Circular polariscope and spectral analysis method thereof

Abstract

The application discloses a circularly polarized spectrometer and a spectral analysis method thereof, and relates to the technical field of circularly polarized spectrum analysis. The chiral structure layer of the circularly polarized photodetector of the circularly polarized spectrometer comprises a left-handed chiral structure array and a right-handed chiral structure array which are independent and mirror-symmetric; the photosensitive layer comprises a first photosensitive unit and a second photosensitive unit; the first photosensitive unit is electrically connected with a first signal detection module through a first electrode group; the second photosensitive unit is electrically connected with a second signal detection module through a second electrode group; the circularly polarized photodetector is used for collecting left-handed response current and right-handed response current signals under monochromatic light of the same wavelength; and the circularly polarized spectrometer is used for calculating left-handed circularly polarized light intensity and right-handed circularly polarized light intensity according to a formula. The circularly polarized spectrometer can synchronously and quantitatively separate left-handed and right-handed circularly polarized light intensity at a monochromatic wavelength point, and has high device stability and process compatibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circularly polarized spectrum analysis, in particular to a circularly polarized spectrometer and a spectrum analysis method thereof. BACKGROUND

[0002] Circularly polarized luminescence (CPL) refers to a physical phenomenon that the intensity of left-handed circularly polarized light is different from that of right-handed circularly polarized light emitted by a chiral luminescent system during radiative recombination. The circularly polarized luminescence spectrum can not only reflect the chiral information of the electronic excited state of a material, but also has important application value in the fields of optical communication, biomedical imaging, material analysis and quantum computing, and therefore it is of great significance to accurately and quantitatively analyze the spectrum of circularly polarized light.

[0003] In the existing circularly polarized spectrum detection technology, a traditional circularly polarized spectrometer usually adopts a bulk optical scheme of combining a quarter-wave plate with a polarizer, and detects the circularly polarized light after converting it into linearly polarized light. Such a system has a complex structure, a large volume, and a high requirement for light path stability, which is not conducive to system miniaturization and on-chip integration, and it is difficult to simultaneously obtain the spectral intensity distribution of left-handed circularly polarized light and right-handed circularly polarized light under the same time condition. In order to realize the miniaturization of the circularly polarized spectrometer, an integrated scheme combining a photodetector and a signal processing algorithm is proposed, and the technical route mainly includes a circularly polarized light detector based on chiral hybrid perovskite materials, a circularly polarized light detector based on chiral organic materials, and a circularly polarized light detector based on chiral metal nanostructures.

[0004] However, the above-mentioned schemes have certain limitations: the chiral hybrid perovskite and chiral organic material devices have poor stability and are easily affected by environmental factors; and the detector based on chiral metal structure usually requires a complex nano-processing technology, and has insufficient compatibility with standard silicon-based semiconductor processes, which restricts its application in large-scale manufacturing and system integration. In addition, the existing technology usually adopts a sequential switching of polarization states or a single detection channel for measurement, which makes it difficult to simultaneously obtain the response signals of left-handed circularly polarized light and right-handed circularly polarized light under the same wavelength and same time condition, and the left-handed and right-handed signals are easily interfered with each other, resulting in limited accuracy and stability of light intensity quantitative analysis. SUMMARY

[0005] One object of the first aspect of the present application is to provide a circularly polarized spectrometer based on a full-silicon-based circularly polarized photodetector, which solves the technical problems in the prior art that the circularly polarized spectrum detection technology is difficult to simultaneously and quantitatively separate the left-handed and right-handed circularly polarized light intensities at a monochromatic wavelength point, and generally has insufficient device stability and poor process compatibility.

[0006] Another object of the first aspect of the present application is to further improve the responsivity and selective distinguishing ability of the circularly polarized light photodetector to left-handed circularly polarized light and right-handed circularly polarized light.

[0007] An object of the second aspect of the present application is to provide a spectral analysis method based on the circularly polarized light spectrometer.

[0008] To achieve the object of the first aspect of the present application, the present application provides a circularly polarized light spectrometer based on a full-silicon circularly polarized light photodetector, wherein the circularly polarized light photodetector of the circularly polarized light spectrometer comprises a photosensitive layer, a dielectric layer and a chiral structure layer arranged in a stack from bottom to top, the chiral structure layer comprises a left-handed chiral structure array and a right-handed chiral structure array which are independent and mirror-symmetric, the photosensitive layer comprises a first photosensitive unit corresponding to the left-handed chiral structure array and a second photosensitive unit corresponding to the right-handed chiral structure array, the first photosensitive unit is electrically connected to a first signal detection module through a first electrode group, the second photosensitive unit is electrically connected to a second signal detection module through a second electrode group, a left-handed response current is output through the first signal detection module, and a right-handed response current signal is output through the second signal detection module, and the materials of the photosensitive layer and the chiral structure layer are silicon, and the material of the dielectric layer is silicon dioxide.

[0009] The circularly polarized light photodetector is used to collect the left-handed response current and the right-handed response current signal under monochromatic light of the same wavelength.

[0010] The circularly polarized light spectrometer calculates the left-handed circularly polarized light intensity and the right-handed circularly polarized light intensity according to the following formula:

[0011] ;

[0012] wherein, is the responsivity of the left-handed chiral structure array to left-handed circularly polarized light, is the responsivity of the left-handed chiral structure array to right-handed circularly polarized light, is the responsivity of the right-handed chiral structure array to left-handed circularly polarized light, is the responsivity of the right-handed chiral structure array to right-handed circularly polarized light, is the left-handed circularly polarized light intensity, is the right-handed circularly polarized light intensity, is the left-handed response current, is the right-handed response current.

