Imaging sensor based on full stokes polarized superlens

Abstract

The application discloses an imaging sensor based on a full-Stokes polarization superlens, and relates to the field of optical sensing.The imaging sensor comprises a sensing excitation light source, an adjustable attenuator, a polarizer, a coupling prism, a sensing chip, a first objective lens, a full-Stokes polarization superlens, a second objective lens, an imaging lens and a CCD imaging camera; the sensing excitation light source emits monochromatic light as system incident light, which sequentially passes through the adjustable attenuator and the polarizer, and is incident onto the surface of the sensing chip to generate surface plasmon resonance after passing through the coupling prism; reflected light is converged onto the polarization superlens by the first objective lens, and then converged onto the second objective lens; subsequently, the imaging lens is used for imaging to the CCD camera; the property change of a to-be-measured sample leads to surface plasmon resonance of the sensing chip, which causes the analysis information of the full-Stokes polarization superlens to change, and further causes the image obtained by the CCD imaging camera to change.The application can perform single-shot phase imaging on a refractive index sample.

Description

Technical Field

[0001] This application relates to the field of optical sensing, and in particular to an imaging sensor based on a fully Stokes polarization superlens. Background Technology

[0002] With the development of advanced imaging technologies, surface plasmon sensing technology, already possessing excellent sensitivity, has been endowed with entirely new sensing capabilities, evolving into a powerful tool for spatially resolved molecular interaction analysis, particularly in the life sciences and analytical chemistry fields. Modern surface plasmon imaging sensing systems achieve high spatial resolution while also monitoring binding dynamics in real time, and their commercial platforms are now widely used in pharmaceuticals and diagnostics. Traditional implementation methods primarily rely on intensity detection, while alternatives include angle modulation, wavelength interrogation, and phase interrogation. Notably, phase retrieval methods are the most sensitive. However, traditional phase retrieval methods have inherent limitations due to their fundamental working principles. Summary of the Invention

[0003] The purpose of this application is to provide an imaging sensor based on a fully Stokes polarization superlens, which can perform phase sensing by taking a single image of the sample.

[0004] To achieve the above objectives, this application provides the following solution:

[0005] An imaging sensor with a fully Stokes polarization superlens includes: a sensing excitation source, an adjustable attenuator, a polarizer, a coupling prism, a sensing chip, a first objective lens, a fully Stokes polarization superlens, a second objective lens, an imaging lens, and a CCD imaging camera.

[0006] The sensing excitation light source emits monochromatic light as the system incident light, which passes through an adjustable attenuator and a polarizer in sequence. Then, the beam of light with the polarization state determined by the polarizer passes through a coupling prism and is incident on the lower surface of the sensing chip at a fixed excitation angle to generate surface plasmon resonance. The reflected light is converged by the first objective lens onto a fully Stokes polarized superlens, then converged to the second objective lens, and finally imaged onto the CCD camera by the imaging lens.

[0007] The change in the refractive index of the liquid being tested causes a change in the surface plasmon resonance generated by the sensing chip, which in turn causes a change in the polarization information (sensing amplitude / phase) obtained by the full Stokes analysis based on a single exposure, and consequently a change in the image obtained by the CCD imaging camera.

[0008] The imaging sensor of the fully Stokes polarization superlens is characterized in that three sets of nanopillars in the fully Stokes polarization superlens impart six different phase profiles to three sets of orthogonally polarized light to reconstruct the Stokes image. The three sets of orthogonally polarized light include x and y polarization pairs, 45-degree and 135-degree polarization pairs, and left-handed and right-handed circularly polarized pairs. The imparted phase profiles are as follows: :

[0009] ;

[0010] Where k represents the wave number, and f defines the focal length of the superlens. The off-axis focusing position of each polarization component is defined, where a = 1, 2, 3 represents a polarization pair and b = 1, 2 represents a polarization state in that polarization pair.

[0011] The sensing chip's ability to simultaneously sense both amplitude and phase parameters in a single exposure is represented as follows:

[0012] ;

[0013] ;

[0014] Where IR is the sensing amplitude and DP is the sensing phase. , Denotes the Stokes parameters obtained from a fully Stokes polarizing superlens, where

[0015] This represents the intensity value of the x-polarization component in a CCD imaging camera. This represents the intensity value of the y-polarization component in a CCD imaging camera. This represents the intensity value of the 45-degree polarization component in a CCD imaging camera. This represents the intensity value of the 135-degree polarization component in a CCD imaging camera. This represents the intensity value of the left-hand polarization component in a CCD imaging camera. This represents the intensity value of the right-hand polarization component in a CCD imaging camera.

[0016] Optionally, the monochromatic light emitted by the sensing excitation light source is 670nm.

