A high-throughput integrated optical sensor based on a double-layer concave grating structure

Abstract

The present invention discloses a high-throughput integrated optical sensor based on a double-layer concave grating structure. The sensor comprises two composite grating layers and an intermediate layer, with the two composite grating layers positioned above and below the intermediate layer, respectively. The composite grating layer has a concave grating structure comprising several periodic units, each of which includes several periodically or aperiodically arranged micro-nano gratings. The micro-nano gratings are etched with grooves at one end away from the intermediate layer. The grating cross-section of the micro-nano gratings is concave, with an air gap between adjacent micro-nano gratings. This invention, based on the current state of optical sensor research and the advantages of resonant waveguide gratings, features a simple structure and easy fabrication. By designing a concave grating structure, the sensor achieves control of different modes.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano optical devices, and in particular to a high-throughput integrated optical sensor based on a double-layer concave grating structure. Background Art

[0002] Subwavelength micro-nano grating structures are a typical micro-nano photonic structure that has been widely used in optical biosensing and antibody-antigen detection in recent years. Compared to other types of sensors, optical sensors offer advantages such as corrosion resistance, immunity to electromagnetic interference, and low cost, making them widely used in environmental monitoring, chemical analysis, biosensing, and other fields. Because traditional detection devices rely on chemical detection and have low detection efficiency, the integration of advances in micro-nano photonics with integrated optical components has led to the design of micro-nano grating sensors, which can instantly detect information through spectral information, effectively improving sensor performance and increasing sensor accuracy.

[0003] Common optical sensor structures include micro-nano optical fibers, surface plasmons, resonant waveguide gratings, etc. Compared with other structures, resonant waveguide gratings have advantages in optical sensing, such as easy optical coupling, easy on-chip integration, and no need for fluorescent labeling. However, traditional micro-nano grating structures have fewer adjustable structural parameters, making it difficult to achieve optical biosensing with high quality factor (Q) and high sensitivity (S). In recent years, researchers have turned their attention to the research of sensors based on composite grating structures. However, ordinary composite gratings are subject to the mutual constraints of Q and S. From a physical mechanism point of view, to achieve a high-sensitivity grating sensor, more light fields in the grating need to leak into the low-refractive-index material to be tested; at the same time, to obtain a high-quality factor grating sensor, it is necessary to improve the grating's ability to bind the leakage mode light field. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-throughput integrated optical sensor based on a double-layer concave grating structure. Based on the current research status of optical sensors and the advantages of resonant waveguide gratings, the sensor has a simple structure and is easy to prepare. By designing a concave grating structure, it can achieve regulation of different modes.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A high-throughput integrated optical sensor based on a double-layer concave grating structure comprises: two composite grating layers and an intermediate interlayer, wherein the two composite grating layers are located above and below the intermediate interlayer, respectively; the composite grating layer is a concave grating structure comprising a plurality of periodic units, each periodic unit comprising a plurality of periodically or non-periodically arranged micro-nano gratings; a groove is etched at one end of the micro-nano grating away from the intermediate interlayer; the grating cross section of the micro-nano grating is concave, and an air gap is provided between two adjacent micro-nano gratings.

[0007] Furthermore, the composite grating layer is made of a high refractive index material such as Si, GaAs or SiN.

[0008] Furthermore, the intermediate layer is made of a low-refractive material such as BCB, SU-8 or SiO2.

[0009] Furthermore, the micro-nano grating changes the grating cross section into a rectangle by controlling the depth of the etched grooves.

[0010] Furthermore, two composite grating layers are symmetrically arranged above and below the intermediate layer.

[0011] Furthermore, the integrated optical sensor regulates the leakage mode resonance mode of the grating by changing the spacing between two adjacent micro-nano gratings, regulates the FP cavity mode of the grating by changing the thickness of the intermediate layer, and changes the shape of the grating cross section by changing the etching depth of the groove.

[0012] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: The high-throughput integrated optical sensor based on a double-layer concave grating structure provided by the present invention is mainly composed of a double-layer composite grating layer and an intermediate interlayer. The sensor exhibits a double resonance peak phenomenon when used for gas sensing. It has a simple structure and is easy to process. The leaky mode resonance mode of the grating can be controlled by varying the spacing between the micro-nano gratings; the FP cavity mode of the grating can be controlled by varying the thickness of the intermediate interlayer; and the shape of the grating cross section can be controlled by varying the etching depth of the grating grooves, thereby achieving control of the quality factor and sensitivity. The sensor is composed of all-dielectric materials, is lossless, and has high sensitivity while also achieving a high quality factor. It has great application prospects in nanoscale sensing in the field of micro-nano optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 Schematic diagram of the structure of a high-throughput integrated optical sensor based on a double-layer concave grating structure according to embodiment 1 of the present invention;