[0013] Optionally, the left-handed chiral structure array comprises a plurality of left-handed chiral units arranged along a first horizontal direction, each of the left-handed chiral units comprises a plurality of left-handed chiral structures connected head to tail along a second horizontal direction, each of the left-handed chiral structures comprises a vertical portion extending along the second horizontal direction and a first bending portion and a second bending portion respectively protruding on both sides of the vertical portion and being chiral symmetric, the first bending portion has two first arc-shaped edges connected to the side edges of the vertical portion and parallel to each other, the two first arc-shaped edges are spaced apart by a first preset distance, the second bending portion has two second arc-shaped edges connected to the side edges of the vertical portion and parallel to each other, the two second arc-shaped edges are spaced apart by a first preset distance, the first arc-shaped edge and the second arc-shaped edge are opposite in direction and have a first preset angle.

[0014] Optionally, the radius of curvature of the first arc-shaped edge and the second arc-shaped edge is any value in a range from 100 nm to 115 nm, and the first preset angle is any value in a range from 50° to 55°.

[0015] Optionally, the vertical portion comprises a first end and a second end, the first arc-shaped edge is arranged to bend towards the first end, and the second arc-shaped edge is arranged to bend towards the second end, wherein the first end is spaced apart from the second arc-shaped edge by a third preset distance, and the second end is spaced apart from the other second arc-shaped edge by a fourth preset distance.

[0016] Optionally, the first preset distance is any value in a range from 110 nm to 130 nm, the third preset distance is any value in a range from 60 nm to 75 nm, and the fourth preset distance is any value in a range from 110 nm to 140 nm.

[0017] Optionally, the thickness of the left-handed chiral structure is any value in a range from 110 nm to 130 nm.

[0018] Optionally, the thickness of the medium layer is any value in a range from 580 nm to 620 nm, and the thickness of the photosensitive layer is any value in a range from 1.1 μm to 1.2 μm.

[0019] Optionally, the first electrode group comprises a first electrode and a second electrode located at two ends of the first photosensitive unit, and the second electrode group comprises a third electrode and a fourth electrode located at two ends of the second photosensitive unit.

[0020] Optionally, the width of the first electrode, the second electrode, the third electrode and the fourth electrode is any value in a range from 500 nm to 800 nm.

[0021] According to the second aspect of the present application, the present application provides a spectrum analysis method based on the circular polariscope according to any one of the above, comprising the following steps:

[0022] calibrate a responsivity matrix of the left-handed chiral structure array and the right-handed chiral structure array in the circularly polarized photodetector;

[0023] emit monochromatic light to the circularly polarized photodetector according to a preset wavelength scanning;

[0024] synchronously collect left-handed response current and right-handed response current corresponding to the monochromatic light of each wavelength in the preset wavelength scanning;

[0025] calculate corresponding left-handed circularly polarized light intensity and right-handed circularly polarized light intensity according to the responsivity matrix, the left-handed response current and the right-handed response current.

[0026] The present application introduces a full-silicon-based circularly polarized photodetector with left-handed and right-handed chiral structures and electrical independence on the basis of spectral spectroscopy, and combines the light intensity response matrix to perform inversion calculation on the detection signal, thereby realizing synchronous and quantitative analysis of left-handed and right-handed components in the incident circularly polarized light at each monochromatic wavelength point, and overcoming the problems of inability to synchronously obtain left-handed and right-handed spectra, difficulty in quantitative separation of light intensity, and insufficient device stability and process compatibility in the prior art.

[0027] Further, the present application limits the thickness of the left-handed chiral structure and the right-handed chiral structure to the range of 110nm-130nm, so that it forms good optical resonance matching with the target working waveband, enhances chiral electromagnetic field coupling while ensuring the manufacturability of the structure, thereby improving the responsivity and selective differentiation ability to left-handed circularly polarized light and right-handed circularly polarized light.

[0028] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will describe the preferred embodiments of the present application in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] Some specific embodiments of the present application will be described in detail hereinafter with reference to the accompanying drawings, which are shown by way of example and not limitation. The same reference numbers in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0030] Figure 1 is a connection block diagram of a circularly polarized spectrometer according to an embodiment of the present application;

[0031] Figure 2 is a schematic overall structure diagram of a circularly polarized photodetector according to an embodiment of the present application;

[0032] Figure 3 is a schematic partial structure diagram of a circularly polarized photodetector according to an embodiment of the present application;

[0033] Figure 4 is a plot of the absorption CD of a circularly polarized photodetector for left and right circularly polarized light under the same power of left and right circularly polarized light incident according to an embodiment of the present application;

[0034] Figure 5 is a plot of the responsivity of a left-handed chiral structure array for left and right circularly polarized light under the same power of left and right circularly polarized light incident according to an embodiment of the present application;

[0035] Figure 6 is a plot of the responsivity of a right-handed chiral structure array for left and right circularly polarized light under the same power of left and right circularly polarized light incident according to an embodiment of the present application;

[0036] Figure 7 is a plot of the responsivity of a left-handed chiral structure array for left and right circularly polarized light under the same power of left and right circularly polarized light incident according to an embodiment of the present application;

[0037] Figure 8 is a schematic structural diagram of a left-handed chiral structure according to an embodiment of the present application;

[0038] Figure 9 is another schematic structural diagram of a left-handed chiral structure according to an embodiment of the present application;

[0039] Figure 10 is a schematic structural diagram of a right-handed chiral structure according to an embodiment of the present application;

[0040] Figure 11 is another schematic structural diagram of a right-handed chiral structure according to an embodiment of the present application;

[0041] Figure 12 is a plot of the optical field distribution of a left-handed chiral structure array under left circularly polarized light incident according to an embodiment of the present application;

[0042] Figure 13 is a plot of the optical field distribution of a left-handed chiral structure array under right circularly polarized light incident according to an embodiment of the present application;

[0043] Figure 14 is a schematic structural diagram of a left-handed chiral structure in Comparative Example 1;

[0044] Figure 15 is a schematic structural diagram of a right-handed chiral structure in Comparative Example 1;

[0045] Figure 16 is a plot of the absorption CD of a circularly polarized photodetector for left and right circularly polarized light under the same power of left and right circularly polarized light incident in Comparative Example 1; ​

[0046] Figure 17 is a curve graph of the response current of the left-handed chiral structure array of Comparative Example 1 under the left-handed circularly polarized light and the right-handed circularly polarized light under the incidence of the left-handed circularly polarized light of the same power;

[0047] Figure 18 is a schematic flow chart of the spectral analysis method according to an embodiment of the present application.

