A polarization and wavelength combined detection method and device based on beam spin separation

Abstract

This application belongs to the field of optical measurement and discloses a method and apparatus for joint detection of polarization and wavelength based on beam spin separation. The method includes: in a first operating mode, the beam to be tested is incident on a geometric phase polarization grating, separating it into a zero-order diffraction spot containing the original polarization state and diffraction spots with left- and right-hand circular polarizations on either side; the ellipticity and direction of rotation of the beam to be tested are determined by measuring the light intensity of the two spots; a rotatable analyzer is placed behind the grating, and the polarization azimuth angle of the beam to be tested is determined by rotating the analyzer and measuring the change in the light intensity of the zero-order diffraction spot. In a second operating mode, a polarizer is placed in front of the grating to convert the beam to be tested into linearly polarized light; the light intensity of the separated zero-order diffraction spot and the diffraction spot on either side are measured; and the wavelength of the beam to be tested is determined based on the relationship between the intensity ratio and the wavelength. This method achieves integrated and efficient detection of all polarization parameters and wavelength of the beam, and is suitable for wide-band analysis.

Description

Technical Field

[0001] This invention relates to the field of optical measurement, and in particular to a method and apparatus for joint detection of polarization and wavelength based on beam spin separation. Background Technology

[0002] The polarization state and wavelength of light are two key properties describing the physical properties of a light beam. The polarization state is characterized by parameters such as ellipticity, rotation, and azimuth, reflecting the vibrational pattern of the electric vector of the light field in space; the wavelength is directly related to the energy of the light. Accurate detection of beam polarization and wavelength information has wide and important applications in remote sensing, biomedicine, industrial inspection, and materials analysis.

[0003] The photon spin-separation effect refers to the physical phenomenon where photons with different spin angular momentum separate laterally in space when propagating through a specific medium. This effect can be used to construct optical measurement systems that are closely related to the polarization state and wavelength of incident light.

[0004] However, traditional polarization and wavelength measurement techniques typically rely on multiple discrete optical components. For example, polarization state measurements often use the rotating waveplate method or the Stokes method, requiring multiple components such as waveplates and analyzers; wavelength measurements mainly depend on dispersive elements such as spectrometers. This multi-component approach results in large measurement systems with complex structures and cumbersome calibration and setup procedures. Furthermore, these traditional components are often designed to modulate or analyze only a single property of light, leading to a limited range of measurable optical parameters and restricted information dimensions. These problems significantly reduce the performance and feasibility of detecting multidimensional information of the light field in miniaturized, integrated systems, making it difficult to meet the core requirements of modern optical information measurement technology for wide-band applicability, high integration, dynamic response, and multi-parameter collaborative analysis.

[0005] Therefore, there is an urgent need in the existing technology for a solution that can overcome the above-mentioned defects, so as to realize a technical method for efficient, integrated and compact measurement of multiple optical properties of light beams, including polarization and wavelength. Summary of the Invention

[0006] Based on this, the purpose of this invention is to address the shortcomings of existing optical parameter measurement systems, such as large size, limited functionality, and low integration. It provides a method and device for joint detection of polarization and wavelength based on beam spin separation. This solution utilizes a single core component and achieves integrated and efficient detection of all polarization parameters and wavelength of the beam by switching operating modes.

[0007] In a first aspect, the present invention provides a method for joint detection of polarization and wavelength based on beam spin separation, comprising the following steps:

[0008] Polarization detection is performed in the first operating mode:

[0009] The light intensities of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test after passing through a geometric phase polarization grating are obtained; based on the light intensities of the first left spot and the first right spot, the ellipticity and rotation direction of the beam under test are determined.

[0010] The intensity of the first intermediate spot of the beam under test is obtained at different rotation angles of the analyzer after the beam under test passes through the geometric phase polarization grating and a rotatable analyzer; the polarization azimuth angle of the beam under test is determined based on the intensity of the first intermediate spot at different rotation angles.

[0011] Perform wavelength detection in the second operating mode:

[0012] A polarizer is placed in front of the optical path of the geometric phase polarization grating to convert the beam to be measured into linearly polarized light; the light intensities of the second left spot, the second middle spot and the second right spot formed by the diffraction of the linearly polarized light by the geometric phase polarization grating are obtained.

[0013] Based on the light intensity of the second intermediate spot and the light intensity of any side spot, and according to the relationship between phase delay and wavelength, the wavelength of the beam to be measured is determined.

