Method for realizing circular polarization degree detection of light through stress regulation and control

Abstract

The invention relates to a method for realizing circular polarization degree detection of light through stress regulation and control, and belongs to the technical field of polarization detection. According to the method, a Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate is used as a polarization detection device, and the linear polarization response of the polarization detection device is adjusted to be zero through external tensile stress exc. The ratio of the total light current to the background current under the positive and negative 45-degree incident angles when the tensile stress exc is applied and the corner of the quarter-wave plate are used as calibration data, and the circular polarization degree of the to-be-measured light is obtained by comparing the ratio of the total light current to the background current under the positive and negative 45-degree incident angles of the to-be-measured laser with the calibration data. The method is accurate in measurement result, simple, efficient, high in feasibility and beneficial to popularization and application in the future.

Description

Technical Field

[0001] The invention belongs to the technical field of polarization detection, and in particular relates to a method for realizing circular polarization degree detection of light through stress regulation. Background Art

[0002] Detection of the circular polarization degree of laser requires the use of materials that have a good response to circularly polarized light but not to linearly polarized light. However, most materials respond to both circularly polarized light and linearly polarized light, that is, they contain both circularly polarized photoinduced current (denoted as CPGE) and linearly polarized photoinduced current (denoted as LPGE), making it impossible to detect the circular polarization degree of laser. Therefore, it is necessary to find a method to adjust the linearly polarized photoinduced current of the material to zero or close to zero, while the CPGE current is not zero and the background current (i.e., current independent of polarization) does not increase significantly, so as to detect the circular polarization degree of light. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for detecting the circular polarization of light by stress regulation, that is, using a Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate as a polarization detection device, by applying an external tensile stress (denoted as e xc ) adjusts the linear polarization response of the device to zero. Applying tensile stress e xc The ratio of the total photocurrent to the background current at an incident angle of positive or negative 45 degrees is used as calibration data along with the rotation angle of the quarter-wave plate. By comparing the ratio of the total photocurrent to the background current of the laser to be measured at an incident angle of positive or negative 45 degrees with the calibration data, the circular polarization degree of the light to be measured is obtained.

[0004] To achieve the above purpose, the technical solution of the present invention is: a method for detecting the circular polarization degree of light through stress regulation, using a Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate as a polarization detection device to detect the circular polarization degree of the light to be measured.

[0005] In one embodiment of the present invention, by applying a tensile stress e xc The linear polarization response of the polarization detection device is adjusted to zero, and the circular polarization degree of the light to be measured is obtained by comparing the ratio of the total photocurrent to the background current of the light to be measured at an incident angle of plus or minus 45 degrees with the calibration data.

[0006] In one embodiment of the present invention, the tensile stress e is applied. xc The ratio of the total photocurrent to the background current at incident angles of ±45 degrees is used as calibration data along with the rotation angle of the quarter-wave plate.

[0007] In one embodiment of the present invention, the method comprises the following steps:

[0008] Step S1, evaporating a pair of gold electrodes with a thickness of 80 nm on the Bi2Te3 / Fe4GeTe2 heterojunction film, the electrode shape is a square with a side length of 0.5 mm, and the electrode spacing is 2.5 mm;

[0009] Step S2, installing the sample processed in step S1 in a vacuum Dewar flask, using a 1064nm laser as an excitation light source, allowing the laser to pass through a chopper, a polarizer, and a quarter-wave plate in sequence, and irradiating the midpoint of the line connecting the two electrodes on the sample at an incident angle of 45 degrees; the spot diameter is smaller than the distance between the two electrodes;

[0010] Step S3, rotate the quarter wave plate from 0 to 360 degrees, with a step length of 5 degrees, amplify the photocurrent at each quarter wave plate angle through a current amplifier and a phase-locked amplifier, and collect the current through a data acquisition card; fit the collected photocurrent using formula (1):

[0011]

[0012] in, is the rotation angle of the quarter-wave plate, I total is the total photocurrent measured, J CPGE is the circularly polarized photocurrent signal caused by circularly polarized light, L1 and L2 are linearly polarized photocurrent signals caused by linearly polarized light, and y0 is the background photocurrent caused by the thermoelectric effect and photovoltaic effect;