[0048] Reference signs:

[0049] 600 - circular polarization spectrometer, 500 - chiral sample to be measured, 400 - control module, 300 - laser emission module, 200 - spectral light splitting module, 100 - circular polarization photodetector, 10 - photosensitive layer, 20 - medium layer, 30 - chiral structure layer, 31 - left-handed chiral structure array, 32 - right-handed chiral structure array, 11 - first photosensitive unit, 12 - second photosensitive unit, 40 - first electrode group, 50 - first signal detection module, 60 - second electrode group, 70 - second signal detection module, 311 - left-handed chiral unit, 312 - left-handed chiral structure, 313 - vertical part, 314 - first bending part, 315 - second bending part, 316 - first arc-shaped edge, 317 - second arc-shaped edge, 321 - right-handed chiral unit, 322 - right-handed chiral structure, 324 - third bending part, 325 - fourth bending part, 326 - third arc-shaped edge, 327 - fourth arc-shaped edge, 318 - first end, 319 - second end, 41 - first electrode, 42 - second electrode, 61 - third electrode, 62 - fourth electrode. DETAILED DESCRIPTION

[0050] The specific embodiments of the present application will be further described in details below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0051] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in details below with reference to the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures. Based on the examples in the present application, all the other examples obtained by those skilled in the art without making creative efforts, fall within the scope of protection of the present application.

[0052] The terms "including", "containing", "having" and "encompassing" and any variations thereof herein are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or apparatus that includes a list of steps or units is not necessarily limited to those listed steps or units, but can optionally further include additional steps or units not listed, or can optionally further include other steps or units inherent to such processes, methods, products or apparatus.

[0053] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that the embodiments described herein are combinable with each other.

[0054] Figure 1 is a schematic block diagram of a circular polarization spectrometer according to an embodiment of the application, Figure 2 is a schematic overall structure diagram of a circular polarization photodetector according to an embodiment of the application, Figure 3 is a schematic partial structure diagram of a circular polarization photodetector according to an embodiment of the application, Figure 4 is a CD plot of the absorption of a circular polarization photodetector to left and right circularly polarized light under the incidence of left and right circularly polarized light of the same power according to an embodiment of the application, Figure 5 is a plot of the responsivity of an array of left-handed chiral structures to left and right circularly polarized light under the incidence of left and right circularly polarized light of the same power according to an embodiment of the application, Figure 6 is a plot of the responsivity of an array of right-handed chiral structures to left and right circularly polarized light under the incidence of left and right circularly polarized light of the same power according to an embodiment of the application, Figure 7 is a plot of the responsivity of an array of left-handed chiral structures to left and right circularly polarized light under the incidence of left and right circularly polarized light of the same power according to an embodiment of the application, is a plot of the responsivity of an array of left-handed chiral structures to left and right circularly polarized light under the incidence of left and right circularly polarized light of the same power according to an embodiment of the application, Figure 8 is a schematic structure diagram of a left-handed chiral structure according to an embodiment of the application, Figure 9 is another schematic structure diagram of a left-handed chiral structure according to an embodiment of the application, Figure 10 is a schematic structure diagram of a right-handed chiral structure according to an embodiment of the application, Figure 11 is another schematic structure diagram of a right-handed chiral structure according to an embodiment of the application, Figure 12 is a plot of the light field distribution of an array of left-handed chiral structures under the incidence of left circularly polarized light according to an embodiment of the application, Figure 13 is a plot of the light field distribution of an array of left-handed chiral structures under the incidence of right circularly polarized light according to an embodiment of the application,Figure 14 is a schematic structural diagram of the left-handed structure in Comparative Example 1, Figure 15 is a schematic structural diagram of the right-handed structure in Comparative Example 1, Figure 16 is a CD graph of the absorption of the circular polarization photodetector to the left and right circularly polarized light under the incidence of the left and right circularly polarized light with the same power in Comparative Example 1, Figure 17 is a graph of the response current of the left-handed structure array to the left and right circularly polarized light under the incidence of the left and right circularly polarized light with the same power in Comparative Example 1, Figure 18 is a schematic flow chart of a spectral analysis method according to an embodiment of the present application.

[0055] As shown in Figure 1 , the present application provides a circular polarization spectrometer 600 based on a full-silicon-based circular polarization photodetector 100, which includes a laser emission module 300, a spectral light splitting module 200, a circular polarization photodetector 100, and a control module 400. The excitation light generated by the laser emission module 300 irradiates the chiral sample 500 to be measured and generates circularly polarized light. The spectral light splitting module 200 receives the circularly polarized light and separates the circularly polarized light into monochromatic light of different wavelengths one by one. The circular polarization photodetector 100 receives monochromatic light of different wavelengths one by one and outputs corresponding left-handed response current and right-handed response current during the wavelength scanning process of the spectral light splitting module 200. The control module 400 combines the light intensity response matrix and the output left-handed response current and right-handed response current to calculate and obtain the left-handed circular polarization intensity and right-handed circular polarization intensity of the monochromatic light of the corresponding wavelength.

[0056] As shown in Figure 2 , in this embodiment, the circular polarization photodetector 100 includes a photosensitive layer 10, a dielectric layer 20, and a chiral structure layer 30 arranged in a stacked manner from bottom to top. The chiral structure layer 30 includes a left-handed chiral structure array 31 and a right-handed chiral structure array 32 which are independent and mirror-symmetric. The photosensitive layer 10 includes a first photosensitive unit 11 corresponding to the left-handed chiral structure array 31 and a second photosensitive unit 12 corresponding to the right-handed chiral structure array 32. The first photosensitive unit 11 is electrically connected to the first signal detection module 50 through the first electrode group 40, and the second photosensitive unit 12 is electrically connected to the second signal detection module 70 through the second electrode group 60, so as to output the left-handed response current through the first signal detection module 50 and the right-handed response current signal through the second signal detection module 70. The materials of the photosensitive layer 10 and the chiral structure layer 30 are silicon, and the material of the dielectric layer 20 is silicon dioxide.

