by directly using this technology to detect the properties of materials. How to effectively enhance the interaction between light and matter is a key factor in improving the performance of this technology. Plasmons, including localized surface plasmon resonance (LSPR) and propagating surface plasmon polariton (SPP), have subwavelength electric field localization and extremely strong electromagnetic field enhancement capabilities, which can greatly enhance the interaction between light and matter. At the same time, LSPR and SPP also have high response sensitivity to changes in the refractive index of the local environment. These characteristics have promoted the development and application of spectral sensors based on LSPR and SPP. In 1990, Pharmacia Biosensor AB (now Cytiva) developed the first commercial SPP sensor. Currently, the upper limit of the figure of merit (FOM) of commercial SPP sensors in the visible light band is 108 (the resonance bandwidth of SPP is generally 7-10nm). The sensor quality factor is defined as FOM = S / Δλ, where S = Δλ s / Δn represents the response sensitivity of the sensor, Δλ is the half-height full width of the SPP resonance mode, Δλ s is the spectral shift of the resonance mode with the change of refractive index Δn.

[0003] In recent years, people have found that the nanoarray structure can also support another narrower resonance mode, which is generated by the LSPR coherent coupling of the unit cell and is named the surface lattice resonance mode (SLR). When the LSPR resonance wavelength of the unit cell matches the period of the array structure, the resonance linewidth of the SLR can reach 0.9nm in the visible light band. Obviously, this can further improve the performance of spectral sensors. However, the surface lattice modes supported by the above structures, including other high-performance in-plane or out-of-plane surface lattice modes proposed by previous researchers, need to work in an environment with a uniform refractive index distribution or a specific asymmetric refractive index distribution (that is, the upper cover of the structure has the same refractive index as the lower substrate of the supporting structure or both have a specific refractive index distribution). Slight changes in the environmental refractive index distribution will greatly affect the resonance linewidth of the SLR, which greatly limits the application of this mode in high-performance sensing. Summary of the invention

[0004] The purpose of the present invention is to provide a spectrum sensor based on ultra-narrowband out-of-plane surface lattice resonance mode to solve the problem of poor performance of SPP spectrum sensors in the prior art. The resonance bandwidth of the spectrum sensor is not only independent of the distribution of the refractive index of the external environment, but also breaks the limitation that the out-of-plane SLR mode can only be excited by oblique incident light.

[0005] Another object of the present invention is to provide a method for preparing the spectral sensor based on the ultra-narrow-band out-of-plane surface lattice resonance mode.

[0006] Another object of the present invention is to provide an application of the spectral sensor based on the ultra-narrow-band out-of-plane surface lattice resonance mode in environmental refractive index detection and biological sample detection.

[0007] The technical solution adopted to achieve the purpose of the present invention is:

[0008] A spectral sensor based on an ultra-narrowband out-of-plane surface lattice resonance mode comprises a substrate, a dielectric grating located on the upper surface of the substrate, and a V-shaped metal nanoantenna array covering the upper surface of the dielectric grating. The metal nanoantennas in the V-shaped metal nanoantenna array are asymmetric V-shaped structures with two arms of different lengths.

[0009] The dielectric grating is located between the substrate and the V-shaped metal nano-antenna array and is used to make a template for the V-shaped metal nano-antenna array. The structural parameters of the dielectric grating are optimized and determined by performing parameter scanning according to the working principle and working wavelength of the spectral sensor.

[0010] The V-shaped metal nanoantenna array uses the dielectric grating as a template and is deposited on the surface of the dielectric grating at a certain tilt angle using vacuum thermal evaporation technology. The tilt angle is selected and adjusted according to the modulation depth and period of the dielectric grating.

[0011] Under the action of incident light waves, the V-shaped metal nanoantenna forms an out-of-plane dipole resonance due to the coupling between the symmetric and asymmetric plasmon modes supported by the structure; the coherent coupling between the out-of-plane dipoles in the V-shaped metal nanoantenna array eventually forms an out-of-plane SLR mode.

[0012] In the above technical solution, the material of the substrate is silicon dioxide.