[0017] Optionally, the sensing chip includes a K9 glass incident layer, a gold layer, and a sensing layer arranged sequentially from bottom to top.

[0018] Optionally, the imaging sensor based on the all-Stokes polarization superlens is characterized in that the all-Stokes polarization superlens arranges three sets of nanopillars in an alternating manner.

[0019] Optionally, the imaging sensor based on a fully Stokes polarization superlens is characterized in that the lower surface K9 glass incident layer of the sensing chip is coupled to the coupling prism through a refractive index matching liquid.

[0020] Optionally, the total transmission matrix of the sensing chip is:

[0021] ;

[0022] in, ;

[0023] ;

[0024] in, The total transmission matrix of the sensor chip, Let i be the transmission matrix of the i-th layer of the sensor chip. , These are the four components of the transmission matrix of the i-th layer of the sensor chip. This represents the phase delay of light propagating in the i-th layer of the sensor chip. This represents the effective optical admittance of the i-th layer of the sensor chip. The wave vector in vacuum. This represents the thickness of the i-th layer of the sensor chip. The complex refractive index of the first layer of the sensor chip. Let be the complex refractive index of the i-th layer of the sensor chip. This indicates the angle of incidence of the light beam.

[0025] Optionally, the signal receiving surface of the CCD is perpendicular to the direction of the emitted light.

[0026] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0027] This application discloses an imaging sensor based on a fully Stokes polarization superlens, relating to the field of optical sensing. The imaging sensor includes: a sensing excitation source, an adjustable attenuator, a polarizer, a coupling prism, a sensing chip, a first objective lens, a fully Stokes polarization superlens, a second objective lens, an imaging lens, and a CCD imaging camera. Changes in the refractive index of the liquid under test cause changes in the surface plasmon resonance generated by the sensing chip, subsequently altering the polarization (sensing amplitude / sensing phase) superlens information obtained from full Stokes analysis using a single-shot imaging technique, thereby changing the image obtained by the CCD imaging camera. This application enables snapshot phase imaging of refractive index samples using a single-shot fully Stokes polarization superlens, avoiding complex interference phase reconstruction optical paths and achieving high-sensitivity phase sensing using a single optical path. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of the optical module of an imaging sensor based on a fully Stokes polarization superlens provided in an embodiment of this application.

[0030] Figure 2 This is a schematic diagram of the structure of a fully Stokes polarization superlens and a schematic diagram of a Stokes image.

[0031] Figure 3 This is a schematic diagram of refractive index-resonance angle spectrum, based on a single full Stokes sensor image with a given mass fraction and phase sensing reconstruction of the refractive index.

[0032] Figure 4 The images include gradient thin film samples and their full Stokes sensing images (including amplitude and phase images), gradient phase curves, and three-dimensional reconstructions.

[0033] Figure 5 A physical image of the surface plasmon sensor prepared for the embodiments of this application (left image) and a scanning electron microscope (SEM) characterization image of the all-Stokes polarization superlens (right image). Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In the 21st century, the field of life and health has seen widespread attention for biosensors in numerous areas, including biosensing, chemical analysis, medical diagnostics, food safety, and pharmaceuticals. Among these, surface plasmon resonance imaging (SPRi), a label-free biosensing technique, plays a crucial role in real-time monitoring of molecular interactions due to its superior refractive index (RI) sensitivity. Metal surfaces possess a large number of free electrons. Under certain coupling conditions, collective coupled oscillations of these free electrons can be excited at the metal-dielectric interface, a phenomenon known as surface plasmon resonance (SPR). Normally, direct incident light onto a metal surface cannot excite plasmonic waves; a coupling prism is needed to amplify the wave vector of the incident light to excite the SPR effect. Since the excited SPR effect is highly sensitive to changes in the dielectric constant of metal surface samples, this characteristic can be used to detect the refractive index of the sample with high sensitivity. Phase sensing in SPR (Spectroradiometer) is typically the most sensitive. To detect the minute phase shift induced by SPR, traditional methods rely on complex interferometry techniques (such as Mach-Zehnder or Michelson interferometers), requiring precise optical path alignment and path matching. Metasurfaces (two-dimensional subwavelength structures) offer a feasible solution to these challenges. Compared to traditional optical elements, metasurfaces offer significant advantages such as ultrathinness, negligible weight, and high-dimensional manipulation. They enable flexible manipulation of multiple polarization channels without the need for interferometric design, achieving comprehensive optical field analysis and quantitative phase extraction.