[0057] The circular polarization photodetector is used to collect the left-handed response current and the right-handed response current signal under the monochromatic light of the same wavelength;

[0058] The circular polariscope calculates the left-handed circularly polarized light intensity and the right-handed circularly polarized light intensity according to the following formula:

[0059] Formula (1);

[0060] wherein, is the responsivity of the left-handed chiral structure array to the left-handed circularly polarized light, is the responsivity of the left-handed chiral structure array to the right-handed circularly polarized light, is the responsivity of the right-handed chiral structure array to the left-handed circularly polarized light, is the responsivity of the right-handed chiral structure array to the right-handed circularly polarized light, is the left-handed circularly polarized light intensity, is the right-handed circularly polarized light intensity, is the left-handed response current, is the right-handed response current.

[0061] In the embodiment, the different-wavelength monochromatic light separated by the spectral light splitting module 200 is received by the circular polarized photodetector 100 one by one. The monochromatic light at each wavelength is incident into the circular polarized photodetector 100. The top chiral structure layer 30 causes the left-handed chiral structure array 31 or the right-handed chiral structure array 32 to have stronger resonant coupling with the incident circularly polarized light of a specific handedness according to the geometric chirality of the left-handed or right-handed circularly polarized light, so as to have different transmittances to the left-handed circularly polarized light or the right-handed circularly polarized light. The circularly polarized light filtered by the chiral structure layer 30 is efficiently guided into the photosensitive layer 10 in the lower layer through the dielectric layer 20. The photosensitive layer 10 generates electron-hole pairs after absorbing photons. Under the action of an external electric field, the photo-generated carriers are rapidly separated and collected to form a photocurrent. Due to the polarization selectivity of the upper chiral structure layer 30 and the independent operation of the first photosensitive unit 11 and the second photosensitive unit 12 corresponding to the left-handed chiral structure array 31 and the right-handed chiral structure array 32, the generated light response current is simultaneously and independently output to the corresponding first signal detection module 50 and second signal detection module 70 through the respective first electrode group 40 and second electrode group 60, i.e., the left-handed response current and the right-handed response current corresponding to different-wavelength monochromatic light are respectively output. Finally, the left-handed response current and the right-handed response current corresponding to each wavelength point are collected and analyzed by the control module 400 in combination with the light intensity response matrix in Formula (1), so that the spectral light intensity information of the left-handed circularly polarized light and the right-handed circularly polarized light can be synchronously obtained.

[0062] In one embodiment, the laser emitting module 300 generates laser light which irradiates on the chiral sample 500 to be measured, and the chiral sample 500 generates circularly polarized light. The spectral light splitting module 200 separates the circularly polarized light generated by the chiral sample 500 into monochromatic light of different wavelengths one by one, so that the circularly polarized photodetector 100 can receive monochromatic light of different wavelengths one by one and output corresponding left-handed response current and right-handed response current during the wavelength scanning process of the spectral light splitting module 200. The control module 400 calculates the left-handed circularly polarized light intensity and the right-handed circularly polarized light intensity of monochromatic light at corresponding wavelengths based on the formula (1) and in combination with the left-handed response current output by the first signal detection module 50 and the right-handed response current output by the second signal detection module 70 of the circularly polarized photodetector 100. 、 、 and .

[0063] In this embodiment, after the left-handed circularly polarized light intensity and the right-handed circularly polarized light intensity at corresponding wavelengths are calculated, not only the synchronous reconstruction of left-handed and right-handed circularly polarized luminescence spectrum can be realized, but also the accurate quantification of circularly polarized degree, the spectral-level analysis of chiral luminescence characteristics, and the high-sensitivity detection of weak circularly polarized signals can be further realized, thereby significantly expanding the functional dimension and application scenarios of circularly polarized spectrum measurement.

[0064] In this embodiment, by introducing a full-silicon-based circularly polarized photodetector 100 with left-handed structure 312 and right-handed structure 322 and electrically independent on the basis of spectral light splitting, and by inversely calculating the detection signal in combination with the light intensity response matrix, the left-handed and right-handed components in the incident circularly polarized light are synchronously and quantitatively analyzed at each monochromatic wavelength point. The problems of the prior art, such as the inability to synchronously obtain left-handed and right-handed spectra, the difficulty in quantitatively separating light intensity, and the insufficient device stability and process compatibility, are overcome.

[0065] As Figure 4As shown, the incident of left-handed circularly polarized light and right-handed circularly polarized light with different wavelengths can obtain the CD (Circular Dichroism) value and wavelength relationship of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 respectively. Under the irradiation of left-handed circularly polarized light and right-handed circularly polarized light, the absorption of the left-handed chiral structure array 31 to the left-handed circularly polarized light is greater than that to the right-handed circularly polarized light in the wavelength band of 510nm-640nm, and the CD value can be up to 0.6, which is at a higher level. The absorption of the right-handed chiral structure array 32 to the right-handed circularly polarized light is greater than that to the left-handed circularly polarized light, which is basically opposite to the CD value of the left-handed chiral structure array 31, indicating that the silicon-based nano-chiral structure layer 30 used in the embodiment has a significant circularly polarized selective absorption ability in the visible light band, and the left-handed chiral structure 312 and the right-handed chiral structure 322 are mirror images of each other and have stable and reliable responses, which provides an important physical basis for realizing the synchronous and quantitative detection of left-handed circularly polarized light and right-handed circularly polarized light.