[0013] Step S4: bend the Bi2Te3 / Fe4GeTe2 heterojunction film and apply tensile stress along the sample surface. x ; Under different tensile stresses e x Step S3 is repeated to measure the circularly polarized photocurrent signal J under different stresses. CPGE , linearly polarized photocurrent signals L1 and L2, and find the linearly polarized photocurrent signal Close to zero, while the circularly polarized photocurrent signal J CPGE Non-zero tensile stress value e xc ;

[0014] Step S5: Applying a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film xc , repeat step S3 at incident angles ±45 degrees to measure the total photocurrent I under different laser powers total With the quarter wave plate corner The relationship curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is obtained by fitting the formula (1), that is, the change curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is measured, which is recorded as The different quarter wave plate angles are totalDivide by y0 to get I total The relationship curve between / y0 and the quarter wave plate rotation angle is used as calibration data and recorded as

[0015] Step S6, when the laser is incident vertically, the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film under different laser powers is measured to obtain a curve Q1 of the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film changing with the light power;

[0016] Step S7, irradiate the circularly polarized laser to be measured vertically on the Bi2Te3 / Fe4GeTe2 heterojunction film, measure the generated photoconductivity, compare the measured photoconductivity data with the photoconductivity versus optical power curve Q1 obtained in step S6, and obtain the optical power P1 of the laser to be measured;

[0017] Step S8, find the background current y0 corresponding to the light power P1 at an incident angle of ±45 degrees from the background photocurrent y0 versus light power variation curve measured in step S5, and record them as and

[0018] Step S9: Apply a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film xc , the photocurrent I generated by the Bi2Te3 / Fe4GeTe2 heterojunction film under the laser irradiation is measured at an incident angle of ±45 degrees. total , respectively and Will Divide by the background current at an incident angle of 45 degrees obtained in step S8 Get the value at 45 degree incident angle Will Divide by the background current at an incident angle of -45 degrees obtained in step S8 Get the -45 degree incident angle

[0019]

[0020] Step S10: The laser incident angles measured in step S5 are respectively ±45 degrees. The data of the quarter wave plate rotation angle is plotted for the ±45 degree incident angle. The curve of the change with the quarter wave plate rotation angle; then the 45 degree incident angle measured in step S9 and -45 degrees angle of incidence Also drawn on the figure, at this time under a 45 degree incident angle and -45 degrees angle of incidence are two parallel straight lines; At 45 degree incident angle The quarter-wave plate angles corresponding to the intersection points of the curves with the change of the quarter-wave plate angle are A1, A2, A3, and A4. At an incident angle of -45 degrees The quarter-wave plate angles corresponding to the intersection points of the curves with the change of the quarter-wave plate angle are B1, B2, B3, and B4, among which A1, A2, A3, and A4 will have a value equal to one of the values ​​of B1, B2, B3, and B4. This value is recorded as It is the circular polarization degree of the laser to be measured.

[0021] In one embodiment of the present invention, in step S1, an 80 nm gold electrode is evaporated on the Bi2Te3 / Fe4GeTe2 heterojunction film using electron beam evaporation technology.

[0022] In one embodiment of the present invention, in step S4, a stress device is used to bend the Bi2Te3 / Fe4GeTe2 heterojunction film.

[0023] In one embodiment of the present invention, in step S5, a tensile stress value e is applied to the Bi2Te3 / Fe4GeTe2 heterojunction film by a stress device. xc .

[0024] In one embodiment of the present invention, in step S9, a tensile stress value e is applied to the Bi2Te3 / Fe4GeTe2 heterojunction film by a stress device. xc .

[0025] In one embodiment of the present invention, the thickness of Bi2Te3 in the Bi2Te3 / Fe4GeTe2 heterojunction film in step S1 is 8nm.

[0026] In one embodiment of the present invention, the thickness of Fe4GeTe2 in the Bi2Te3 / Fe4GeTe2 heterojunction film in step S1 is 5 nm.

[0027] Compared with the prior art, the present invention has the following beneficial effects: the present invention can realize the measurement of the circular polarization degree of the light to be measured, and the measurement result is accurate, concise and efficient, and has high feasibility, which is conducive to future promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the experimental optical path of a preferred embodiment of the present invention.