[0013] In the above technical solution, the material of the dielectric grating is 3170 photoresist (PR); it is prepared by interference lithography; the cross-section of the dielectric grating is a triangle or a triangle with rounded corners at the top, the period Λ of the dielectric grating is 450-600nm, preferably, Λ≈500nm, and other structural parameters, such as the modulation depth h and the angle α at the top of the dielectric grating, are optimized and determined by parameter scanning through FDTD Solution software based on the working principle and working wavelength of the spectral sensor. Preferably, the modulation depth h of the dielectric grating is 270nm, and the angle α at the top of the dielectric grating is 65°.

[0014] In the above technical solution, the material of the V-shaped metal nano-antenna array is a metal material with low absorption, such as silver, aluminum, sodium or platinum; the thickness d of the V-shaped metal nano-antenna is 50-100nm, preferably, d≈90nm, and other structural parameters, such as the height H of the nano-antenna, the asymmetric factor β (β is defined as the difference h between the two arms of the V-shaped antenna along the light transmission direction 1 The ratio of the height H of the nanoantenna is determined by optimizing the parameters by scanning the FDTD Solution software. Preferably, the height H is 360 and the asymmetric factor β is 0.3.

[0015] Another aspect of the present invention also includes a method for preparing the spectral sensor, comprising the following steps: preparing the dielectric grating on the upper surface of the substrate by interference lithography, and then evaporating the same thickness of silver on both sides of the dielectric grating at a predetermined inclination angle by vacuum thermal evaporation to form a V-shaped metal nanoantenna.

[0016] Another aspect of the present invention also includes a detection system based on the spectral sensor, wherein the spectral sensor is encapsulated in a transparent medium cavity, the transparent medium cavity is fixed on a rotating platform rotating around the z-axis, and the transparent medium cavity is connected to a medium outlet and a medium inlet. The incident light source irradiates the spectral sensor in the transparent medium cavity after passing through a semi-transparent and semi-reflective mirror. After exciting the spectral sensor, the light wave carrying the resonance signal is reflected by the semi-transparent and semi-reflective mirror, and then transmitted to the spectrometer through the optical fiber.

[0017] Another aspect of the present invention also includes the application of the spectral sensor or detection system in medium refractive index detection.

[0018] Another aspect of the present invention also includes the use of the spectral sensor or detection system in the detection of the concentration of an object to be detected in a medium.

[0019] In the above technical solution, the medium is gas or liquid.

[0020] In the above technical solution, the method for detecting the refractive index or concentration of a medium using the detection system comprises the following steps:

[0021] Step 1: Fix the angle of the rotating platform, turn on the incident light source, and the spectrometer detects the reflection valley of the spectral sensor based on the SLR mode and records the central resonance wavelength λ of the reflection valley. 1 Preferably, the incident angle θ of the incident light source is 0° to 30°;

[0022] Step 2: Take standard samples of different concentrations or different refractive indices and fill them into the transparent medium cavity in turn. The spectrometer detects the reflection valley of the spectrum sensor based on the SLR mode in turn and records the central resonance wavelength λ of the reflection valley. 2 , calculate the overall offset of the reflection valley Δλ=λ 2 -λ 1 , establish a standard curve of concentration-Δλ or refractive index-Δλ;

[0023] Step 3: Fill the sample to be tested into the transparent medium cavity, and the spectrometer detects the reflection valley of the spectrum sensor and records the central resonance wavelength λ of the reflection valley. ′ , calculate the overall offset Δλ of the reflection valley ′ =λ ′ -λ 1 , Δλ ′ Substitute the standard curve to solve the concentration or refractive index of the sample to be tested.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The spectral sensor based on the ultra-narrowband out-of-plane SLR mode provided by the present invention not only has a very high quality factor (170), but also has no requirements for the distribution of the refractive index of the environment in which the device is located. Therefore, it is suitable for various types of sensing detection (refractive index and biological / chemical sensing, etc.) and has a wider application prospect.

[0026] 2. The ultra-narrowband out-of-plane SLR mode spectral sensor provided by the present invention breaks the limitation that the out-of-plane SLR mode spectral sensor can only work under oblique incident light (generally the angle of incident light θ>>10°).