[0066] As shown in Figure 5 and Figure 6 , the left-handed circularly polarized light and the right-handed circularly polarized light with the same power are respectively incident on the left-handed chiral structure array 31 and the right-handed chiral structure array 32, and the response degree of the device is compared, wherein the response degree (R) is defined as:

[0067] Formula (2);

[0068] Wherein, Current is the size of the response current under the incident light, and P is the incident light power.

[0069] As shown in Figure 5 and Figure 6 , the response degree of the left-handed chiral structure array 31 to the left-handed circularly polarized light is greater than that to the right-handed circularly polarized light in the wavelength band of 510nm-640nm, and the highest response degree is about 27A / W. The response degree of the right-handed chiral structure array 32 to the right-handed circularly polarized light is greater than that to the left-handed circularly polarized light in the wavelength band of 510nm-640nm, and the highest response degree is about 28A / W. It is shown that in the all-silicon circularly polarized photodetector 100 in the embodiment, the left-handed chiral structure array 31 and the right-handed chiral structure array 32 respectively produce significantly enhanced photoelectric response to circularly polarized light of corresponding handedness, and maintain a high response degree level in the target wavelength band, which indicates that the chiral structure layer 30 can effectively distinguish the circular polarization state without sacrificing the photoelectric conversion efficiency. At the same time, the left-handed chiral structure array 31 and the right-handed chiral structure array 32 exhibit good complementarity and symmetry, which provides a stable and reliable physical basis for subsequent inversion of left-handed circularly polarized light and right-handed circularly polarized light intensity based on the light intensity response matrix.

[0070] According to Figure 5 andFigure 6 From the response curves shown, the differentiating factor of the response current of the circularly polarized photodetector 100 to the circularly polarized light can be obtained, which reflects the left-handed detection unit's value, wherein, is defined as:

[0071] Formula (3);

[0072] wherein, R L is the response size under left circularly polarized light irradiation, and R R is the response size under right circularly polarized light irradiation.

[0073] As Figure 7 shown, the photoelectric asymmetry factor of the circularly polarized photodetector 100 can be close to 1.97 at most, close to the theoretical limit value 2, which indicates that the circularly polarized photodetector 100 has extremely high selectivity and distinguishing ability to left and right circularly polarized light, can effectively suppress the cross response to non-target circularly polarized light, and significantly improves the accuracy and reliability of circularly polarized light intensity analysis.

[0074] As Figure 8 and Figure 9 shown, in a further embodiment, the left-handed chiral structure array 31 includes a plurality of left-handed chiral units 311 arranged at intervals along a first horizontal direction (with reference to direction b), and each left-handed chiral unit 311 includes a plurality of left-handed chiral structures 312 connected head-to-tail along a second horizontal direction (with reference to direction a), and each left-handed chiral structure 312 includes a vertical portion 313 extending along the second horizontal direction, and a first bending portion 314 and a second bending portion 315 protruding on both sides of the vertical portion 313 and being chiral symmetric, respectively, the first bending portion 314 has two first arc-shaped edges 316 connected to the side edges of the vertical portion 313 and parallel to each other, the two first arc-shaped edges 316 are spaced apart by a first preset distance L2, the second bending portion 315 has two second arc-shaped edges 317 connected to the side edges of the vertical portion 313 and parallel to each other, the two second arc-shaped edges 317 are spaced apart by a first preset distance L2, the first arc-shaped edge 316 and the second arc-shaped edge 317 are opposite in direction and have a first preset angle θ (with reference to direction a). Figure 2 Figure 2 Figure 9

[0075] As Figure 10 and Figure 11 shown, in the embodiment, the right-handed chiral structure array 32 includes a plurality of right-handed chiral units 321 arranged at intervals along a first horizontal direction (with reference to direction b), and each right-handed chiral unit 321 includes a plurality of right-handed chiral structures 322 connected head-to-tail along a second horizontal direction (with reference to direction a), and each right-handed chiral structure 322 includes a vertical portion 323 extending along the second horizontal direction, and a first bending portion 324 and a second bending portion 325 protruding on both sides of the vertical portion 323 and being chiral symmetric, respectively, the first bending portion 324 has two first arc-shaped edges 326 connected to the side edges of the vertical portion 323 and parallel to each other, the two first arc-shaped edges 326 are spaced apart by a second preset distance L3, the second bending portion 325 has two second arc-shaped edges 327 connected to the side edges of the vertical portion 323 and parallel to each other, the two second arc-shaped edges 327 are spaced apart by a second preset distance L3, the first arc-shaped edge 326 and the second arc-shaped edge 327 are opposite in direction and have a second preset angle φ (with reference to direction a). Figure 2 Figure 2 ​​​​The direction a) is a plurality of right-handed structures 322 connected head to tail, each right-handed structure 322 comprising a vertical part 313 extending along a second horizontal direction, and a third bending part 324 and a fourth bending part 325 respectively protruding on both sides of the vertical part 313 and being chiral symmetric, the third bending part 324 having two third arc-shaped edges 326 connected to the side edges of the vertical part 313 and parallel to each other, the fourth bending part 325 having a fourth arc-shaped edge 327 connected to the side edges of the vertical part 313 and parallel to each other, the two first arc-shaped edges 316 and the two second arc-shaped edges 317 are respectively spaced apart by a second preset distance L2, the third arc-shaped edges 326 and the fourth arc-shaped edges 327 are opposite in direction and have a second preset angle θ (refer to Figure 11 ), the fourth arc-shaped edge 327 has the same direction as the first arc-shaped edge 316, the second arc-shaped edge 317 and the third arc-shaped edge 326.

[0076] In the embodiment, by introducing arc-shaped edges on both sides of the vertical part 313 of the left-handed structure 312 or the right-handed structure 322, the left-handed structure 312 and the right-handed structure 322 form obviously different chiral electromagnetic resonance modes in space, thereby significantly enhancing the local field strength and absorption efficiency of the corresponding circularly polarized light in the target wave band, and suppressing the response to the opposite circularly polarized light.