[0029] Figure 2 Schematic diagram of an experimental device for applying stress used in a preferred embodiment of the present invention.

[0030] Figure 3is the circularly polarized photoinduced current J in the Bi2Te3 / Fe4GeTe2 heterojunction film in the preferred embodiment of the present invention. CPGE , the curves of linearly polarized photocurrent L1 and L2 changing with applied tensile stress.

[0031] Figure 4 1 is a curve showing the variation of photoconductivity with light power in a Bi2Te3 / Fe4GeTe2 heterojunction film in a preferred embodiment of the present invention, wherein the circles are experimental data and the solid line is a fitting curve.

[0032] Figure 5 In the preferred embodiment of the present invention, when the tensile stress e is applied xc =65e0, Bi2Te3 / Fe4GeTe2 heterojunction film at an incident angle of + / - 45 degrees and The curve of the change with the quarter wave plate rotation angle. The vertical dotted line represents and At an incident angle of positive or negative 45 degrees, there is a common intersection point, and the corresponding quarter-wave plate rotation angle is 20 degrees, so the circular polarization degree is sin(2×20°). DETAILED DESCRIPTION

[0033] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0034] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0036] The present invention provides a method for detecting the circular polarization of light by stress regulation, using a Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate as a polarization detection device, and applying a tensile stress e xc The linear polarization response of the polarization detection device is adjusted to zero, and the tensile stress e xcThe ratio of the total photocurrent to the background current at an incident angle of positive or negative 45 degrees is used as calibration data along with the rotation angle of the quarter wave plate. By comparing the ratio of the total photocurrent to the background current at an incident angle of positive or negative 45 degrees with the calibration data, the circular polarization degree of the light to be measured is obtained.

[0037] The following is the specific implementation process of the present invention.

[0038] like Figure 1-5 As shown, the present invention provides a method for detecting the circular polarization of light by stress regulation, wherein the Bi2Te3 / Fe4GeTe2 heterojunction used for detection is grown on an alumina substrate; the Bi2Te3 / Fe4GeTe2 heterojunction film is grown using a molecular beam epitaxy device; the method proposes a method for detecting the circular polarization of light by stress regulation of the Bi2Te3 / Fe4GeTe2 heterojunction film, and the specific steps are as follows:

[0039] Step S1, using electron beam evaporation technology to deposit a pair of gold electrodes with a thickness of 80 nm on the Bi2Te3 / Fe4GeTe2 heterojunction film, the electrode shape is a square with a side length of 0.5 mm, and the electrode spacing is about 2.5 mm;

[0040] Step S2, the sample is mounted in a vacuum Dewar flask, a 1064 nm laser is used as an excitation light source, the laser is sequentially passed through a chopper, a polarizer, and a quarter wave plate, and irradiated at the midpoint of the line connecting the two electrodes on the sample at an incident angle of 45 degrees; the spot diameter is smaller than the distance between the two electrodes;

[0041] Step S3, rotate the quarter wave plate from 0 to 360 degrees, with a step length of 5 degrees, amplify the photocurrent at each quarter wave plate angle through a current amplifier and a phase-locked amplifier, and collect the current through a data acquisition card; fit the collected photocurrent using the following formula (1):

[0042]

[0043] in, is the rotation angle of the quarter-wave plate, I total is the total photocurrent measured, J CPGE is the circularly polarized photocurrent signal caused by circularly polarized light, L1 and L2 are linearly polarized photocurrent signals caused by linearly polarized light, and y0 is the background photocurrent caused by the thermoelectric effect and photovoltaic effect;

[0044] Step S4: bend the Bi2Te3 / Fe4GeTe2 heterojunction film with a stress device, thereby applying a tensile stress e along the sample surface. x . Under different tensile stresses x Step S3 is repeated to measure the circularly polarized photocurrent signal J under different stresses.CPGE , linear polarization photocurrent signals L1 and L2. And find the linear polarization photocurrent signal Close to zero, while the circularly polarized photocurrent signal J CPGE Non-zero tensile stress value e xc .

