Optical resonance peak Q value regulation method and application

Abstract

The method includes: 1) obtaining the inherent property parameters of the target system and / or the environmental refractive index change value Δn; the target system is a multi-resonant coupled system and / or an asymmetric BIC system; 2) constructing an equation based on the environmental refractive index change value Δn and / or the obtained inherent property parameters in step 1); when the target system is a multi-resonant coupled system, constructing a relationship between the resonance peak Qr value and the environmental refractive index change value Δn. This invention belongs to the field of optical physics, and particularly relates to a method for controlling the Q value of an optical resonance peak and its application. When the target system is an asymmetric BIC system, the radiation quality factor law of the asymmetric BIC system is used; 3) calculating based on equations 1 and 2, and adjusting or changing the asymmetry factor α of the environmental refractive index change value Δn based on the calculation results of the Qr value and the adjustment purpose to achieve the control of the Qr value. This invention can control the Qr value through changes in the environmental refractive index.

Description

Technical Field

[0001] This invention belongs to the field of optical physics, and in particular relates to a method for controlling the Q value of an optical resonance peak and its application. Background Technology

[0002] Optical physics is the science that studies the interaction between light and matter. Light, as an electromagnetic wave, exhibits phenomena such as propagation, reflection, refraction, diffraction, and scattering, all influenced by the properties of matter. These fundamental physical processes form the basis for the operation of optical sensors and systems. The wave nature of light, particularly its frequency and wavelength, can be used to precisely measure the optical properties of matter, including refractive index, absorption coefficient, and scattering characteristics.

[0003] Optical sensors utilize the physical properties of light to detect and quantify changes in external factors. They are widely used in environmental monitoring, chemical analysis, materials science, and biomedical engineering. Compared to traditional electrochemical sensors, optical sensors offer higher sensitivity, faster response times, and better interference resistance. With the development of micro-nano fabrication technology, the size of optical sensors is continuously shrinking and their integration is constantly increasing, making portable and low-cost sensing devices possible.

[0004] Biosensing technology is an extension of the application of optical sensors in the biological field. The recognition and detection of biomolecules are crucial for disease diagnosis, environmental monitoring, and food safety. However, traditional biosensing methods often rely on complex labeling processes and large analytical equipment, which limits their application scope and convenience. For example, the traditional plasmonic SPR configuration is one of the most commonly used commercial biosensing platforms, but its complex oblique-incident prism coupling and probe optical path system results in large and expensive devices, making large-scale application and integration difficult. Therefore, developing a novel biosensing technology that enables label-free, high-sensitivity, rapid response, and portable detection has become an urgent need for research and industry.

[0005] Currently, visible / near-infrared optical metasurface biosensors are a type of universal label-free biosensor with wide applications in both scientific research and daily life. While achieving label-free operation, this still requires the use of equipment such as supercontinuum light sources and large spectrometers for optical sensing testing, resulting in complex and bulky testing systems that lack portability and versatility. Furthermore, to improve sensing performance, current mainstream research focuses on using complex designs and precise fabrication to increase the Q-value (Qr value) of the resonance peak (resulting in a narrower linewidth). This further increases fabrication costs and testing difficulty, requiring more precise and expensive testing equipment, deviating from the goals of practical application and integration of optical biosensing systems. In recent years, the concept of spectral imaging biosensing combining high-Q optical metasurfaces has shown the possibility of further integration of optical biosensing systems. However, the matching problem between the dynamic high-Q narrow-linewidth resonance peak and the static specific wavelength light source remains prominent during the sensing process. The problems mainly stem from three sources: First, the contradiction between a fixed illumination source frequency and a resonant frequency that shifts with the measured object easily leads to frequency mismatch, resulting in irregular responses. Second, high-Q optical metasurfaces have low robustness to fabrication defects, further causing resonant frequency shifts and mismatches. Third, the bandwidth of the illumination source and the resonant bandwidth are mismatched. For example, the resonant bandwidth of high-Q sensors is typically 1-5 nm, while the bandwidth of typical illumination sources is above 5 nm. This can cause response failure when the high-Q resonant frequency shifts. These frequency and bandwidth mismatches not only reduce the reliability of the imaging signal but also make chip fabrication highly dependent on high-precision processing equipment, greatly restricting the practicality and versatility of integrated imaging optical sensors. To address the above issues, existing technologies offer few solutions. Currently, the only relatively effective method is to utilize bound states in the continuous domain (BIC) to design and fabricate a series of two-dimensional BIC metasurface array structures with different asymmetric coefficients to perform pixel-wise scanning of the Q value from low to high (referred to as the "Q-scanning" scheme). This ensures that during sensor operation, the resonant peak of the array always has a good match with the light source wavelength. For example, CN202280010383.3 describes a sensor component with an optical metasurface film. As mentioned earlier, this technical solution requires designing specific sensor pixel arrays and metasurface arrays, achieving Qr value adjustment through the construction of complex arrays. Similarly, CN202110970414.7 describes an all-dielectric metasurface refractive index sensor and its fabrication method, which also improves sensor performance through a dielectric metasurface structure unit array. The overall design process is complex, its versatility is very limited, and its performance is significantly restricted by the array. Furthermore, in frequency-shifting sensing mechanisms, expensive narrowband tunable light sources are required for alignment with high Q-value signals.This "Q-value scanning" scheme based on two-dimensional BIC metasurfaces further increases the reliance on high-precision preparation, making the processing steps more complex, increasing costs, and making large-scale application more difficult.

[0006] Therefore, this invention aims to achieve efficient adjustment of the Qr value of the resonance peak for any existing metasurface array structure, mainly through the control of the external environment of the system. This will significantly improve the performance of optical sensors and realize a truly integrated and practical high-Q-value optical metasurface biosensing system. Summary of the Invention

[0007] To address the challenges of frequency and bandwidth mismatch between sensors and light sources caused by high Q values ​​in current optical sensing systems, especially optical biosensing systems, during practical applications, which leads to significant design, modulation, and correction difficulties, high costs, large device size, and poor usability, this invention provides a method for controlling the Qr value of optical resonance peaks, and its application in optical sensing systems and / or optical sensor devices, particularly biosensing systems and / or biosensor devices. This method addresses the issues of high-precision tunable narrowband light sources and high-resolution spectrometers, which drastically increase system costs. Furthermore, existing techniques are not universally applicable to the design, modulation, and correction of optical biosensors.

[0008] The main objective of this invention is:

[0009] First, it can achieve efficient control of the Qr value by changing the refractive index of the environment;

[0010] Second, the Qr value is highly controllable. The Qr value of the target system can be increased or decreased according to the requirements to approach the optimal Qr value or even completely coincide with the optimal Qr value, thus achieving the critical coupling state.

[0011] Third, it can be effectively applied to all existing optical sensing systems and / or optical sensor devices, and realize an integrated high-Q optical sensing system.

[0012] To achieve the above objectives, the present invention adopts the following technical solution.

[0013] A method for controlling the Q value of an optical resonance peak.