[0077] In the embodiment, the performance of a single left-handed structure 312 or a single right-handed structure 322 can fluctuate sharply due to processing defects, and the use of an array composed of a plurality of left-handed structures 312 or right-handed structures 322 determines the overall performance by the statistical average effect of all structures, thereby reducing the processing precision requirement of a single left-handed structure 312 or a single right-handed structure 322. Moreover, the optical response of a single left-handed structure 312 or a single right-handed structure 322 is strongly dependent on the angle and alignment of the incident light, and a slight alignment deviation can cause a large deviation in the signal. An array with a certain area can spatially average the light spot. Even if the light spot has a certain divergence angle or is not completely vertically incident, there will always be some units in the array in an optimal working state, thereby enhancing the robustness of the circularly polarized light photodetector to non-ideal incident conditions.

[0078] As shown in Figure 12 and Figure 13 , the left-handed structure array 31 and the dielectric layer 20 can excite significantly different local electromagnetic field distributions when different circularly polarized light is incident, which indicates that the circularly polarized light photodetector 100 has obvious chiral selective light field regulation ability. Specifically, it produces stronger electric field local enhancement for circularly polarized light of the matching rotation direction, and the coupling for circularly polarized light of the opposite rotation direction is suppressed, thereby verifying the effective differentiation and selective response of the circularly polarized light photodetector 100 to left and right circularly polarized light at the light field level.

[0079] In a further embodiment, the radius of curvature R of the first arc-shaped edge 316, the second arc-shaped edge 317, the third arc-shaped edge 326, and the fourth arc-shaped edge 327 is any value between 100nm and 115nm, that is, the radius of curvature R of the first arc-shaped edge 316, the second arc-shaped edge 317, the third arc-shaped edge 326, and the fourth arc-shaped edge 327 can be 100nm, 105nm, 110nm, or 115nm, or any other value between 100nm and 115nm, and the first preset angle and the second preset angle ( Figure 9 The second preset angle (θ) is shown to be any value between 50° and 55°. That is, the first preset angle or the second preset angle can be 50°, 51°, 52°, 53°, 54°, or 55°, or any other value between 50° and 55°. In this embodiment, the limitation of the above-mentioned geometric parameter range further ensures a balance between chiral selectivity and photoelectric response intensity, enabling the left-handed chiral structure array 31 and the right-handed chiral structure array 32 to obtain higher circular dichroism and polarization resolution while maintaining high responsivity.

[0080] In a further embodiment, the vertical portion 313 includes a first end 318 and a second end 319. A first arc-shaped edge 316 and a fourth arc-shaped edge 327 are configured to bend toward the first end 318, and a second arc-shaped edge 317 and a third arc-shaped edge 326 are configured to bend toward the second end 319. The first end 318 and the second arc-shaped edge 317 are separated by a third preset distance L1, and the second end 319 and another second arc-shaped edge 317 are separated by a fourth preset distance L3. The first preset distance L2 and the second preset distance L2 are any values ​​between 110nm and 130nm, the third preset distance L1 is any value between 60nm and 75nm, the fourth preset distance is any value between 110nm and 140nm, and the width of the first end 318 and the second end 319 is any value between 50nm and 65nm. That is, the first preset distance or the second preset distance can be 110nm, 120nm, or 130nm, or any other value between 110nm and 130nm.

[0081] In this embodiment, the third preset distance L1 can be 60nm, 65nm, 70nm, or 75nm, or any other value between 60nm and 75nm. The fourth preset distance can be 110nm, 120nm, 130nm, or 140nm, or any other value between 110nm and 140nm. The widths of the first end 318 and the second end 319 can be 50nm, 55nm, 60nm, or 65nm, or any other value between 50nm and 65nm. By coordinating the bending direction of the arc-shaped edges at both ends of the vertical portion 313 and the key dimensional parameters, the spatial asymmetric electromagnetic coupling enhancement of the chiral structure is achieved, thereby significantly improving the selective absorption and photoelectric response difference of left-handed / right-handed circularly polarized light within the target wavelength band, and enhancing the circular polarization recognition capability and value.

[0082] In a further embodiment, the thickness of the left-handed structure 312 and the right-handed structure 322 is any value between 110 nm and 130 nm, that is, the thickness of the left-handed structure 312 and the right-handed structure 322 can be 110 nm, 120 nm, or 130 nm, or any other value between 110 nm and 130 nm. In this embodiment, by limiting the thickness of the left-handed structure 312 and the right-handed structure 322 to the range of 110 nm to 130 nm, a good optical resonance match is formed with the target operating wavelength. While ensuring the manufacturability of the structure, the chiral electromagnetic field coupling is enhanced, thereby improving the responsivity and selective discrimination capability for left-handed and right-handed circularly polarized light.

[0083] In a further embodiment, the thickness of the dielectric layer 20 is any value between 580nm and 620nm, and the thickness of the photosensitive layer 10 is any value between 1.1μm and 1.2μm. That is, the thickness of the dielectric layer 20 can be 580nm, 600nm, or 620nm, or any other value between 580nm and 620nm, and the thickness of the photosensitive layer 10 can be 1.1μm, 1.12μm, 1.14μm, 1.16μm, 1.18μm, or 1.2μm, or any other value between 1.1μm and 1.2μm. In this embodiment, by limiting the thickness of the dielectric layer 20 to the range of 580nm-620nm and the thickness of the photosensitive layer 10 to the range of 1.1μm-1.2μm, the light field between the chiral structure layer 30 and the photosensitive layer 10 is effectively modulated and enhanced, thereby improving the light absorption efficiency and carrier generation efficiency in the target wavelength band, and thus improving the sensitivity and signal-to-noise ratio of the circularly polarized photodetector 100.