[0014] As an optional embodiment of the first aspect of this application, in the step of performing polarization detection in the first operating mode, the electric field of the beam spot after diffraction by a geometrical phase polarization grating of the beam to be measured is expressed as follows: ;in This indicates the position of the beam under test in a three-dimensional rectangular coordinate system. The figure represents the electric field resulting from the spin separation of the beam under test after it passes through a geometric phase polarization grating. This represents the complex amplitude distribution of the electric field in the middle spot of the beam after it passes through a geometric phase polarization grating. These represent the complex amplitude distributions of the left- and right-hand circularly polarized electric fields after the optical spins of the beam under test are completely separated after passing through the geometric phase polarization grating. This represents the geometric phase factor obtained by passing the beam under test through a geometric phase polarization grating. This represents the spatial optical axis distribution of the geometric phase polarization grating. represents an imaginary number, This indicates that the intermediate spot of the beam under test, after passing through the geometric phase polarization grating, retains its original polarization state. This represents the phase difference between the fast and slow axes.

[0015] As an optional implementation of the first aspect of this application, the steps of determining the ellipticity and rotation direction of the beam to be measured specifically involve: substituting the light intensity of the first left-side light spot and the light intensity of the first right-side light spot into the ellipticity calculation formula to calculate the ellipticity; wherein, the ellipticity The calculation formula is: ;in, , This indicates that the light intensity of the first left-hand light spot is greater than that of the first right-hand light spot. This indicates that the electric field amplitude of the first left-side light spot is greater than that of the first right-side light spot; This indicates the light intensity of the first left-hand light spot. This indicates the light intensity of the first right-hand light spot. This represents the electric field amplitude of the first left-hand light spot. This represents the electric field amplitude of the first right-side light spot; based on the ellipticity... The sign of the light beam determines the direction of rotation of the beam under test, where a positive value indicates left-hand rotation and a negative value indicates right-hand rotation.

[0016] As an optional embodiment of the first aspect of this application, in the step of performing polarization detection in the first operating mode, the electric field of the beam spot after the beam to be measured passes through the geometric phase polarization grating and a rotatable analyzer is expressed as follows: ;in This indicates the position of the beam under test in a three-dimensional rectangular coordinate system. This indicates that the beam under test passes sequentially through a geometric phase polarization grating and a polarization direction of... The spin separation electric field of the polarizer; This represents the complex amplitude distribution of the electric field in the middle spot of the beam after it passes through a geometric phase polarization grating. These represent the complex amplitude distributions of the left- and right-hand circularly polarized electric fields after the optical spins of the beam under test are completely separated and passed through the analyzer. Indicates the direction of penetration. The Jones matrix of the analyzer, where the intensity of the first intermediate spot varies with the rotation angle of the analyzer. Change with change; This represents the phase factor obtained by passing the test beam through a geometric phase polarization grating and an analyzer. This represents the spatial optical axis distribution of the geometric phase polarization grating. represents an imaginary number, This indicates the intermediate spot obtained after the beam under test passes through a geometric phase polarization grating, which retains its original polarization state. This represents the phase difference between the fast and slow axes.

[0017] As an optional implementation of the first aspect of this application, the step of determining the polarization azimuth angle of the beam to be tested specifically involves: rotating the analyzer in a preset step size within a range of 0 to 180 degrees, and collecting the light intensity values ​​of the first intermediate spot at multiple rotation angles; determining the rotation angle corresponding to the maximum light intensity value, and using this rotation angle as the polarization azimuth angle of the beam to be tested.

[0018] As an optional embodiment of the first aspect of this application, the method further includes: when performing polarization detection, determining whether the beam under test forms only two separate light spots after diffraction by the geometric phase polarization grating; if so, removing the geometric phase polarization grating in the optical path and performing the step of determining the polarization azimuth angle of the beam under test.

[0019] As an optional embodiment of the first aspect of this application, in the step of performing wavelength detection in the second operating mode, the electric field of the light spot after the linearly polarized light is diffracted by the geometrical phase polarization grating is expressed as follows: ;in This represents the electric field that completely separates linearly polarized light after it passes through a horizontal analyzer, then through a geometric phase polarization grating, and finally through Fresnel diffraction. This represents the amplitude of the optical field after linearly polarized light passes through a horizontal analyzer and then through a geometric phase polarization grating to completely separate the polarized light. This represents the phase delay obtained by linearly polarized light after passing through a geometric phase polarization grating, where The linearly polarized electric field of the second intermediate light spot. represents an imaginary number, The right-hand circularly polarized electric field of the second light spot. This represents the phase factor obtained by passing linearly polarized light through a horizontal analyzer and then through a geometric phase polarization grating. This represents the left-hand circularly polarized electric field of the second light spot.