[0014] The method includes:

[0015] 1) Obtain the inherent property parameters of the target system and / or the environmental refractive index change value Δn;

[0016] The target system is a multi-resonant coupling system and / or an asymmetric BIC system;

[0017] The multi-resonant coupling system has a resonator 1 and a resonator 2. The natural frequency of the resonator 1 redshifts as Δn increases, while the natural frequency of the resonator 2 does not change with Δn. In the zero decoupling state, the frequencies of the resonator 1 and the resonator 2 are equal. The inherent loss of the resonator 1 does not change with Δn, while the inherent loss of the resonator 2 increases as Δn increases.

[0018] The asymmetric BIC system comprises two nanoparticle metasurfaces with different diameters, heights, materials, and spatial displacements.

[0019] 2) Construct the associated Qr value based on the environmental refractive index change value Δn and / or the obtained intrinsic property parameters from step 1); when the target system is a multi-resonant coupled system, the obtained intrinsic property parameters include: the energy support frequency ω of the coupled system, the initial attenuation coefficient γ′2 of the resonator 2 in the zero-decoupling state, the coupling strength g between the resonator 1 and the resonator 2, and the Rabi splitting Ω. R The sensitivity S1 of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn; the sensitivity S2 of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn; the natural frequency ω1 of harmonic oscillator 1; the natural frequency ω2 of harmonic oscillator 2; and the nonradiative attenuation coefficient γ. n ;

[0020] The relationship between the resonance peak Qr value and the change in environmental refractive index Δn is expressed as Equation 1 below:

[0021] Formula 1:

[0022] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r The value is given by ω, which is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; and g is the coupling strength between resonator 1 and resonator 2, Ω. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n The non-radiative attenuation coefficient;

[0023] When the target system is an asymmetric BIC system, the acquired intrinsic property parameters include: asymmetry factor α;

[0024] According to the following formula, Equation 2, the radiation quality factor of the asymmetric BIC system:

[0025] Equation 2: Q r =a+bα -2 ;

[0026] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r Values, where α is an asymmetric factor, and both a and b are represented by at least two points in the data Q. r Substituting α into the calculation results;

[0027] 3) Based on equations 1 and 2 from step 2) above:

[0028] When the target system is a multi-resonant coupled system, the inherent property parameters are substituted into Equation 1 for calculation, and the environmental refractive index change value Δn is adjusted by the calculation result of Qr value and the adjustment purpose to achieve the control of Qr value;

[0029] The method of adjusting the environmental refractive index change value Δn includes adjusting and / or replacing the liquid system or atmospheric environment in which the target multi-resonance coupling system is located;

[0030] When the target system is an asymmetric BIC system, the nanoparticles of the asymmetric BIC system are selectively modified according to the adjustment purpose to change the asymmetry factor α in order to control the Qr value.

[0031] When the target system simultaneously possesses the characteristics of a multi-resonant coupled system and an asymmetric BIC system, the Qr value can be controlled by changing the environmental refractive index change value Δn and / or the asymmetry factor α using at least one of the above methods.

[0032] As a preferred option

[0033] Step 2) The relationship between the resonant peak Qr value and the change in environmental refractive index Δn is constructed by combining the critical coupling mechanism with Equation 1, Equation 3 (the coupling strength modification formula between resonator 1 and resonator 2) and Equation 4 (the conversion coefficient calculation formula).

[0034] Formula 3: g n = g × Δn(S1 - S2)

[0035] In Equation 3: g n S1 is the result of the coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 after correction by the environmental refractive index change value Δn, where Δn is the environmental refractive index change value, S1 is the sensitivity of the intrinsic frequency of harmonic oscillator 1 to the environmental refractive index change value Δn, and S2 is the sensitivity of the intrinsic frequency of harmonic oscillator 2 to the environmental refractive index change value Δn.

[0036] Equation 4: m = 5Δn(S1 - S2)

[0037] In the formula: m is the conversion coefficient of the intrinsic attenuation coefficient difference passively generated by the introduction of the difference in intrinsic frequency changes of resonator 1 and resonator 2 during the sensing process in the target multi-resonant coupling system; Δn is the change in ambient refractive index; S1 is the sensitivity of the intrinsic frequency of resonator 1 to the change in ambient refractive index Δn; and S2 is the sensitivity of the intrinsic frequency of resonator 2 to the change in ambient refractive index Δn.

[0038] As a preferred option

[0039] After combining Equation 1 with Equations 3 and 4 and making corrections, we obtain Equation 5:

[0040] Formula 5:

[0041] In the formula: Q r ω is the radiation quality factor, i.e., the resonant peak Qr value; ω is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; m is the conversion coefficient of the difference in intrinsic attenuation coefficient passively generated by the difference in the intrinsic frequency changes of resonators 1 and 2 during the sensing process in the target multi-resonant coupled system; g is the radiation quality factor, i.e., the resonant peak Qr value; ω is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; m is the conversion coefficient of the difference in intrinsic attenuation coefficient changes passively generated by the difference in the intrinsic frequency changes of resonators 1 and 2 during the sensing process; g is the energy support frequency in the target multi-resonant coupled system. n The coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 is the result after correction for the environmental refractive index change Δn, Ω. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n This is the non-radiative attenuation coefficient.

[0042] As a preferred option

[0043] When the target system is an asymmetric BIC system or contains asymmetric BIC system characteristics, the control requirements are determined according to the resonant peak absorbance expression of Equation 6, and the Qr value is controlled by Equation 2.

[0044] Formula 6:

[0045] In the formula: Abs is the absorbance, x is the maximum absorbance of the system and is calculated by substituting 1, Q r Q is the radiation quality factor. n ω is the nonradiative quality factor, and ω is the frequency of any harmonic oscillator in the zero-decoupling state. r This is the natural oscillation frequency of the system when there are no losses.

[0046] This process is performed when the target system contains asymmetric nanostructures NP-a and NP-b.

[0047] The nanostructures NP-a and NP-b have different structural widths and / or structural radii and / or structural heights and / or relative spatial positions, wherein the structural width and / or structural radius and / or structural height of nanostructure NP-a is greater than the structural width and / or structural radius and / or structural height of nanostructure NP-b.

[0048] The selective modification treatment involves modifying the surface of nanostructures NP-a and / or NP-b to create local refractive index changes, which can be achieved through deposited oxides or biomolecule modifications.

[0049] As a preferred option

[0050] The local refractive index change and radiation quality factor Q resulting from the surface modification of the nanostructure NP-a are related. r Negative correlation;

[0051] The local refractive index change and radiation quality factor Q resulting from the NP-b surface modification of the nanostructure r They are positively correlated.

[0052] Application of a method for controlling the Q value of an optical resonance peak

[0053] The method is used for modulation and / or design and / or modification of optical sensing systems and / or optical sensor devices.

[0054] As a preferred option

[0055] The optical sensing system and / or optical sensing device includes a biosensing system and / or a biosensor device.