[0045] Step S5: Apply a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film using a stress device xc , repeat step S3 at incident angles ±45 degrees to measure the total photocurrent I under different laser powers total With the quarter wave plate corner The relationship curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is obtained by fitting the formula (1). That is, the curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is measured. This data will be used as the calibration data and recorded as The different quarter wave plate angles are total Divide by y0 to get I total The relationship curve between / y0 and the quarter wave plate rotation angle is used as the calibration data and recorded as

[0046]

[0047] Step S6, when the laser is incident vertically, the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film under different laser powers is measured, thereby obtaining a curve Q1 of the change of the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film with the light power.

[0048] Step S7, irradiate the circularly polarized laser to be measured vertically on the Bi2Te3 / Fe4GeTe2 heterojunction film to measure the generated photoconductivity. Compare the measured photoconductivity data with the relationship curve Q1 between photoconductivity and optical power obtained in step S6 to obtain the optical power P1 of the laser to be measured.

[0049] Step S8: Find the background current y0 corresponding to the incident angle light power P1 of ±45 degrees from the background photocurrent y0 versus light power variation curve measured in step S5, and record them as and

[0050] Step S9: Apply a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film using a stress device xc , the photocurrent I generated by the Bi2Te3 / Fe4GeTe2 heterojunction film under the laser irradiation is measured at an incident angle of ±45 degrees. total , respectively and Will Divide by the background current at an incident angle of 45 degrees obtained in step S8 Get the value at 45 degree incident angle Will Divide by the background current at an incident angle of -45 degrees obtained in step S8 Get the -45 degree incident angle

[0051] Step S10: The laser incident angles measured in step S5 are respectively ±45 degrees. The data of the quarter wave plate rotation angle is plotted for the ±45 degree incident angle. Then the curve of the change with the quarter wave plate rotation angle is calculated. and -45 degrees angle of incidence Also drawn on the figure, at this time under a 45 degree incident angle and -45 degrees angle of incidence are two parallel straight lines. At 45 degree incident angle The quarter-wave plate angles corresponding to the intersection points of the curves with the change of the quarter-wave plate angle are A1, A2, A3, and A4. At an incident angle of -45 degrees The quarter wave plate angles corresponding to the intersection points of the curves with the change of the quarter wave plate angle are B1, B2, B3, and B4. Among them, A1, A2, A3, and A4 will have a value equal to one of the values ​​of B1, B2, B3, and B4. This value is recorded as this It is the circular polarization degree of the laser to be measured.

[0052] In this embodiment, in the Bi2Te3 / Fe4GeTe2 heterojunction film in step S1, the thickness of Bi2Te3 is 8 nm, and the thickness of Fe4GeTe2 is 5 nm.

[0053] In this embodiment, if Figure 1 The sample shown is a Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate using molecular beam epitaxy technology. The thickness of the Bi2Te3 film is 8nm, and the thickness of the Fe4GeTe2 film is 5nm. The 1064nm laser light power used is 100mw, and the spot diameter is about 0.8mm. The laser passes through the attenuator, chopper, polarizer, and quarter-wave plate in sequence, and then irradiates the midpoint of the line connecting the two electrodes of the sample. The frequency of the chopper is 229Hz.

[0054] Figure 2The schematic diagram of the experimental device for applying stress in the embodiment of the present invention is shown in FIG. The sample is attached to a polycarbonate rod with epoxy resin, and the polycarbonate rod is mounted on a steel stress table and supported by a pair of melamine foams. When the strain is applied with a differential sleeve, the polycarbonate rod bends and changes its shape into an arc, and the sample is stretched. The strain component includes e x (Stretch) and e z (Compression). Tensile strain component e x It can be expressed as e x =3hJ z / 2a 2 Where, h is the thickness of the polycarbonate rod, and 2a is the distance from the left edge to the right edge of the polycarbonate rod, which are denoted as A and B respectively. z The distance the stress needle moves forward is read from the differential sleeve. The compressive strain component e z It can be expressed as e z =-(C 12 / C 13 ) x Among them, C 12 and C 13 is the elastic constant of Bi2Te3 / Fe4GeTe2 heterojunction.