[0027] 3. The ultra-narrow-band out-of-plane SLR mode spectral sensor provided by the present invention has a simple structure, is easy to process, and has low cost. It can be prepared over a large area, laying an application foundation for realizing mass production of SLR mode spectral sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure shows the structure schematic diagram of the spectrum sensor based on the ultra-narrow-band out-of-plane SLR mode;

[0029] In the figure, 1-substrate, 2-dielectric grating, 3-V-shaped metal nanoantenna array, 3-1-first arm, 3-2-second arm;

[0030] Figure 2 The figure shows the working principle of the ultra-narrow-band out-of-plane SLR mode spectral sensor;

[0031] Figure 3 (a) and (b) show the reflection spectrum response results of the sensor when the angle between the propagation direction of the incident light and the normal direction of the structure is 0 degree and 20 degree, and the upper cover of the structure is air; (c) is the numerical simulation of the electric field distribution of the above sensor at the SLR resonance wavelength under the action of normal incident light;

[0032] Figure 4 Shown is a schematic diagram of a detection system based on a spectral sensor;

[0033] A-spectral sensor, 4-transparent medium cavity, 4-1-medium inlet, 4-2-medium outlet, 5-incident light source, 6-semi-transparent and semi-reflective mirror, 7-optical fiber;

[0034] Figure 5 The following are the sensing test results of the ultra-narrowband out-of-plane SLR mode spectral sensor under different incident light angles. (a)-(c): Sensing test results of the above sensor for glucose solutions with different concentrations when the incident light angles are 0°, 12° and 16° respectively;

[0035] Figure 6Shown is a summary of the test results based on the ultra-narrowband out-of-plane SLR mode spectral sensor;

[0036] Figure 7 (a) and (b) show the test of low concentration urea based on the ultra-narrow band out-of-plane SLR mode spectral sensor and the standard deviation distribution of multiple repeated results. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] Example 1

[0039] A spectral sensor based on ultra-narrowband out-of-plane surface lattice resonance modes, such as Figure 1 As shown, it includes a substrate 1, a dielectric grating 2 and a V-shaped metal nanoantenna array 3;

[0040] The substrate 1 is silicon dioxide (SiO 2 ) material, the refractive index of silicon dioxide in the optical band is about 1.46.

[0041] The dielectric grating 2 is located between the substrate 1 and the metal nano-antenna array 3, and is mainly used as a template for preparing the metal nano-antenna array 3. The material selected for the dielectric grating 2 is 3170 photoresist (PR). The dielectric grating 2 is prepared by interference lithography. The dielectric grating 2 is guided by the formation mechanism of the out-of-plane surface lattice resonance, and the structural parameters of the dielectric grating 2 are optimized and determined by parameter scanning through the FDTDSolution software. In this embodiment, the working band of the ultra-narrow band out-of-plane surface lattice resonance mode spectrum sensor is 450-800nm. The structural parameters of the dielectric grating are optimized and determined according to this working wavelength: grating period Λ=500nm, modulation depth h≈270nm, and the angle α of the triangle determined by the top of the dielectric grating 2 is 65°.

[0042] The material used for the V-shaped metal nanoantenna array 3 is silver (Ag). The dielectric grating 2 is used as a template, and a certain thickness of silver is evaporated to both sides of the dielectric grating 2 at a specific tilt angle by using vacuum shadow evaporation technology to form a V-shaped metal nanoantenna. The tilt angle of evaporation is appropriately adjusted according to the modulation depth of the dielectric grating 2 and the overall duty cycle of the dielectric grating 2. The V-shaped metal nanoantenna is an asymmetric V-shaped structure, and the lengths of the first arm 3-1 and the second arm 3-2 are different. The thickness of the V-shaped metal nanoantenna array 3 is d≈90nm, the total height of the V-shaped metal nanoantenna array 3 is H=360nm, and the asymmetry factor β=0.3.

[0043] Example 2

[0044] This embodiment is based on the ultra-narrow-band out-of-plane SLR mode spectral sensor described in Embodiment 1, and introduces its working principle.

[0045] The working principle of the spectral sensor based on the ultra-narrowband out-of-plane surface lattice resonance mode is as follows: Figure 2 As shown: the symmetrical V-shaped metal nanoantenna can support asymmetric (E a ) and symmetry (E s ) LSPR mode. The excitation of these two modes requires the polarization direction of the incident light to be along the x-axis (i.e., TM polarization) and the z-axis, respectively, see Figure 2 (a) and Figure 2 As shown in (b). The illustrations in the two figures show the far-field radiation characteristics of the two modes. It can be seen that the two modes are respectively manifested as sub-radiative resonance in the plane (due to the high-order resonance of the V-shaped antenna) and dark resonance out of the plane. For sub-radiative or dark resonators with extremely weak radiation capabilities, the surface lattice mode formed by the coherent coupling between the resonator arrays usually requires oblique incident light to excite (θ>>10°), which poses certain challenges to the existing microscopic spectroscopy test system.