[0036] This invention aims to address the core requirement of interference-free, robust phase sensing by utilizing non-destructive dielectric metasurfaces. It proposes a paradigm-shifting robust sensing microscopy platform that seamlessly integrates a metasurface-enabled, fully Stokes imaging polarimeter with an SPR sensor. By leveraging the wavefront engineering capabilities of metasurfaces, this invention enables the direct, single-exposure, interference-free acquisition of the complete Stokes parameter set on the SPR sensor surface. This achieves simultaneous, high-sensitivity quantization of intensity modulation and phase shifts caused by SPR enhancement interactions, and delivers significant advantages such as rapid real-time monitoring, robust resistance to environmental disturbances, and broadband operation.

[0037] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] In one exemplary embodiment, such as Figure 1As shown, an imaging sensor with a fully Stokes polarization superlens is provided, including: a sensing excitation light source 1, an adjustable attenuator 2, a polarizer 3, a coupling prism 4, a sensing chip 5, a first objective lens 6, a fully Stokes polarization superlens 7, a second objective lens 8, an imaging lens 9, and a CCD imaging camera 10.

[0039] The sensing excitation light source 1 emits monochromatic light as the system incident light, which passes through the adjustable attenuator 2 and the polarizer 3 in sequence. Then, the beam of light with the polarization state determined by the polarizer 3 passes through the coupling prism 4 and is incident on the lower surface of the sensing chip 5 at a fixed excitation angle to generate surface plasmon resonance. The reflected light is converged by the first objective lens 6 onto the all-Stokes polarization superlens 7, and then converged onto the second objective lens 8. Subsequently, it passes through the imaging lens 9 to the CCD imaging camera 10.

[0040] The change in the refractive index of the liquid being tested causes a change in the surface plasmon resonance generated by the sensing chip 5, which in turn causes a change in the information of the all-Stokes polarization superlens 7 based on single-shot imaging technology, and consequently causes a change in the image obtained by the CCD imaging camera 10.

[0041] like Figure 2 As shown, the three sets of nanopillars in the all-Stokes polarization superlens assign six different phase profiles to three sets of orthogonally polarized light to reconstruct the Stokes image. These three sets of orthogonally polarized light include x and y polarization pairs, 45-degree and 135-degree polarization pairs, and left-handed and right-handed circular polarization pairs. According to the Stokes image sensing chip, the simultaneous sensing of amplitude and phase dual parameters in a single exposure is expressed as follows:

[0042] ;

[0043]

[0044] In one specific embodiment, the monochromatic light emitted by the sensing excitation light source 1 is 670nm.

[0045] In one specific embodiment, the incident light of the system generates an evanescent wave through the total internal reflection structure provided by the coupling prism 4, which is used to excite the sensor chip 5, which is composed of a 50nm gold thin film, to generate surface plasmon resonance.

[0046] In one specific embodiment, the lower surface of the sensing chip 5 is coupled to the coupling prism 4 via a refractive index matching liquid.

[0047] In one specific embodiment, the signal receiving surface of the CCD imaging camera 10 is perpendicular to the direction of the emitted light.

[0048] In a specific embodiment, the transmission of the multilayer sensing chip can be represented as:

[0049] ;

[0050] in, Let i be the transmission matrix of the i-th layer of the sensor chip. These are the four components of the transmission matrix of the i-th layer of the sensor chip. This represents the phase delay of light propagating in the i-th layer of the sensor chip. This represents the effective optical admittance of the i-th layer of the sensor chip. The wave vector in vacuum. This represents the thickness of the i-th layer of the sensor chip. The complex refractive index of the first layer of the sensor chip. Let be the complex refractive index of the i-th layer of the sensor chip. Indicates the angle of incidence of the light beam;

[0051] ;

[0052] The total transmission matrix of the sensor chip, These represent the different components of the total transmission matrix. The complex reflection coefficients are:

[0053] ;

[0054] in This represents the total reflectance of a multilayer sensor chip.

[0055] Using the transfer matrix method (TMM) described above, the following can be calculated: Figure 3 The refractive index-angle spectrum is shown. By incident at the resonance angle, NaCl solutions with different mass fractions (c%) can be subjected to full Stokes single-shot imaging sensing. It can be seen that when the refractive index change is 0.0005, the sensing phase change of the proposed invention is 15 degrees, at which point the sensitivity reaches 30,000 degrees / unit refractive index, which is much higher than that of the spectral / angle SPR refractive index sensing.

[0056] Figure 4 As shown, this application introduces a gradient thickness structure for verifying thickness sensing of surface plasmon resonance. A silicon dioxide thin film with a gradient thickness was fabricated on sensor chip 5. Thickness sensing of the gradient film was performed using the proposed system, and amplitude and phase images of the gradient film were obtained. The images show a sensing phase of 32 deg over a lateral dimension of 440 μm. Based on the SPR phase response calculated using the TMM model, the thickness values ​​corresponding to different positions can be reconstructed. For a sample variation of 9 nm in this model, the proposed method exhibits a thickness sensitivity of up to 0.28 deg / nm for thickness reconstruction.