[0015] Figure 2 This is a schematic structural diagram of a high-throughput integrated optical sensor based on a double-layer concave grating structure according to a second embodiment of the present invention;

[0016] Figure 3This is a spectrum diagram of two resonance peaks of the optical sensor of Example 2 of the present invention when the etching depth of the groove is changed;

[0017] Figure 4 The reflection spectrum of the two resonance peaks of the optical sensor of the second embodiment of the present invention when the refractive index of the substance to be measured changes;

[0018] Figure 5 This is the evolving reflectance spectrum of the single and double resonance peaks of the optical sensor of the second embodiment of the present invention when the spacing of the composite grating changes;

[0019] Explanation of the accompanying symbols: 1. Intermediate layer; 2. Upper composite grating layer; 3. Lower composite grating layer; 4. Periodic unit; 5. Micro-nano grating. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] The purpose of the present invention is to provide a high-throughput integrated optical sensor based on a double-layer concave grating structure. Based on the current research status of optical sensors and the advantages of resonant waveguide gratings, the sensor has a simple structure and is easy to prepare. By designing a concave grating structure, it can achieve regulation of different modes.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1 He Ru Figure 2 As shown, an embodiment of the present invention provides a high-throughput integrated optical sensor based on a double-layer concave grating structure, comprising: two composite grating layers and an intermediate interlayer 1, wherein the two composite grating layers include an upper composite grating layer 2 and a lower composite grating layer 3, which are respectively located above and below the intermediate interlayer 1. The composite grating layer is a concave grating structure, comprising a plurality of periodic units 4, each periodic unit 4 including a plurality of periodically or non-periodically arranged micro-nano gratings 5, wherein grooves are etched at one end of the micro-nano grating 5 away from the intermediate interlayer 1, and the grating cross section of the micro-nano grating 5 is concave, with an air gap between two adjacent micro-nano gratings. The leaky mode resonant mode of the grating is controlled by changing the spacing between the two adjacent micro-nano gratings 5, the FP cavity mode of the grating is controlled by changing the thickness of the intermediate interlayer 1, and the shape of the grating cross section is changed by changing the etching depth of the groove.

[0024] The composite grating layer is made of a high refractive index material such as Si (silicon), GaAs (gallium arsenide) or SiN (silicon nitride).

[0025] The intermediate layer is made of a low-refractive material, such as BCB (benzocyclobutene), SU-8 (a photoresist) or SiO2 (silicon dioxide).

[0026] The micro-nano grating 5 changes the grating cross section into a rectangle by controlling the depth of the etched grooves.

[0027] The upper and lower composite grating layers can be symmetrical or asymmetrical about the intermediate layer. In the embodiment of the present invention, the two composite grating layers are symmetrically arranged on the upper and lower surfaces of the intermediate layer 1. The integrated optical sensor achieves refractive index sensing of liquids or gases by changing the refractive index of the detected substance. By detecting the wavelength shift of the resonance peak caused by changes in the surface thickness of the composite grating layer, immune recognition of biomolecules in the liquid is achieved.

[0028] In the embodiment of the present invention, the intermediate layer 1 is made of BCB with a refractive index of 1.54, and the micro-nano grating 5 is made of silicon (Si) with a refractive index of 3.47. The thickness h of the intermediate layer 1 is 1000 nm.

[0029] like Figure 1 As shown, in the first embodiment of the present invention, the periodic unit includes three micro-nano gratings, the height of the three micro-nano gratings is L, and the widths of the three micro-nano gratings are w1, w2, and w3 respectively; the spacing between two adjacent micro-nano gratings in the three micro-nano gratings is d1 and d2 respectively; the groove depths of the three micro-nano gratings are g1, g2, and g3, the groove widths are x1, x2, and x3, and the thickness of the intermediate layer is h.

[0030] like Figure 2 As shown, in the second embodiment of the present invention, the periodic unit includes two micro-nano gratings, the height of the micro-nano grating is L=200nm, the widths of the two micro-nano gratings are w1=w2=200nm respectively, the groove depths of the two micro-nano gratings are g1=g2, and the groove widths are x1=x2; the distance d between two adjacent micro-nano gratings is 205nm~350nm, that is, one period includes two rectangular micro-nano grating structures, the micro-nano gratings are periodically arranged in the xz plane, the periodic unit is 800nm, it is infinitely long in the y direction, and the TM wave is vertically incident.

[0031] For Example 2, Figure 3The integrated optical sensor's reflectance spectra are plotted at different groove etch depths, with the distance between two identical micro-nano gratings 5 ​​within a period being 250 nm. When the etch depth g = 0, the grating has a rectangular cross-section, with two identical rectangular gratings within a period. When the etch depth g is equal to the height L of the concave grating, four rectangular gratings are contained within a period. As the etch depth increases, the device's quality factor improves.