[0055] Figure 3 is the circularly polarized photoinduced current J in the Bi2Te3 / Fe4GeTe2 heterojunction film measured in the preferred embodiment of the present invention CPGE , linear polarization photocurrent L1 and L2 with the change of applied tensile stress. It can be seen that when the external transverse tensile stress e x When it is equal to 65e0, the linearly polarized photocurrents L1 and L2 are close to zero. is close to zero, while the circularly polarized photocurrent J CPGE is not zero, but still maintains a large value, which satisfies the condition for detecting the circular polarization degree of light. Therefore, in this embodiment, e xc =65e0. Among them, e0 is 3×10 -4 .

[0056] Figure 4 The curve of photoconductivity variation with light power in the Bi2Te3 / Fe4GeTe2 heterojunction film in the preferred embodiment of the present invention is shown in FIG. 1 , wherein the circles are experimental data and the solid line is a linear fitting curve. The data are measured without external stress. It can be seen that the photoconductivity increases linearly with the increase of light power. Therefore, by comparing the photoconductivity of the light to be measured with the curve of the photoconductivity variation with power, the light power of the light to be measured can be obtained.

[0057] Figure 5 In the preferred embodiment of the present invention, when the tensile stress e is applied xc =65e 0When, Bi 2 Te 3 / Fe 4 Get 2 Heterojunction film at an incident angle of ±45 degrees and The curve of the change with the quarter wave plate rotation angle. The vertical dotted line represents and The quarter wave plate rotation angle corresponding to the common intersection point at the incident angle of positive and negative 45 degrees is 20 degrees, so the circular polarization degree is sin(2×20°).

[0058] It can be seen from the above embodiments that the implementation of this embodiment is relatively convenient, concise and efficient, and the measurement is relatively accurate.

[0059] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for detecting the circular polarization of light by stress regulation, characterized in that: The Bi2Te3 / Fe4GeTe2 heterojunction film grown on a sapphire substrate is used as a polarization detection device to detect the circular polarization degree of the light to be measured.

2. The method for detecting the circular polarization degree of light by stress regulation according to claim 1, characterized in that: By applying tensile stress xc The linear polarization response of the polarization detection device is adjusted to zero, and the circular polarization degree of the light to be measured is obtained by comparing the ratio of the total photocurrent to the background current of the light to be measured at an incident angle of plus or minus 45 degrees with the calibration data.

3. The method for detecting the circular polarization degree of light by stress regulation according to claim 2, characterized in that: The tensile stress e xc The ratio of the total photocurrent to the background current at incident angles of ±45 degrees is used as calibration data along with the rotation angle of the quarter-wave plate.