[0057] like Figure 5 As shown, in order to verify the feasibility and authenticity of the imaging sensor based on the all-Stokes polarization superlens proposed in this application, the inventors prepared an experimental prototype. Figure 5 The left side shows the actual packaged surface plasmon resonance sensor, where you can see the sensing chip and the liquid sample to be tested introduced through a conduit. Figure 5 The right side shows a partial scanning electron microscope (SEM) image of the all-Stokes polarization superlens. The SEM image clearly shows that the superlens is composed of a large number of nanopillars arranged in a specific staggered pattern, and its structural parameters are similar to... Figure 2 The design conforms to the formula, verifying that micro-nano fabrication processes can precisely prepare metasurface structures for decoupling polarization information. Practical testing results demonstrate that the sensor can effectively perform multi-dimensional light field detection under a single exposure.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An imaging sensor based on a full stokes polarized superlens, characterized in that, include: The sensor excitation source, adjustable attenuator, polarizer, coupling prism, sensor chip, first objective lens, all-Stokes polarization superlens, second objective lens, imaging lens and CCD imaging camera. The sensing excitation light source emits monochromatic light as the system incident light, which passes through the adjustable attenuator and the polarizer in sequence. Then, it passes through the coupling prism with the polarization state determined by the polarizer. The reflected light is then converged by the first objective lens onto the all-Stokes polarization superlens, and then converged to the second objective lens. Finally, it is imaged onto the CCD camera by the imaging lens. The lower surface of the sensing chip is coupled to the coupling prism via a refractive index matching liquid. Changes in the refractive index of the sensing liquid cause changes in the surface plasmon resonance generated by the sensing chip, subsequently altering the polarization information obtained from a single-exposure full Stokes analysis. This polarization information includes sensing amplitude and sensing phase, which in turn changes the image obtained by the CCD imaging camera. The three sets of nanopillars in the full Stokes polarization superlens assign different six phase profiles to three sets of orthogonally polarized light to reconstruct the Stokes image. These three sets of orthogonally polarized light include x and y polarization pairs, 45-degree and 135-degree polarization pairs, and left-handed and right-handed circular polarization pairs. The assigned phase profiles are... : ； Where k represents the wave number, and f defines the focal length of the superlens. The off-axis focusing position of each polarization component is defined, where a = 1, 2, 3 represents a polarization pair, and b = 1, 2 represents a polarization state in that polarization pair; The sensor chip's ability to simultaneously sense both amplitude and phase parameters in a single exposure is represented as follows: ； ； Where IR is the sensing amplitude and DP is the sensing phase. , Denotes the Stokes parameters obtained from a fully Stokes polarizing superlens, where This represents the intensity value of the x-polarization component in a CCD imaging camera. This represents the intensity value of the y-polarization component in a CCD imaging camera. This represents the intensity value of the 45-degree polarization component in a CCD imaging camera. This represents the intensity value of the 135-degree polarization component in a CCD imaging camera. This represents the intensity value of the left-hand polarization component in a CCD imaging camera. This represents the intensity value of the right-hand polarization component in a CCD imaging camera.

2. The imaging sensor based on a fully Stokes polarization superlens according to claim 1, characterized in that, The monochromatic light emitted by the sensor excitation source is 670nm.

3. The imaging sensor based on a fully Stokes polarization superlens according to claim 1, characterized in that, The sensing chip includes a K9 glass incident layer, a gold layer, and a sensing layer arranged sequentially from bottom to top.

4. The imaging sensor based on a fully Stokes polarizing superlens according to claim 1, characterized in that, The fully Stokes polarizing superlens arranges three sets of nanopillars in an alternating manner.

5. The imaging sensor based on a fully Stokes polarization superlens according to claim 1, characterized in that, The overall transmission matrix of the sensor chip is: ； ； ； in, The total transmission matrix of the sensor chip, Let i be the transmission matrix of the i-th layer of the sensor chip. These are the four components of the transmission matrix of the i-th layer of the sensor chip. This represents the phase delay of light propagating in the i-th layer of the sensor chip. This represents the effective optical admittance of the i-th layer of the sensor chip. The wave vector in vacuum. This represents the thickness of the i-th layer of the sensor chip. The complex refractive index of the first layer of the sensor chip. Let be the complex refractive index of the i-th layer of the sensor chip. This indicates the angle of incidence of the light beam.

6. The imaging sensor based on a fully Stokes polarization superlens according to claim 1, characterized in that, The signal receiving surface of the CCD is perpendicular to the direction of the emitted light.

Images