[0032] For Example 2, Figure 4 The optical sensor demonstrates the reflection spectra of two resonance peaks under different refractive index environments when the groove etch depth g = 0. The distance between the composite gratings is selected to be d = 205 nm, corresponding to refractive indices of 1, 1.02, 1.04, 1.06, 1.08, and 1.1 for the detected substances, respectively. Changes in the ambient refractive index cause the center wavelength of the sensor's output spectrum to shift, thus enabling optical refractive index sensing. The calculated sensitivity of the first resonance peak is 413 nm / RIU with a quality factor of 20113; the sensitivity of the second resonance peak is 237 nm / RIU with a quality factor of 46550.

[0033] For Example 2, Figure 5 The evolution of the single and double peaks of the optical sensor when the composite grating spacing changes is shown when the groove etching depth g=0. Figure 5 It can be seen that as the spacing of the composite grating increases, the two resonance peaks (non-degenerate state) gradually evolve into one resonance peak (degenerate state). Therefore, the evolution of the single and double resonance peaks of the device can be controlled by changing the spacing of the composite grating. When evolving from the non-degenerate state to the degenerate state, the sensing performance of the device decreases.

[0034] pass Figure 4 and Figure 5 Analysis, combined with Figure 3 From the spectrum diagram of groove depth, it can be found that the presence of grooves improves the sensing performance of the sensor. The higher the groove depth, the better the sensor performance.

[0035] The high-throughput integrated optical sensor based on a double-layer concave grating structure provided by the present invention is a dual-resonance peak sensor device based on an all-dielectric structure. The output dual resonant peaks can exist independently, with one having high sensitivity and the other having a high quality factor. Traditional grating sensors often suffer from the mutual constraints between S and Q. By rationally designing structural parameters such as the width, spacing, and etching depth of the grating within the periodic unit, as well as the thickness of the low-refractive-index interlayer, the leaky-mode resonant mode and FP cavity mode of the grating are regulated. The resulting BIC state decouples S and Q, enabling the detection of gases, liquids, and other substances with different refractive indices. This has important applications in fields such as chemistry, medicine, and integrated optics.

[0036] In summary, the technical advantages of the high-throughput integrated optical sensor based on the double-layer concave grating structure provided by the present invention are reflected in the following aspects: (1) The optical sensor with the all-dielectric structure is lossless, non-biotoxic, and has a long service life; (2) The structure proposed by the present invention can change the shape of the grating cross section by changing the etching depth of the groove, thereby optimizing the sensing performance; (3) The double resonance peaks appearing in the reflection spectrum have high sensitivity and quality factor, which is convenient for detection and measurement, and can provide two detection points at the same time; (4) The two resonance peaks appearing in the reflection spectrum can flexibly control the evolution of single and double peaks by regulating structural parameters; (5) The optical sensor described in the present invention realizes the refractive index sensing of liquid or gas by changing the refractive index change of the detection substance; by detecting the change in the thickness of the composite grating surface to cause the wavelength drift of the resonance peak, the immune recognition of the biological molecules in the detection substance is realized, and the purpose of realizing multiple detections with one sample is achieved.

[0037] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A high-throughput integrated optical sensor based on a double-layer concave grating structure, characterized in that: include: Two composite grating layers and an intermediate interlayer, the two composite grating layers are respectively located above and below the intermediate interlayer, the composite grating layer is a concave grating structure, including a plurality of periodic units, each periodic unit including a plurality of periodically or non-periodically arranged micro-nano gratings, a groove is etched at one end of the micro-nano grating away from the intermediate interlayer, the grating cross section of the micro-nano grating is concave, and an air gap is provided between two adjacent micro-nano gratings; The integrated optical sensor regulates the leaky mode resonance mode of the grating by changing the spacing between two adjacent micro-nano gratings, regulates the FP cavity mode of the grating by changing the thickness of the intermediate layer, and changes the shape of the grating cross section by changing the etching depth of the groove; The micro-nano grating changes the grating cross section into a rectangle by controlling the depth of the etched grooves.

2. The high-throughput integrated optical sensor based on a double-layer concave grating structure according to claim 1, characterized in that: The composite grating layer is made of high refractive index material, such as Si, GaAs or SiN.

3. The high-throughput integrated optical sensor based on a double-layer concave grating structure according to claim 1, characterized in that: The intermediate layer is made of low-refractive material, such as BCB, SU-8 or SiO2.

4. The high-throughput integrated optical sensor based on a double-layer concave grating structure according to claim 1, characterized in that: The two composite grating layers are symmetrically arranged on the upper and lower sides of the middle interlayer.

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