[0046] When the symmetry of the V-shaped antenna plane is broken, due to the asymmetric polarization of the structural charge, the E of the structure can be simultaneously excited by the normally incident TM polarized light. a and E s The coherent coupling between the two modes can realize an out-of-plane dipole resonance along the short arm direction of the V-shaped antenna. Figure 2 The illustration in (c) shows the far-field radiation characteristics of the hybrid out-of-plane dipole resonance. Since the dipole resonance mode has an in-plane radiation component, it can be directly excited by normal incident light. In addition, the brightness of the mode, or the quality factor Q of the mode (Q = λ / Δλ, where λ and Δλ represent the central resonance wavelength and the half-height full width of the resonance mode, respectively) can be modulated by adjusting the angle α between the two arms of the V-shaped antenna and the asymmetry factor β of the structure.

[0047] Finally, based on the coherent coupling between the above-mentioned hybrid out-of-plane dipole arrays, or ultimately equivalent to the interaction between the V-shaped antenna and the surface diffraction mode, an out-of-plane surface lattice resonance is achieved, which can be directly excited by normal incident light and whose Q value can be tuned.

[0048] Figure 3 (a)-(b) show the reflectance spectra of the ultra-narrowband out-of-plane SLR mode sensor described in Example 1. It can be seen that the out-of-plane SLR mode has an extremely narrow linewidth, and its half-maximum full width is 3.8nm and 3nm at θ=0° and 20°, respectively, which is very suitable for high-performance sensing applications. Figure 3(c) shows the electric field distribution of the SLR at the resonance wavelength of the sensor described in Example 1 when θ=0°. The electric field distribution fully verifies that the device is realized by out-of-plane dipole coherent coupling.

[0049] Example 3

[0050] This embodiment is based on the application of Embodiment 1 in detecting the refractive index of the environmental medium.

[0051] This embodiment applies the spectral sensor of embodiment 1 to the detection system mentioned in the Chinese patent publication number CN116773493A “A dual-function hybrid plasmon sensor and its application”, specifically:

[0052] like Figure 4 As shown, a detection system based on ultra-narrow band surface lattice resonance sensing includes the spectral sensor A described in Example 1, and the spectral sensor A is fixed in a transparent medium cavity 4. The liquid (gas) to be tested is pumped into the transparent medium cavity 4 from the medium inlet 4-1, and the liquid (gas) fills the entire transparent medium cavity 4 and then flows out from the medium outlet 4-2, forming a stable circulation system with the liquid (gas) to be tested in the outside world. The transparent medium cavity 4 is fixed on a rotating platform that can rotate around the z-axis, and adjusting the angle of the rotating platform can be equivalent to changing the angle of the incident light relative to the structural normal.

[0053] A broadband plane wave is used as the incident light source 5 to illuminate the spectral sensor A, and the incident light source 5 is TM polarized. The broadband incident light wave passes through the semi-transparent and semi-reflective mirror 6 and then illuminates the surface of the spectral sensor A, and excites the SLR mode in the spectral sensor A. Subsequently, the light wave carrying the resonance signal is reflected by the semi-transparent and semi-reflective mirror 6, and then transmitted to the spectrometer through the optical fiber 7, and the slight change of the refractive index or concentration of the ambient medium (liquid or gas) is detected by monitoring the spectral shift of the resonance mode in the spectrometer.

[0054] When the incident light wave irradiates the ultra-narrow-band surface lattice resonance sensing detection system, a signal such as Figure 3 The extremely narrow reflection valley shown in . When the refractive index of the liquid or gas filled in the transparent medium cavity changes, the wavelength of the reflection valley will shift by a certain amount. Since the surface lattice mode is generated by the coupling of the localized surface plasmon of the nanoantenna and the optical surface diffraction mode, the movement of the central resonance wavelength with the refractive index of the external environment can be approximately expressed by the following formula:

[0055] Δλ s = ΛΔn

[0056] Where Δλ srepresents the spectral shift of the surface lattice mode when the ambient refractive index changes by Δn, and Λ represents the period of the V-shaped metal nanoantenna array. It can be seen that when the period of the nanoantenna array remains unchanged, the shift of the sensor's resonant wavelength is linearly related to the change in the ambient refractive index. In other words, the response sensitivity of the sensor is only related to the period of the antenna array, that is, s = Δλ s / Δn=Λ=500nm / RIU. Therefore, the change in the ambient refractive index can be inferred by detecting the shift in the resonance wavelength.