[0084] like Figure 3 As shown, in a further embodiment, the first electrode group 40 includes a first electrode 41 and a second electrode 42 located at both ends of the first photosensitive unit 11, and the second electrode group 60 includes a third electrode 61 and a fourth electrode 62 located at both ends of the second photosensitive unit 12. The widths of the first electrode 41, the second electrode 42, the third electrode 61, and the fourth electrode 62 are any value between 500nm and 800nm. That is, the widths of the first electrode 41, the second electrode 42, the third electrode 61, and the fourth electrode 62 can be 500nm, 600nm, 700nm, or 800nm, or any other value between 500nm and 800nm. This is to reduce the obstruction of incident light and the light field disturbance by the electrodes while ensuring low series resistance and high carrier collection efficiency, thereby taking into account both electrical and optical performance and improving the stability and detection accuracy of the left and right rotation response currents.

[0085] In a further embodiment, the first signal detection module 50 and the second signal detection module 70 each comprise an ammeter and a nanowire connecting line for connecting the ammeter and the first electrode group 40 or the second electrode group 60, so that the electric signal generated by the first photosensitive unit 11 is transmitted to the nanowire connecting line in sequence through the first electrode 41 and the second electrode 42, and finally outputs a left-handed response current signal, while the electric signal generated by the second photosensitive unit 12 is transmitted to the nanowire connecting line in sequence through the third electrode 61 and the fourth electrode 62, and finally outputs a right-handed response current signal.

[0086] As shown in Figure 18 The present application provides a spectrum analysis method based on a circular polariscope 600, comprising the following steps:

[0087] Step S100: calibrating the responsivity matrix of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 in the circular polariscope 100;

[0088] Step S200: emitting monochromatic light to the circular polariscope 100 according to a preset wavelength scanning;

[0089] Step S300: synchronously collecting the left-handed response current and the right-handed response current corresponding to each wavelength of the monochromatic light in the preset wavelength scanning;

[0090] Step S400: calculating the corresponding left-handed circularly polarized light intensity and right-handed circularly polarized light intensity according to the responsivity matrix, the left-handed response current and the right-handed response current.

[0091] In the present embodiment, the circular polariscope 600 is calibrated by known single-wavelength left-handed circularly polarized light and right-handed circularly polarized light, the responsivity of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 under different circular polarization states is obtained, and the light intensity response matrix is established accordingly. Then, in the wavelength scanning process of the monochromator, the response currents of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 are synchronously collected at each preset wavelength point, and the light intensity components of the left-handed circularly polarized light and the right-handed circularly polarized light at the corresponding wavelength are obtained by inverse solution combined with the light intensity response matrix. The above analysis method can realize quantitative separation and analysis of circularly polarized light spectrum without additional polarization modulation or discrete optical elements, and has the advantages of simplified structure, high measurement efficiency, strong wavelength resolution capability and high circular polarization recognition accuracy.

[0092] In step S100, the circular polarimeter 600 is quantitatively calibrated by using single-wavelength left-handed circularly polarized light and right-handed circularly polarized light with known polarization states and known light intensities as standard inputs, and a one-to-one correspondence between the output electrical signals of the device and the light intensities of different circularly polarized light is accurately established. Specifically, through the above calibration process, not only can the real responsivity parameters of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 under left-handed circularly polarized light and right-handed circularly polarized light be obtained respectively, but also the influence of device structure differences, material non-uniformity and process deviations on the measurement results can be eliminated. In addition, a reliable and reversible physical basis for subsequent construction of the light intensity response matrix can be provided, so that in the case of unknown incident light polarization composition, stable and unique inverse solution can be performed based on the measured response current.

[0093] In step S200, the starting wavelength, the ending wavelength and the scanning step of the spectral light splitting module 200 are set, and the wavelength scanning is started. During the scanning process, for each preset wavelength point, the spectral light splitting module 200 is controlled to allow only monochromatic light of the corresponding wavelength to be incident on the circular polarimeter 600. Here, the spectral light splitting module 200 is a monochromator.

[0094] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0095] Embodiment 1

[0096] The circular polarization spectrometer 600 comprises the laser emission module 300, the spectral light splitting module 200, the circular polarization photodetector 100 and the control module 400, the excitation light generated by the laser emission module 300 irradiates the chiral sample 500 to be measured and generates circularly polarized light, the spectral light splitting module 200 receives the circularly polarized light and separates the circularly polarized light into monochromatic light of different wavelengths one by one, the circular polarization photodetector 100 receives the monochromatic light of different wavelengths one by one and outputs the corresponding left-handed response current and right-handed response current in the wavelength scanning process of the spectral light splitting module 200, and the control module 400 combines the light intensity response matrix and the output left-handed response current and right-handed response current to calculate the left-handed circularly polarized light intensity and right-handed circularly polarized light intensity of the corresponding wavelength monochromatic light. Wherein, the circular polarization photodetector 100 comprises a photosensitive layer 10, a dielectric layer 20 and a chiral structure layer 30 arranged in a stacked manner from bottom to top, the chiral structure layer 30 comprises a left-handed chiral structure array 31 and a right-handed chiral structure array 32 which are independent of each other, the photosensitive layer 10 comprises a first photosensitive unit 11 corresponding to the left-handed chiral structure array 31 and a second photosensitive unit 12 corresponding to the right-handed chiral structure array 32, and the first photosensitive unit 11 is electrically connected with the first signal detection module 50 through the first electrode group 40, and the second photosensitive unit 12 is electrically connected with the second signal detection module 70 through the second electrode group 60, so as to output the left-handed response current through the first signal detection module 50 and the right-handed response current signal through the second signal detection module 70, and the materials of the photosensitive layer 10 and the chiral structure layer 30 are silicon, and the material of the dielectric layer 20 is silicon dioxide.

[0097] Comparative Example 1

[0098] The difference between Comparative Example 1 and Example 1 is only that in the chiral structure layer 30 of the circular polarization photodetector 100, the first bending part 314 and the second bending part 315 of the left-handed chiral structure 312 are rectangular, and the third bending part 324 and the fourth bending part 325 of the right-handed chiral structure 322 are rectangular.