4. A method for detecting the circular polarization degree of light by stress regulation according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: Step S1, evaporating a pair of gold electrodes with a thickness of 80 nm on the Bi2Te3 / Fe4GeTe2 heterojunction film, the electrode shape is a square with a side length of 0.5 mm, and the electrode spacing is 2.5 mm; Step S2, installing the sample processed in step S1 in a vacuum Dewar flask, using a 1064nm laser as an excitation light source, allowing the laser to pass through a chopper, a polarizer, and a quarter-wave plate in sequence, and irradiating the midpoint of the line connecting the two electrodes on the sample at an incident angle of 45 degrees; the spot diameter is smaller than the distance between the two electrodes; Step S3, rotate the quarter wave plate from 0 to 360 degrees, with a step length of 5 degrees, amplify the photocurrent at each quarter wave plate angle through a current amplifier and a phase-locked amplifier, and collect the current through a data acquisition card; fit the collected photocurrent using formula (1): in, is the rotation angle of the quarter-wave plate, I total is the total photocurrent measured, J CPGE is the circularly polarized photocurrent signal caused by circularly polarized light, L1 and L2 are linearly polarized photocurrent signals caused by linearly polarized light, and y0 is the background photocurrent caused by the thermoelectric effect and photovoltaic effect; Step S4: bend the Bi2Te3 / Fe4GeTe2 heterojunction film and apply tensile stress along the sample surface. x ; Under different tensile stresses e x Step S3 is repeated to measure the circularly polarized photocurrent signal J under different stresses. CPGE , linearly polarized photocurrent signals L1 and L2, and find the linearly polarized photocurrent signal Close to zero, while the circularly polarized photocurrent signal J CPGE Non-zero tensile stress value e xc ; Step S5: Applying a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film xc , repeat step S3 at incident angles ±45 degrees to measure the total photocurrent I under different laser powers total With the quarter wave plate corner The relationship curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is obtained by fitting the formula (1), that is, the change curve of the positive and negative background photocurrent y0 with the light power at the incident angle of ±45 degrees is measured, which is recorded as The different quarter wave plate angles are total Divide by y0 to get I total The relationship curve between / y0 and the quarter wave plate rotation angle is used as calibration data and recorded as Step S6, when the laser is incident vertically, the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film under different laser powers is measured to obtain a curve Q1 of the photoconductivity of the Bi2Te3 / Fe4GeTe2 heterojunction film changing with the light power; Step S7, irradiate the circularly polarized laser to be measured vertically on the Bi2Te3 / Fe4GeTe2 heterojunction film, measure the generated photoconductivity, compare the measured photoconductivity data with the photoconductivity versus optical power curve Q1 obtained in step S6, and obtain the optical power P1 of the laser to be measured; Step S8, find the background current y0 corresponding to the light power P1 at an incident angle of ±45 degrees from the background photocurrent y0 versus light power variation curve measured in step S5, and record them as and Step S9: Apply a tensile stress value e to the Bi2Te3 / Fe4GeTe2 heterojunction film xc , the photocurrent I generated by the Bi2Te3 / Fe4GeTe2 heterojunction film under the laser irradiation is measured at an incident angle of ±45 degrees. total , respectively and Will Divide by the background current at an incident angle of 45 degrees obtained in step S8 Get the value at 45 degree incident angle Will Divide by the background current at an incident angle of -45 degrees obtained in step S8 Get the -45 degree incident angle Step S10: The laser incident angles measured in step S5 are respectively ±45 degrees. The data of the quarter wave plate rotation angle is plotted for the ±45 degree incident angle. The curve of the change with the quarter wave plate rotation angle; then the 45 degree incident angle measured in step S9 and -45 degrees angle of incidence Also drawn on the figure, at this time under a 45 degree incident angle and -45 degrees angle of incidence are two parallel straight lines; At 45 degree incident angle The quarter-wave plate angles corresponding to the intersection points of the curves with the change of the quarter-wave plate angle are A1, A2, A3, and A4. At an incident angle of -45 degrees The quarter-wave plate angles corresponding to the intersection points of the curves with the change of the quarter-wave plate angle are B1, B2, B3, and B4, among which A1, A2, A3, and A4 will have a value equal to one of the values ​​of B1, B2, B3, and B4. This value is recorded as It is the circular polarization degree of the laser to be measured.

5. The method for detecting the circular polarization degree of light by stress regulation according to claim 4, characterized in that: In step S1, an 80 nm gold electrode is evaporated on the Bi2Te3 / Fe4GeTe2 heterojunction film using electron beam evaporation technology.

6. The method for detecting the circular polarization degree of light by stress regulation according to claim 4, characterized in that: In step S4, the Bi2Te3 / Fe4GeTe2 heterojunction film is bent by using a stress device.

7. The method for detecting the circular polarization degree of light by stress regulation according to claim 4, characterized in that: In step S5, a tensile stress value e is applied to the Bi2Te3 / Fe4GeTe2 heterojunction film by a stress device. xc .

8. The method for detecting the circular polarization degree of light by stress regulation according to claim 4, characterized in that: In step S9, a tensile stress value e is applied to the Bi2Te3 / Fe4GeTe2 heterojunction film by a stress device. xc .

9. The method for detecting circular polarization of light by stress regulation according to claim 1, characterized in that: The thickness of Bi2Te3 in the Bi2Te3 / Fe4GeTe2 heterojunction film in step S1 is 8nm.

10. The method for detecting the circular polarization degree of light by stress regulation according to claim 1, characterized in that: The thickness of Fe4GeTe2 in the Bi2Te3 / Fe4GeTe2 heterojunction film in step S1 is 5nm.

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