[0056] For the technical solution of this invention, the most crucial aspects are the construction of Equation 1 and the application of Equation 2. In traditional Q-switching systems, this is achieved by altering the microscopic physical structure of the system, and the process involves a series of trial and error attempts to ultimately reach a microscopic structure system with the optimal Qr value. However, for the technical solution of this invention, the scheme based on Equation 1 effectively converts the real part change of refractive index into the imaginary part change of resonant frequency in the visible / near-infrared band, thereby adjusting the Qr value and moving beyond the traditional sensing approach where the environmental refractive index change Δn only corresponds to the real part change of resonant frequency. Equation 2 adjusts the Qr value by selectively modifying the asymmetric structure to change the local environmental refractive index. This differs from conventional sensing processes that involve non-selective, uniform modification of nanostructures. Instead, it is based on the relationship between the Qr value and the asymmetry factor α in Equation 2, selecting one nanostructure from a binary asymmetric structure for modification and sensing, thus effectively changing the Qr value during the sensing process. Through Equations 1 or 2, combined with the corrections of Equations 3-4 and Equation 6, Qr rapidly approaches Qn. Since the system absorption reaches 100% when Qr = Qn, the system absorption will be greatly enhanced as Qr rapidly approaches Qn. This enables the effective change of the Qr value through the refractive index of the environment, resulting in a significant change in the intensity of the system feedback signal. Consequently, an integrated platform that is highly compatible with various light sources is achieved.

[0057] Equation 1 was derived through a series of derivations. First, based on... Based on the fundamental formula, we derive the eigensols for a strongly coupled system with two harmonic oscillators (i.e., containing harmonic oscillator 1 and harmonic oscillator 2) using the 2×2 Hamiltonian algorithm, as shown in equation S1 below:

[0058] Formula S1:

[0059] In the formula: H is the Hamiltonian, ω1 is the natural frequency of resonator 1, ω2 is the natural frequency of resonator 2, γ1 is the decay rate of resonator 1, γ2 is the decay rate of resonator 2, and i is a purely imaginary number and is defined as i 2 =-1, where g is the coupling strength between harmonic oscillator 1 and harmonic oscillator 2.

[0060] The eigenenergy relation can be derived from the above algorithm S1 as follows: S2

[0061] Formula S2:

[0062] In the formula: ω ± Let ω1 be the natural frequency of the two harmonic oscillator system, ω2 be the natural frequency of harmonic oscillator 1, ω1 be the decay rate of harmonic oscillator 1, γ2 be the decay rate of harmonic oscillator 2, and i be a purely imaginary number defined as i2 =-1, where g is the coupling strength between harmonic oscillator 1 and harmonic oscillator 2.

[0063] When ω1 = ω2, the zero decoupling position is reached, and the Rabi splitting is obtained as follows: S3:

[0064] Formula S3:

[0065] Where: Ω R For Rabi splitting, γ1 is the decay rate of resonator 1, γ2 is the decay rate of resonator 2, and g is the coupling strength between resonator 1 and resonator 2.

[0066] A strongly coupled system is achieved when the Rabi splitting condition is greater than 0. At this point, we introduce the change in ambient refractive index Δn, causing the system to transition from a zero-decoupling state to a non-zero-decoupling state (ω1 > ω2). This introduces frequency shifts in both energy levels, specifically the frequency changes Δω1 and Δω2 of harmonic oscillator 1 and harmonic oscillator 2, respectively. Equation S3 is then extended to the following set of equations S4 to S7:

[0067] Formula S4: Δω1=S1Δn; Δω2=S2Δn;

[0068] Formula S5: ΔΔω=Δn(S1-S2);

[0069] Formula S6:

[0070] Formula S7: ΔΔγ=Δγ1-Δγ2;

[0071] In the above formula set: Δω1 is the frequency change of resonator 1, Δω2 is the frequency change of resonator 2, Δn is the change in ambient refractive index, S1 is the sensitivity of the intrinsic frequency of resonator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the intrinsic frequency of resonator 2 to the change in ambient refractive index Δn, Δω is the difference in frequency changes between resonator 1 and resonator 2, g is the coupling strength between resonator 1 and resonator 2, and i is a purely imaginary number defined as i 2 =-1, Ω R For Rabi splitting, γ′1 is the initial attenuation coefficient of resonator 1 in the zero decoupling state, γ′2 is the initial attenuation coefficient of resonator 2 in the zero decoupling state, ΔΔγ is the difference between the attenuation rate changes of resonator 1 and resonator 2, Δγ1 is the attenuation rate change of resonator 1, and Δγ2 is the attenuation rate change of resonator 2.

[0072] Therefore, substituting the difference in eigenfrequencys in the strongly coupled system caused by the change in environmental refractive index into the Rabi splitting formula, we obtain the perturbation formula S6 mentioned above. Here, we assume that in this strongly coupled system, ω1 is highly sensitive to the change in environmental refractive index Δn, while ω2 is conversely, very insensitive to the change in environmental refractive index Δn, i.e., S1 >> S2. Then, Δγ can be derived as equations S8 and S9:

[0073] Formula S8:

[0074] Formula S9:

[0075] In equations S8 and S9 above: Δγ is the difference in the decay rate changes of resonator 1 and resonator 2, g is the coupling strength between resonator 1 and resonator 2, and Ω R For Rabi splitting, ΔΔω is the difference in frequency change between resonator 1 and resonator 2, γ′1 is the initial attenuation coefficient of resonator 1 in the zero-decoupling state, γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state, ω1 is the natural frequency of resonator 1, ω2 is the natural frequency of resonator 2, and i is a purely imaginary number defined as i 2 =-1. Since ΔΔω and ω1-ω2 are both positive, according to formula S8, ΔΔγ must be negative. If for harmonic oscillator 1, it has already produced a significant ΔΔω, then its Δγ1 is very small, even close to 0. This means that for harmonic oscillator 2, whose Δω2 is extremely small, its Δγ2 will necessarily increase significantly, that is, the attenuation coefficient will increase significantly. This completes the transformation of the change in the real part of the refractive index into the change in the imaginary part of the resonant frequency, that is, linking Δn with Δγ. In summary, in a strongly coupled system of two harmonic oscillators, as long as the following two conditions are met, the change in the real part of the environmental refractive index can be transformed into a considerable change in the imaginary part of the resonant frequency, thus obtaining the following formulas S10 and S11:

[0076] Formula S10: ΔΔω>>0(Δω1>>Δω2);

[0077] Formula S11: ΔΔγ<<0 (Δγ1<<Δγ2);

[0078] In the formula: Δω is the difference in frequency change between resonator 1 and resonator 2, Δω1 is the frequency change of resonator 1, Δω2 is the frequency change of resonator 2, Δγ is the difference in attenuation rate change between resonator 1 and resonator 2, Δγ1 is the attenuation rate change of resonator 1, and Δγ2 is the attenuation rate change of resonator 2.