[0099] The circular dichroism and the photoelectric asymmetric factor of the circular polarization photodetector 100 in Comparative Example 1 are tested, and the test results are shown in Figure 16 and Figure 17

[0100] As shown in Figure 16 and Figure 17 ​As shown, under the same power of left and right circularly polarized light, the CD value of the left-handed chiral structure array 31 and the right-handed chiral structure array 32 of the circularly polarized photodetector 100 in Comparative Example 1 is about 0.3 in the wavelength range of 510nm-640nm, which is much lower than the CD value of the optimized circularly polarized photodetector 100. Similarly, in the wavelength range of 510nm-640nm, the left-handed chiral detection unit value of the circularly polarized photodetector 100 in Comparative Example 1 fluctuates significantly, and the maximum is only close to 1.5, which is obviously insufficient for distinguishing left and right circularly polarized light.

[0101] As shown in Figure 4 and Figure 7 , the left-handed chiral structure array 31 and the right-handed chiral structure array 32 of the circularly polarized photodetector 100 in Example 1 have CD values much higher than those of Comparative Example 1 in the wavelength range of 510nm-640nm, and the left-handed chiral detection unit value of the circularly polarized photodetector 100 in Example 1 is stably close to 1.97, which is also much higher than the value of the circularly polarized photodetector 100 in Comparative Example 1. This indicates that the circularly polarized photodetector 100 in Example 1 has extremely high selectivity and distinguishing ability for left and right circularly polarized light, and can significantly improve the accuracy and reliability of circularly polarized light intensity analysis.

[0102] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0103] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A circular polarization spectrometer based on an all-silicon-based circular polarization photodetector, characterized in that, The circular polarization photodetector of the circular polarization spectrometer comprises a photosensitive layer, a dielectric layer, and a chiral structure layer stacked sequentially from bottom to top. The chiral structure layer includes independent, mirror-symmetrical arrays of left-handed and right-handed chiral structures. The photosensitive layer includes a first photosensitive unit corresponding to the left-handed chiral structure array and a second photosensitive unit corresponding to the right-handed chiral structure array. The first photosensitive unit is electrically connected to a first signal detection module via a first electrode group, and the second photosensitive unit is electrically connected to a second signal detection module via a second electrode group. The first signal detection module outputs a left-handed response current, and the second signal detection module outputs a right-handed response current signal. The photosensitive layer and the chiral structure layer are made of silicon, and the dielectric layer is made of silicon dioxide. The left-handed chiral structure array includes a plurality of left-handed chiral units spaced apart along a first horizontal direction. Each left-handed chiral unit includes a plurality of left-handed structures connected end to end along a second horizontal direction. Each left-handed structure includes a vertical portion extending along the second horizontal direction and a first bent portion and a second bent portion protruding from both sides of the vertical portion and being chirally symmetrical. The first bent portion has two first arcuate sides connected to the side of the vertical portion and parallel to each other, with the two first arcuate sides spaced apart by a first preset distance. The second bent portion has two second arcuate sides connected to the side of the vertical portion and parallel to each other, with the two second arcuate sides spaced apart by a first preset distance. The first arcuate sides and the second arcuate sides have opposite orientations and have a first preset angle. The circularly polarized photodetector is used to collect the left-handed and right-handed response current signals under monochromatic light of the same wavelength; The circular polarization spectrometer calculates the intensity of left-handed and right-handed circularly polarized light according to the following formula: in, The responsivity of the left-handed chiral structure array to left-handed circularly polarized light is given. The responsivity of the left-handed chiral structure array to right-handed circularly polarized light is given. The responsivity of the right-handed chiral structure array to left-handed circularly polarized light is given. The responsivity of the right-handed chiral structure array to right-handed circularly polarized light is given. The intensity of left-handed circularly polarized light. The intensity of right-handed circularly polarized light. For left-handed response current, It is a right-handed response current.

2. The circular polarization spectrometer according to claim 1, characterized in that, The radius of curvature of the first arc-shaped edge and the second arc-shaped edge is any value between 100nm and 115nm, and the first preset angle is any value between 50° and 55°.

3. The circular polarization spectrometer according to claim 2, characterized in that, The vertical portion includes a first end and a second end. The first arc-shaped edge is configured to bend toward the first end, and the second arc-shaped edge is configured to bend toward the second end. The first end and the second arc-shaped edge are spaced apart by a third preset distance, and the second end and the other second arc-shaped edge are spaced apart by a fourth preset distance.

4. The circular polarization spectrometer according to claim 3, characterized in that, The first preset distance is any value between 110nm and 130nm, the third preset distance is any value between 60nm and 75nm, and the fourth preset distance is any value between 110nm and 140nm.

5. The circular polarization spectrometer according to claim 4, characterized in that, The thickness of the left-handed structure is any value between 110 nm and 130 nm.

6. The circular polarization spectrometer according to any one of claims 1-5, characterized in that, The thickness of the dielectric layer is any value between 580nm and 620nm, and the thickness of the photosensitive layer is any value between 1.1μm and 1.2μm.

7. The circular polarization spectrometer according to claim 6, characterized in that, The first electrode group includes a first electrode and a second electrode located at both ends of the first photosensitive unit, and the second electrode group includes a third electrode and a fourth electrode located at both ends of the second photosensitive unit.

8. The circular polarization spectrometer according to claim 7, characterized in that, The widths of the first electrode, the second electrode, the third electrode, and the fourth electrode are any values ​​between 500nm and 800nm.

9. A spectral analysis method based on a circular polarization spectrometer according to any one of claims 1-8, characterized in that, Includes the following steps: The responsivity matrices of the left-handed and right-handed chiral structure arrays in the circularly polarized photodetector are calibrated. Monochromatic light is emitted to the circularly polarized photodetector according to a preset wavelength scan. Simultaneously acquire the left-handed and right-handed response currents corresponding to the monochromatic light at each wavelength of the preset wavelength scan; The corresponding left-handed and right-handed circularly polarized light intensities are calculated based on the responsivity matrix, the left-handed response current, and the right-handed response current.

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