[0057] In this embodiment, we tested glucose solutions of different concentrations. The greater the concentration of the glucose solution, the greater the corresponding refractive index. Using the sensor described in Example 1, we tested its sensing response signals to glucose aqueous solutions with mass ratios of 1%, 3%, 5% and 10%. The results are as follows: Figure 5 shown. Figure 5 (a)-(c) show the sensor test results when the incident light angles are 0°, 12° and 16° respectively. The black dotted line in the figure indicates the central resonance wavelength of the SLR mode in pure water solution (i.e. 0% glucose solution) and 10% glucose solution. It can be seen from the sensor test results that under the action of incident light at different angles, the central resonance wavelength of the SLR has a significant red shift with the increase of the concentration of the glucose solution. Figure 5 Summary Figure 4 From the sensor test results shown, it can be seen that the response sensitivity of the sensor is basically the same under the action of incident light at different angles. Figure 6 The green box in the figure shows the refractive index of glucose solutions of different concentrations tested by Abbe refractometer. Based on this, it can be calculated that the detection sensitivity of the sensor is 512nm / RIU, 495nm / RIU and 509nm / RIU at three incident angles. This is basically consistent with the sensitivity of the sensor calculated theoretically. The calculated highest quality factor (FOM) of the sensor can reach 170, which is much higher than the quality factor of commercial surface plasmon-based sensors.

[0058] Example 4

[0059] Urea solutions of different concentrations were introduced into the sensor detection system described in Example 3 to test the detection limit of the sensor detection system for substance concentration. In the experiment, we configured urea with molar concentrations of 2, 4, 6, 20, 40 and 60 μmol / ml respectively, and tested the response characteristics of the sensor shown in Example 1 to different concentrations of urea. The results are shown in Figure 2. Figure 7As shown in (a). It can be seen that when the medium environment of the sensor changes from pure water environment to urea solution of different concentrations, the central resonance wavelength of the SLR mode has a certain red shift; when the concentration of urea is very low, the red shift of the spectrum is relatively small. In order to verify the reliability of the above sensing experiment when testing low-concentration substances, after testing a group of 2-60μmol / ml samples and repeatedly rinsing the sensor, we repeated the test 10 times. Figure 7 (b) shows the standard deviation distribution of the results of repeated detection. It can be seen that when detecting a urea solution with a concentration of 2μmol / ml, the standard deviation of the multiple measurements is greater than the spectral shift corresponding to the concentration change in the SLR mode, which means that the sensor system cannot accurately distinguish a 2μmol / ml urea solution. When the concentration of the urea solution increases to 6μmol / ml, the standard deviation of the multiple tests is less than the spectral shift corresponding to the SLR mode, and the average spectral shift is consistent with the overall response sensitivity of the sensor, which means that the sensor has a relatively stable and reliable response to urea solutions of this concentration. Therefore, we can conclude that the detection limit of the system for urea solutions is approximately 6μmol / ml.

[0060] Example 5

[0061] Through the performance verification of Example 3 and Example 4, it can be known that the ultra-narrow-band surface lattice resonance sensing detection system can be well applied to the medium refractive index or medium concentration. The specific detection method includes the following steps:

[0062] Step 1, fix the angle of the rotating platform, turn on the incident light source 5, and the spectrometer detects the reflection valley of the spectrum sensor A based on the SLR mode, and records the central resonance wavelength λ of the reflection valley 1 Preferably, the incident angle θ of the incident light source 5 is 0° to 30°;

[0063] Step 2: Standard samples of different concentrations or different refractive indices are sequentially filled into the transparent medium cavity 4, and the spectrometer sequentially detects the reflection valley of the spectrum sensor A based on the SLR mode, and records the central resonance wavelength λ of the reflection valley. 2 , calculate the overall offset of the reflection valley Δλ=λ 2 -λ 1 , establish a standard curve of concentration-Δλ or refractive index-Δλ;