[0079] Based on this condition, we can design specific nano-optical structures to achieve our goals. Furthermore, since the total attenuation coefficient γ is actually determined by the radiation attenuation coefficient γ... rNon-radiative attenuation coefficient γ n It consists of two parts, as shown in equation S12 below:

[0080] Equation S12: γ=γ r +γ n ;

[0081] In the formula: γ is the total attenuation coefficient, γ r γ is the radiation attenuation coefficient. n This is the non-radiative attenuation coefficient.

[0082] Where, γ n The attenuation coefficient is primarily determined by the materials that make up the nanostructure and is not affected by changes in the refractive index of the environment. Therefore, in the aforementioned strongly coupled system, the change in the attenuation coefficient caused by the change in the environmental refractive index Δn is mainly due to the radiation attenuation coefficient γ. r At this point, according to condition S11, we assume that the change in attenuation coefficient Δγ1 of harmonic oscillator 1 is zero. Then, for the change in attenuation coefficient of harmonic oscillator 2, we can obtain the following equations S13 and S14:

[0083] Equation S13: γ′2 + Δγ2 = γ r +γ n ;

[0084] Formula S14: γ r =γ′2-ΔΔγ-γ n ;

[0085] In the formula: γ′2 is the initial decay coefficient of the resonator 2 in the zero-decoupling state, Δγ2 is the change in the decay rate of the resonator 2, and γ r γ is the radiation attenuation coefficient. n Δγ is the non-radiative attenuation coefficient, and Δγ is the difference in the attenuation rate changes of harmonic oscillator 1 and harmonic oscillator 2.

[0086] Based on the relationship between the attenuation coefficient and the quality factor Q Formula 14 can be transformed into the expression S15 for the radiation Q value: Formula S15:

[0087] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r Value, ω is the energy support frequency in the strongly coupled system, γ′2 is the initial decay coefficient of resonator 2 in the zero-decoupling state, Δγ is the difference in the decay rate changes of resonator 1 and resonator 2, γ n This is the non-radiative attenuation coefficient.

[0088] Therefore, we can write Δn and Q. r The direct relationship formula S16, which is also the formula 1 of this invention:

[0089] Equation S16 (Equation 1):

[0090] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r The value is given by ω, which is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; and g is the coupling strength between resonator 1 and resonator 2, Ω. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n This is the non-radiative attenuation coefficient.

[0091] This formula represents the novel Q-switching mechanism (resonance peak Qr value adjustment mechanism) proposed in this invention. It can transform changes in the real part of the refractive index into changes in the resonant Q value (resonance peak Qr value). However, simple Q value changes mainly result in changes in signal bandwidth. To make the signal changes more significant, we need to combine the refractive index Q-switching mechanism with the critical coupling mechanism, using the following equation S17 (Equation 3):

[0092] Equation S17 (Equation 3):

[0093] In the formula: Abs is the absorbance, x is the maximum absorbance of the system and is calculated by substituting 1, Q r Q is the radiation quality factor. n ω is the nonradiative quality factor, and ω is the frequency of any harmonic oscillator in the zero-decoupling state. r Let be the natural oscillation frequency of the system when there are no losses.

[0094] When the radiation quality factor Q r With non-radiative quality factor Q n When the values ​​are equal, the system reaches its maximum absorption x, which is the critical coupling. Here, we set x to 1. Combining formulas S16 and S17, we can achieve significant simultaneous changes in signal bandwidth and intensity near the critical coupling state through Q-switching of the refractive index, which is simply called the near-critical coupling Q-switched sensing mechanism (QSCC).

[0095] To make the calculations more realistic, we introduce two corrections. 1: The coupling strength g should also be related to the refractive index change Δn, g n= g × Δn(S1-S2); 2: Due to the existence of other radiation leakage channels in practical applications, ΔΔγ cannot be fully involved in the QSCC sensing process. Therefore, we set a ΔΔγ conversion coefficient m, representing the attenuation coefficient variation part involved in the QSCC sensing mechanism. Furthermore, this conversion coefficient increases with the increase of Δn: m = 5Δn(S1-S2). Thus, the corrected refractive index Q-switching formula is Equation S18 (Equation 4):

[0096] Equation S18 (Equation 4):

[0097] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r Value, ω is the energy support frequency in the strongly coupled system, γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state, m is the conversion coefficient of the difference in intrinsic attenuation coefficient passively generated by the target multi-resonant coupled system due to the introduction of the difference in the intrinsic frequency changes of resonators 1 and 2 during the sensing process, and g n The coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 is the result after correction for the environmental refractive index change Δn, and the correction is g. n = g × Δn(S1 - S2), Ω R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n This is the non-radiative attenuation coefficient.

[0098] With further modifications to Equation S17 (Equation 3), the calculated results will be closer to the actual values ​​and have a very high degree of confidence.

[0099] The beneficial effects of this invention are:

[0100] This invention achieves control of the Qr value through a very simple method of changing the environmental refractive index. It can increase or decrease the Qr value of the target system as needed to approach or even completely coincide with the optimal Qr value. Furthermore, the theoretical calculation results have extremely high confidence. Since the technical solution of this invention is not limited to arbitrary materials and / or structures, it can be effectively applied to the modulation, design, and modification of all existing optical sensing systems and / or optical sensor devices. Attached Figure Description

[0101] Figure 1 The structural parameters of the 3D plasmonic BIC metasurface designed by FDTD simulation in Example 1 are shown below.

[0102] Figure 2 The three-dimensional spectral results obtained by changing the refractive index of the environment based on FDTD simulation design in Example 1;

[0103] Figure 3 The results show the reflectance characterization at different glycerol concentrations in Example 1.

[0104] Figure 4 This is a graph showing the relationship between peak intensity and wavelength variation in Example 1;

[0105] Figure 5 This is a graph showing the trend of Qr value and full width at half maximum (FWHM) as a function of refractive index in Example 1.

[0106] Figure 6 This is a graph showing the trend of Qr value as a function of refractive index based on Equation 1 in Example 1;

[0107] Figure 7 This is a graph showing the trend of absorption intensity as a function of refractive index based on Equation 1 in Example 1;

[0108] Figure 8 This is a graph showing the trend of Qr value as a function of refractive index based on Equation 5 in Example 1;

[0109] Figure 9 This is a graph showing the trend of absorption intensity as a function of refractive index based on Equation 5 in Example 1;

[0110] Figure 10 This is a schematic diagram of the near-critical coupled Q-switched biosensor physical model based on a strongly coupled system according to the present invention.

[0111] Figure 11 This is a schematic diagram of the quasi-BIC metasurface on the gold substrate in Example 2;

[0112] Figure 12 This is a graph showing the relationship between absorption intensity and wavelength under critical coupling conditions in Example 2;

[0113] Figure 13 This is a graph showing the relationship between absorption intensity and wavelength after the critical coupling is broken in Example 2;

[0114] Figure 14 This is a graph showing the relationship between absorption intensity and wavelength under critical coupling conditions after changing the NP-a surface structure in Example 2;

[0115] Figure 15 This is a graph showing the relationship between absorption intensity and wavelength when the critical coupling is broken after the NP-a surface structure is changed in Example 2.