[0064] Step 3: Fill the sample to be tested into the transparent medium cavity 4, and the spectrometer detects the reflection valley of the spectrum sensor A and records the central resonance wavelength λ of the reflection valley. ′ , calculate the overall offset Δλ of the reflection valley ′ =λ ′ -λ 1 , Δλ′ Substitute the standard curve to solve the concentration or refractive index of the sample to be tested.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A spectral sensor based on ultra-narrowband out-of-plane surface lattice resonance mode, characterized in that: The invention comprises a substrate, a dielectric grating located on the upper surface of the substrate, and a V-shaped metal nanoantenna array covering the upper surface of the dielectric grating. The metal nanoantennas in the V-shaped metal nanoantenna array are asymmetric V-shaped structures with two arms of different lengths. The coherent coupling between the out-of-plane dipoles in the V-shaped metal nanoantenna array eventually forms an out-of-plane SLR mode.

2. The spectral sensor based on ultra-narrowband out-of-plane surface lattice resonance mode according to claim 1, characterized in that: The material of the substrate is silicon dioxide.

3. The spectral sensor based on ultra-narrowband out-of-plane surface lattice resonance mode according to claim 1, characterized in that: The material of the dielectric grating is PR, the cross-section of the dielectric grating is a triangle or a triangle with rounded top, the period Λ of the dielectric grating is 450-600nm, the modulation depth h of the dielectric grating is 200-350nm, and the angle α of the top of the dielectric grating is 25-65°.

4. The spectral sensor based on ultra-narrowband out-of-plane surface lattice resonance mode according to claim 1, characterized in that: The material of the V-shaped metal nanoantenna array is silver, aluminum, sodium or platinum; the thickness d of the V-shaped metal nanoantenna is 50-100nm, the height H is 250-450nm, and the asymmetric factor β is 0-1.

5. The method for preparing a spectrum sensor based on an ultra-narrow band out-of-plane surface lattice resonance mode according to claim 1, characterized in that: The following steps are involved: The dielectric grating is prepared on the upper surface of the substrate by interference lithography, and then silver of the same thickness is evaporated on both sides of the dielectric grating at a predetermined tilt angle by vacuum thermal evaporation to form a V-shaped metal nanoantenna.

6. A detection system based on the spectral sensor, characterized in that: The spectral sensor based on the ultra-narrowband out-of-plane surface lattice resonance mode as described in claim 1 is encapsulated in a transparent medium cavity, the transparent medium cavity is fixed on a rotating platform rotating around the z-axis, and a medium outlet and a medium inlet are connected to the transparent medium cavity. The incident light source irradiates the spectral sensor in the transparent medium cavity after passing through a semi-transparent and semi-reflective mirror. After the spectral sensor is excited, the light wave carrying the resonance signal is reflected by the semi-transparent and semi-reflective mirror, and then transmitted to the spectrometer through the optical fiber.

7. Use of the spectral sensor according to claim 1 or the detection system according to claim 6 in medium refractive index detection.

8. Use of the spectral sensor according to claim 1 or the detection system according to claim 6 in medium concentration detection.

9. The use according to claim 7 or 8, characterized in that The medium is gas or liquid.

10. The use according to claim 7 or 8, characterized in that: The method for detecting the refractive index or concentration of a medium using the detection system comprises the following steps: Step 1, fix the angle of the rotating platform, turn on the incident light source, and the spectrometer detects the reflection valley of the spectrum sensor based on the SLR mode, and records the central resonance wavelength λ1 of the reflection valley. Preferably, the incident angle θ of the incident light source is 0° to 30°; Step 2, taking standard samples of different concentrations or different refractive indices and sequentially filling them into the transparent medium cavity, the spectrometer sequentially detects the reflection valley of the spectral sensor based on the SLR mode, records the central resonance wavelength λ2 of the reflection valley, calculates the overall offset Δλ=λ2-λ1 of the reflection valley, and establishes a standard curve of concentration-Δλ or refractive index-Δλ; Step 3: Fill the sample to be tested into the transparent medium cavity, and the spectrometer detects the reflection valley of the spectrum sensor and records the central resonance wavelength λ of the reflection valley. ′ , calculate the overall offset Δλ of the reflection valley ′ =λ ′ -λ1, Δλ ′ Substitute the standard curve to solve the concentration or refractive index of the sample to be tested.

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