[0116] Figure 16 This is a graph showing the relationship between absorption intensity and wavelength under critical coupling conditions after changing the NP-b surface structure in Example 2;

[0117] Figure 17 This is a graph showing the relationship between absorption intensity and wavelength when the critical coupling is broken after the NP-b surface structure is changed in Example 2.

[0118] Figure 18 This is a graph showing the relationship between the environmental refractive index and the resonant wave in Example 2;

[0119] Figure 19 In Example 2, the relationship between the refractive index difference and absorption intensity between the two nanoparticles was changed. Figure 1 ;

[0120] Figure 20 In Example 2, the relationship between the refractive index difference and absorption intensity between the two nanoparticles was changed. Figure 2 ;

[0121] Figure 21 This is a schematic diagram of the fabrication process of the 3D plasmonic BIC metasurface designed in Example 1;

[0122] Figure 22 This is a schematic diagram of the volumetric sensing performance of the three-dimensional BIC metasurface simulation in Example 3;

[0123] Figure 23 This is a schematic diagram of the three-dimensional BIC metasurface sensing module based on the QSCC sensing mechanism in Example 3 and its surface sensing performance in the VIS band. Detailed Implementation

[0124] The present invention will be further described clearly and in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0125] In the description of this invention, it should be understood that the terms "thickness," "upper," "lower," "horizontal," "top," "bottom," "inner," "outer," "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified, and "several" means one or more.

[0126] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0127] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0128] Example 1

[0129] This embodiment aims to verify Formulas 1 and 3-6 of the present invention.

[0130] First, a novel 3D plasmonic BIC metasurface was designed using FDTD simulation, and its performance in sensing was calculated. Its structural parameters are as follows: Figure 1 As shown, the diameters of gold particles 1 and 2 in this metasurface are D1 = D2 = 320 nm, the depths are Z1 = 60 nm and Z2 = 200 nm, and the period is P = 800 nm. The substrate is resin (Resin, refractive index 1.56); the upper gold layer is titanium dioxide (TiO2), with a refractive index of 2.2 and a thickness of 80 nm. The gold layer thickness is 50 nm, and the refractive index of the materials is fitted using data from the Johnson & Christy material library. By changing the ambient refractive index in FDTD, we obtain the following... Figure 2 The three-dimensional spectral results show that qBIC1 still exhibits a predominantly frequency shift, redshifting with increasing refractive index, while its peak intensity remains relatively unchanged, satisfying condition one (Δw1>>0, Δγ1≈0). In contrast, qBIC2 shows a significant increase in peak intensity and a wider full width at half maximum (FWHM) with increasing refractive index, while exhibiting a very small frequency shift, satisfying condition two (Δw2≈0, Δγ2>>0). Therefore, the simulated qBIC2 directly verifies the QSCC sensing mechanism.

[0131] The simulation calculations described above were further verified in specific experiments.

[0132] We fabricated the aforementioned 3D plasmonic BIC metasurface using a nanoimprint binary anodic alumina process, exhibiting the same microscopic physical structure characteristics. The specific fabrication process is as follows (process as shown). Figure 21 As shown in the example, this example uses an 800nm ​​period fabrication process:

[0133] First, a nickel film with periodic nanopillars (T = 800 nm) was used at 15 kN·cm. -2 Imprinting was performed under pressure for 3 minutes to form an array of nanodots with a spacing of 800 nm on the surface of an aluminum sheet. The imprinted aluminum sheet was then anodized at 320 V and 30 °C for 2 hours in a mixed solution (4 g citric acid, 200 mL ethanol, 200 mL H₂O, and 10 mL 0.1 wt% H₃PO₄) to obtain arranged nanopores (a-pores). The aluminum sheet was then immersed in a 5 wt% H₃PO₄ solution for 2 hours to expand these a-pores. A thin TiO₂ layer was then deposited within the a-pores using an ALD system to protect them from chemical corrosion. ALD was performed at 150 °C with a cycle time of 0.5 s C₁₂H₂₈O₄Ti, 8 s N₂ purging, 0.1 s H₂O, and 8 s N₂ purging, for 70 cycles. The top surface of the BP-AAO template was then milled using an ion milling system (IM4000plus) to ensure the b-pores were fully opened. A PMMA solution was coated onto the surface of the BP-AAO template, and the unoxidized aluminum sheet was removed using a mixed solution (1.5 wt% CuCl2 and 53.2% HCl). The PMMA layer was then dissolved in acetone. Finally, the BP-AAO template was immersed in 0.1 M NaOH solution at room temperature for 30 minutes to generate new pores (b-pores) at the quadruple connections of the a-pores. The BP-AAO template was then transferred to a silicon wafer in water.

[0134] A silicon wafer with a BP-AAO template was placed in an inductively coupled plasma etching system (Leuven ICP, HAASRODE-E200A) and etched for 20 seconds using a mixed gas of CF4 and SF6 at 20°C and 8 mT VAT. The blocking layer of the a-hole was then removed using ion beam tilting milling. A 10 nm thick Cr layer was then deposited as a sacrificial layer using physical vapor deposition (PVD). After the BP-AAO template was removed, two layers of Cr particles were observed. A second ICP etching was then performed using the same gas formulation, but for 24 seconds, to generate a 3D silicon-based nanostructure. A 50 nm Au film was deposited on the 3D silicon-based nanostructure, followed by a UV-cured NOA83 resin coating. The three-dimensional nanostructure was then peeled off from the silicon wafer using a direct lift-off method. Finally, a three-dimensional BIC metasurface was formed by PVD deposition of a TiO2 layer, with the coupling conditions controlled by varying the TiO2 thickness.

[0135] The diameters of nanoparticles 1 and 2 in the metasurface are D1 = D2 = 320 nm, the depths are Z1 = 60 nm and Z2 = 200 nm, and the period is P = 800 nm. Reflectivity was characterized by changing the refractive index Δn of the environment by introducing different glycerol concentrations into the microfluidic system. The results are as follows: Figure 3As shown. You can see that, Figure 3 The spectrum obtained from the experimental test and Figure 2 The simulated spectra are highly consistent. qBIC1 mainly exhibits a frequency shift, with a redshift as the refractive index increases, while its peak intensity does not change significantly, satisfying condition one (Δw1>>0, Δγ1≈0). qBIC2, on the other hand, shows a significant increase in peak intensity and a wider full width at half maximum (FWHM) as the refractive index increases, with a very small frequency shift, satisfying condition two (Δw2≈0, Δγ2>>0).

[0136] Further, based on experimental characterization, the peak intensity and wavelength changes of qBIC2 were extracted to obtain, as follows: Figure 4 The schematic diagram shows that the peak intensity increases sharply with increasing refractive index, while the wavelength does not change significantly (<3nm). The absolute intensity refractive index sensitivity reaches 561% / RIU, and the relative intensity refractive index sensitivity reaches 1500% / RIU. The Qr value and FWHM of qBIC2 extracted based on experimental characterization show the trend as a function of refractive index. Figure 5 As shown, it decays rapidly with increasing refractive index and approaches Q. n The value represents the approaching critical coupling state. Simultaneously, the FWHM gradually widens, reflecting an increase in radiation loss.

[0137] Furthermore, based on the following equations 1 and 6:

[0138] Formula 1:

[0139] In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r The value is given by ω, which is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; and g is the coupling strength between resonator 1 and resonator 2, Ω. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n The non-radiative attenuation coefficient;

[0140] Formula 6:

[0141] In the formula: Abs is the absorbance, x is the maximum absorbance of the system and is calculated by substituting 1, Q r Q is the radiation quality factor. n ω is the nonradiative quality factor, and ω is the frequency of any harmonic oscillator in the zero-decoupling state. rThis is the natural oscillation frequency of the system when there are no losses.

[0142] Substitute the experimental parameters: γ n =2.5meV,ω=97.8meV,g=27.2meV,Ω R =46meV, S1=300meV / RIU, S2=0meV / RIU, x=1, γ′2 are 2.5, 2.7, 2.9, 3.1, 3.3, 3.5meV respectively (corresponding to the initial decay rate γ). r0 The γ values ​​are 0, 0.2, 0.4, 0.6, 0.6, 0.8, and 1.0; when γ r0 =0 means the initial state of the system is BIC state. The results are as follows: Figure 6 and Figure 7 The results are shown.

[0143] It can be observed that Q r It decays rapidly with increasing refractive index change. However, smaller γ... r0 Make Q r The curve rises overall, and has a higher initial Q when Δn = 0. r The absorption peak intensity increases rapidly with the increase of the refractive index value, and when Q... r Approaching Q n At that time, it approaches saturation. Furthermore, smaller γ... r0 This results in a lower initial absorption intensity, leading to faster intensity changes and a wider range of intensity variations. Therefore, introducing radiation loss suppression mechanisms, such as BIC, can improve the performance of QSCC sensors in strongly coupled systems.

[0144] Based on the above results and... Figure 5 The comparison reveals that the trend of Qr value changes is similar to... Figure 1 The results show a high degree of agreement, but the refractive index decreases rapidly as it increases. The effectiveness of Equation 1 of this invention is verified by the Qn value, which is the critical coupling state.

[0145] Based on this, Equation 1 is further modified using Equations 3 and 4 to obtain Equation 5:

[0146] Formula 3: g n = g × Δn(S1 - S2)

[0147] In Equation 3: g n S1 is the result of the coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 after correction by the environmental refractive index change value Δn, where Δn is the environmental refractive index change value, S1 is the sensitivity of the intrinsic frequency of harmonic oscillator 1 to the environmental refractive index change value Δn, and S2 is the sensitivity of the intrinsic frequency of harmonic oscillator 2 to the environmental refractive index change value Δn.

[0148] Equation 4: m = 5Δn(S1 - S2)

[0149] In Equation 4: m is the conversion coefficient of the intrinsic attenuation coefficient difference passively generated by the target multi-resonant coupling system due to the introduction of the difference in intrinsic frequency changes generated by resonator 1 and resonator 2 during the sensing process; Δn is the change in environmental refractive index; S1 is the sensitivity of the intrinsic frequency of resonator 1 to the change in environmental refractive index Δn; and s2 is the sensitivity of the intrinsic frequency of resonator 2 to the change in environmental refractive index Δn.

[0150] Formula 5:

[0151] In Equation 5: Q r ω is the radiation quality factor, i.e., the resonant peak Qr value; γ′2 is the energy support frequency in the strongly coupled system; γ′2 is the initial attenuation coefficient of resonator 2 in the zero-decoupling state; m is the conversion coefficient of the difference in intrinsic attenuation coefficient passively generated by the difference in the intrinsic frequency changes of resonators 1 and 2 during the sensing process in the target multi-resonant coupled system, m=5Δn(S1-S2), g n The coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 is the result after correction for the environmental refractive index change Δn, and the correction is g. n = g × Δn(S1 - S2), Ω R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, s2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n This is the non-radiative attenuation coefficient.

[0152] Similarly, by substituting the parameters mentioned above, we obtain the following: Figure 8 and Figure 9 The results are shown. The overall Qr value and absorption intensity change with refractive index and... Figure 6 and Figure 7 Similar. However, the scale of refractive index variation reaches 10. -2 RIU level, closer to Figure 5 The performance in the actual experiment shown demonstrates that the modified Q-switching formula (Equation 5) is more consistent with reality and has a higher confidence level. A schematic diagram of the near-critical coupled Q-switching biosensor physical model based on a strongly coupled system is shown below. Figure 10 As shown: Strongly coupled systems convert the refractive index Δn to Q. r The value changes, and then, combined with the critically coupled system, Q rThe change in value will effectively translate into a significant change in the intensity of the resonant peak, and the frequency will remain essentially constant throughout this process. Simultaneously, the introduction of BIC can effectively optimize the Q-switching sensing effect.

[0153] Example 2

[0154] This embodiment aims to verify Formula 2 of the present invention.

[0155] In asymmetric quasi-BIC systems, the value of the radiation resonance peak Qr can be effectively tuned by changing the coupling between the two resonant cavities. Therefore, placing the quasi-BIC metasurface in such a system... Figure 11 The QSCC sensing performance of a nanoparticle (d) was investigated on a gold substrate (600 nm period, ambient refractive index 1.33 for water, gold nanoparticles with a height of 100 nm). The gold substrate contained a metasurface with two different diameter nanoparticles. a =150nm / d b =130nm, its characterization is as follows Figure 12 As shown, perfect absorption (Q) was achieved on the gold substrate. r =Q n When the overall refractive index of the environment changes, since the critical coupling condition remains unchanged, the resonance only shows a shift in peak wavelength, while the peak intensity remains unchanged. However, when the diameter of the nanoparticles is adjusted to d... a =150nm,d b =100nm, such as Figure 13 The critical coupling condition shown is broken (Q) r Q n The absorption is low, but changing the overall refractive index still results in only a frequency shift. This confirms that the coupling between the two nanoparticles remains unchanged under volume sensing conditions, which is the Q in the quasi-BIC system. r There is no change. In this case, the change in volume refractive index Δn is only related to Δw, and not to Δγ.

[0156] However, as Figure 11 As shown in b, when a SiO2 layer is coated only on NP-a, in Figure 14 and Figure 15 In the meantime, the absorption intensity of the resonance is significantly reduced. This strongly indicates that the intrinsic coupling between the two nanoparticles has changed, thereby altering the Qr value. Due to the large difference in polarizability between NP-a and NP-b, the quasi-BIC system will move away from the BIC, resulting in an increase in the asymmetry factor α. This phenomenon can be explained by the radiation quality factor law of asymmetric BIC metasurfaces, Equation 2: Q r =a+bα -2 Changing the refractive index near only one nanoparticle will cause α to increase (decrease), thus affecting Q. rEffectively reduce (increase). Because the metasurface with a gold film as the substrate forms a one-port system, and because the absorbance of the system is determined by the following...

[0157] Formula 6: When Q r The absorption intensity changes significantly when the value is decreased (increased).

[0158] In addition, such as Figure 11 c in Figure 16 and Figure 17 As shown, by adding a SiO2 layer to NP-b, the polarizability difference between the two nanoparticles first decreases, approaching the BIC point, α is suppressed, and the Qr value increases. Therefore, it begins to enter an overcoupled state, causing a rapid decrease in absorption, and then, after reaching its maximum value, Qr... r The (Qr value) decreases, bringing it closer to the critical coupling state, causing absorption to increase again. Figure 17 In the middle, with Q r The increase (Q) r n As the system moves from an undercoupled state to a critically coupled state, absorption increases.

[0159] Due to the inherent material loss in plasmonic-based asymmetric BIC metasurfaces, to eliminate its influence, we further demonstrated the QSCC mechanism using a dielectric-based BIC metasurface (gold substrate, 600 nm period, ambient refractive index of water 1.33, TiO2 nanoparticles, 100 nm height). Figure 18 In the process, as the overall refractive index changes, the resonant wavelength undergoes a redshift, but the peak absorption changes very little. Q r The slight increase can be attributed to the change in the effective refractive index of the resonant cavity. However, in Figure 19 In the process, when a SiO2 layer is added to NP-a, the refractive index difference between the two nanoparticles increases (α increases), and the system moves from overcoupling to critical coupling, resulting in increased absorption. Figure 20 The situation is exactly the opposite; adding a SiO2 layer on NP-b suppresses α, making Q... r Increases as it moves away from the critical coupling, while absorption decreases.

[0160] This also confirms the effectiveness of the regularity of Formula 2 in this invention.

[0161] Therefore, by selectively modifying the quasi-BIC system and controlling the surface refractive index of two different nanoparticles, the effectiveness of the QSCC sensing mechanism was once again demonstrated.

[0162] Example 3

[0163] ​Based on the aforementioned Embodiments 1 and 2, the effectiveness of the control method was verified, and its good application prospects in the design of optical sensing systems and / or optical sensor devices were also verified. Embodiment 3 further extends the universality of the control method of the present invention to the visible light to short-wave infrared bands in an experimental manner, and demonstrates its better performance than existing metasurface biosensors.

[0164] like Figure 22 As shown, Figure 22 Table a shows the simulated volume sensing performance of a 3D BIC metasurface with lattice periods of 400 nm, 600 nm, and 800 nm. The refractive index of the bulk environment varied between 1.33 and 1.37. This simulation evaluated how different lattice periods affect the sensing performance of the 3D BIC metasurface in response to changes in bulk refractive index. Table b shows the experimental volume and surface sensing performance of the 3D BIC metasurface with lattice periods of 400 nm, 600 nm, and 800 nm. In the experiments, the volume refractive index was varied by adjusting the concentration of the glycerol solution from 0% to 40%. For variations in surface refractive index, atomic layer deposition (ALD) of alumina layers with 5 nm steps was used to simulate the binding of biomolecules. These experimental data provide an in-depth understanding of the practical performance and sensitivity of the 3D BIC metasurface for solid and surface sensing applications.

[0165] First, we experimentally prepared 3D BIC samples with periods of 400, 600, and 800 nm, respectively, to achieve QSCC sensing in the visible (~650 nm), near-infrared (~940 nm), and short-wave infrared (~1260 nm) bands. As shown in the figure below, within the shaded area, whether the overall refractive index is changed by altering the glycerol concentration or the refractive index of the nanostructure surface is changed by depositing an alumina layer via ALD, the resonance peak excited by the QSCC sensing mechanism exhibits very good and significant changes in peak intensity, as well as obvious linewidth broadening.

[0166] Meanwhile, the experimental and simulation results also maintained good consistency.

[0167] This mechanism also has the potential for further application in the infrared band. Our highest Q value can reach 253 (center wavelength 1265nm, linewidth 5nm). For traditional sensing mechanisms, the signal response bandwidth is limited by the resonant peak linewidth. Therefore, under the same conditions, the narrow linewidth of the high Q value resonant peak inevitably leads to a limited signal response bandwidth. However, using the QSCC sensing mechanism, we can achieve a high Q value while obtaining a wider signal response bandwidth due to the adjustable resonant peak linewidth. Therefore, high Q value metasurface sensors can be combined with cheaper and smaller broadband filters to realize more integrated biosensing or imaging systems.

[0168] as follows Figure 23 As shown, Figure 23 In the image, 'a' represents a 3D BIC metasurface sensing module based on the QSCC sensing mechanism, featuring high bandwidth and frequency compatibility, adaptable to various light sources and photoelectric sensors. 'b' shows the surface sensing performance of QSCC in the VIS band. The solid line represents the spectral change with increasing SiO2 layer thickness (0nm SiO2 as background, BG), and the filled pattern curves represent illumination from light sources with bandwidths of 2, 10, and 25 nm, centered at 640 nm. 'c' shows hyperspectral reconstructed images under illumination from light sources with bandwidths of 2, 10, and 25 nm, along with the corresponding line contours on the right. Scale bar: 50 micrometers.

[0169] Based on a three-dimensional BIC metasurface with a lattice period of 400 nm, we have completed an integrated hyperspectral imaging system. Due to the unique properties of the QSCC sensing mechanism, this system further reveals its compatibility with various light sources in a spectrometer-less hyperspectral imaging system. SiO2 strips with thickness gradients of 10–30 nm were fabricated using photolithography. The nanoscale morphology was reconstructed in water under illumination with light sources of different bandwidths. Tunable narrowband illumination (2 nm) at different wavelengths showed different gradient intensity patterns, with correct gradient nanostructure reconstruction at 640 nm. Broadband illumination in the 640 nm band (10 and 25 nm) also effectively reconstructed the gradient morphology, showing significant intensity differentiation, corresponding to SiO2 thicknesses of 10–30 nm. Furthermore, this system achieved a minimum vertical resolution of 3.5 nm and a minimum lateral resolution of 3 μm for SiO2. The highest integrated sensing unit density of this device is 2.7 million (2.7 × 10⁻⁶). 7 The density of superstructure sensors has reached one million units per square centimeter, exceeding the current highest density of one million (1×10⁻⁶) internationally. 7 The level is (units / square centimeter). Furthermore, our system is more integrated, and the sensor chip fabrication is cheaper and more practical, bringing greater potential and application value to the promotion of high-performance biosensors.

Claims

1. A method for controlling the Q value of an optical resonance peak, characterized in that, The method includes: 1) Obtain the inherent property parameters of the target system and the environmental refractive index change value Δn; The target system is a multi-resonant coupling system and / or an asymmetric BIC system; The multi-resonant coupling system has a resonator 1 and a resonator 2. The natural frequency of the resonator 1 redshifts as Δn increases, while the natural frequency of the resonator 2 does not change with Δn. In the zero decoupling state, the frequencies of the resonator 1 and the resonator 2 are equal. The inherent loss of the resonator 1 does not change with Δn, while the inherent loss of the resonator 2 increases as Δn increases. The asymmetric BIC system comprises two nanoparticle metasurfaces with different diameters, heights, materials, or spatial displacements. 2) Construct the associated Qr value based on the environmental refractive index change value Δn obtained in step 1) and the obtained intrinsic property parameters; When the target system is a multi-resonant coupled system, the acquired intrinsic property parameters include: the energy support frequency ω of the coupled system, and the initial attenuation coefficient γ2 of the resonator 2 in the zero-decoupling state. ’ The coupling strength g between resonator 1 and resonator 2, and the Rabi splitting Ω R The sensitivity S1 of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn; the sensitivity S2 of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn; the natural frequency ω1 of harmonic oscillator 1; the natural frequency ω2 of harmonic oscillator 2; and the nonradiative attenuation coefficient γ. n ; The relationship between the resonance peak Qr value and the change in environmental refractive index Δn is expressed as Equation 1 below: Formula 1: ; In the formula: Q r The radiation quality factor, i.e., the resonance peak Q. r Value, ω is the energy support frequency in a strongly coupled system, γ2 ’ Ω represents the initial attenuation coefficient of resonator 2 in the zero-decoupling state, and g represents the coupling strength between resonator 1 and resonator 2. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n The non-radiative attenuation coefficient; When the target system is an asymmetric BIC system, the acquired intrinsic property parameters include: asymmetry factor α; According to the following formula, Equation 2, the radiation quality factor of the asymmetric BIC system: Formula 2: ; In the formula: Q r α is the radiation quality factor, i.e., the resonance peak Qr value; α is the asymmetry factor; and both a and b are characterized by at least two points of data Q. r Substituting α into the calculation results; 3) Based on Equations 1 and 2 from step 2) above: When the target system is a multi-resonant coupled system, the inherent property parameters are substituted into Equation 1 for calculation, and the environmental refractive index change value Δn is adjusted by the calculation result of Qr value and the adjustment purpose to achieve the control of Qr value; The method of adjusting the environmental refractive index change value Δn includes adjusting and / or replacing the liquid system or atmospheric environment in which the target multi-resonance coupling system is located; When the target system is an asymmetric BIC system, the nanoparticles of the asymmetric BIC system are selectively modified according to the adjustment purpose to change the asymmetry factor α in order to control the Qr value. When the target system simultaneously possesses the characteristics of a multi-resonant coupling system and an asymmetric BIC system, at least one of the above methods is used to change the environmental refractive index change value Δn and / or the asymmetry factor α in order to control the Qr value. When the target system is an asymmetric BIC system or contains asymmetric BIC system characteristics, the control requirements are determined according to the resonant peak absorbance expression of Equation 6, and the Qr value is controlled by Equation 2. Formula 6: ; In the formula: Abs is the absorbance, x is the maximum absorbance of the system and is calculated by substituting 1, Q r Q is the radiation quality factor. n ω is the nonradiative quality factor, and ω is the frequency of any harmonic oscillator in the zero-decoupling state. r This is the natural oscillation frequency of the system when there are no losses. This process is performed when the target system contains asymmetric nanostructures NP-a and NP-b. The nanostructures NP-a and NP-b have different structural widths and / or structural radii and / or structural heights and / or spatial relative positions, wherein the structural width and / or structural radius and / or structural height of nanostructure NP-a is greater than the structural width and / or structural radius and / or structural height of nanostructure NP-b. The selective modification process involves modifying the surface of nanostructures NP-a and / or NP-b to create localized refractive index changes.

2. The method for controlling the Q value of an optical resonance peak according to claim 1, characterized in that, Step 2) The relationship between the resonant peak Qr value and the change in environmental refractive index Δn is constructed by combining the critical coupling mechanism with Equation 1, Equation 3 (the coupling strength modification formula between resonator 1 and resonator 2) and Equation 4 (the conversion coefficient calculation formula). Formula 3: ; In Equation 3: g n S1 is the result of the coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 after correction by the environmental refractive index change value Δn, where Δn is the environmental refractive index change value, S1 is the sensitivity of the intrinsic frequency of harmonic oscillator 1 to the environmental refractive index change value Δn, and S2 is the sensitivity of the intrinsic frequency of harmonic oscillator 2 to the environmental refractive index change value Δn. Formula 4: ; In the formula: m is the conversion coefficient of the intrinsic attenuation coefficient difference passively generated by the introduction of the difference in intrinsic frequency changes of resonator 1 and resonator 2 during the sensing process in the target multi-resonant coupling system; Δn is the change in ambient refractive index; S1 is the sensitivity of the intrinsic frequency of resonator 1 to the change in ambient refractive index Δn; and S2 is the sensitivity of the intrinsic frequency of resonator 2 to the change in ambient refractive index Δn.

3. The method for controlling the Q value of an optical resonance peak according to claim 1, characterized in that, After combining Equation 1 with Equations 3 and 4 and making corrections, we obtain Equation 5: Formula 5: ; In the formula: Q r ω is the radiation quality factor, i.e., the resonant peak Qr value, ω is the energy support frequency of the strongly coupled system, and γ2 is the radiation quality factor. ’ Let g be the initial attenuation coefficient of resonator 2 in the zero-decoupling state, m be the conversion coefficient of the difference in intrinsic attenuation coefficient passively generated by the difference in the intrinsic frequency changes of resonator 1 and resonator 2 during the sensing process in the target multi-resonant coupled system, and g be the conversion coefficient of the difference in intrinsic attenuation coefficient changes passively generated by the difference in the intrinsic frequency changes of resonator 1 and resonator 2 during the sensing process. n The coupling strength g between harmonic oscillator 1 and harmonic oscillator 2 is the result after correction for the environmental refractive index change Δn, Ω. R For Rabi splitting, Δn is the change in ambient refractive index, S1 is the sensitivity of the eigenfrequency of harmonic oscillator 1 to the change in ambient refractive index Δn, S2 is the sensitivity of the eigenfrequency of harmonic oscillator 2 to the change in ambient refractive index Δn, and i is a purely imaginary number and is defined as i 2 =-1, ω1 is the natural frequency of harmonic oscillator 1, ω2 is the natural frequency of harmonic oscillator 2, γ n This is the non-radiative attenuation coefficient.

4. The method for controlling the Q value of an optical resonance peak according to claim 1, characterized in that, The local refractive index change and radiation quality factor Q resulting from the surface modification of the nanostructure NP-a are related. r Negative correlation; The local refractive index change and radiation quality factor Q resulting from the NP-b surface modification of the nanostructure are related. r They are positively correlated.

5. An application of the method as claimed in any one of claims 1 to 4, characterized in that, The method is used for modulation and / or design and / or modification of optical sensing systems and / or optical sensor devices.

6. An application according to claim 5, characterized in that, The optical sensing system and / or optical sensor includes a biosensing system and / or biosensor.

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