[0020] As an optional embodiment of the first aspect of this application, the step of determining the wavelength of the beam to be measured specifically comprises: calculating the ratio of the light intensity of the second intermediate spot to the measured total light intensity, wherein the measured total light intensity is the sum of the light intensity of the second intermediate spot and the light intensity of the spot measured on either side; based on the ratio, and according to the phase delay relationship of the beam to be measured... Geometric phase polarization grating phase delay The phase delay generated for calibration, The calibration wavelength of the geometric phase polarization grating is used; finally, the total light intensity is measured based on the intensity ratio of the intermediate spot. and phase delay relationship The wavelength of the beam under test was calculated. .

[0021] Secondly, embodiments of this application provide a polarization and wavelength joint detection device based on beam spin separation, comprising:

[0022] A geometric phase polarization grating is used to diffract and separate the beam under test.

[0023] An insertable or removable polarizer is disposed in front of the optical path of the geometric phase polarization grating;

[0024] A rotatable analyzer is disposed behind the optical path of the geometric phase polarization grating;

[0025] A light intensity detector is used to collect the light intensity of the light spot after passing through optical elements;

[0026] A processor, electrically connected to the light intensity detector, is configured to:

[0027] In the first operating mode, the light intensity detector is controlled to acquire the light intensity of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test after passing through the geometric phase polarization grating. Based on the light intensity, the ellipticity and rotation direction of the beam under test are determined. The light intensity of the first middle spot of the beam under test after passing through the geometric phase polarization grating and a rotatable analyzer is acquired at different rotation angles of the analyzer. Based on the light intensity of the first middle spot at different rotation angles, the polarization azimuth angle of the beam under test is determined.

[0028] In the second operating mode, after the polarizer is inserted into the optical path, the light intensity detector is controlled to acquire the light intensity of the second left spot, the second middle spot and the second right spot formed by the diffraction of linearly polarized light through the geometric phase polarization grating, and the wavelength of the beam to be measured is determined based on the relationship between the light intensity, phase delay and wavelength.

[0029] Thirdly, embodiments of this application provide an electronic device, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of the method described in the first aspect.

[0030] Fourthly, embodiments of this application provide a readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. High integration and compactness: This invention uses a single geometric phase polarization grating as the core component. By simply switching the operating mode (inserting / removing the polarizer), the measurement of two key parameters, polarization and wavelength, can be achieved, which greatly simplifies the system structure and reduces the size.

[0033] 2. Comprehensive functionality: This method can simultaneously measure all polarization parameters (ellipticity, rotation direction, azimuth angle) and wavelength of the beam under test, providing multi-dimensional analysis capabilities of beam properties.

[0034] 3. Wide band applicability: Based on the deterministic relationship between phase delay and wavelength, this method has good detection performance over a wide wavelength range and is highly applicable.

[0035] 4. Simple operation and high efficiency: The measurement process only requires a few light intensity acquisitions and simple rotation operations. The data processing algorithm is straightforward and clear, and the detection efficiency is high, making it suitable for dynamic or real-time monitoring scenarios. Attached Figure Description

[0036] Figure 1 This is a flowchart of a method for joint detection of polarization and wavelength based on beam spin separation according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of an experimental setup for a polarization detection mode of a beam spin-separation-based polarization and wavelength joint detection method according to an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the liquid crystal molecule distribution of a geometric phase polarization grating in an embodiment of the present invention, which is a method for joint detection of polarization and wavelength based on beam spin separation.

[0039] Figure 4 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is left-handed elliptically polarized light in an embodiment of the present invention.

[0040] Figure 5 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is left-handed circularly polarized light in an embodiment of the present invention.

[0041] Figure 6 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is right-hand circularly polarized light in an embodiment of the present invention.

[0042] Figure 7 This is a schematic diagram of an experimental setup for a wavelength detection mode of a beam spin-separation-based polarization and wavelength joint detection method according to an embodiment of the present invention.

[0043] Figure 8This is a schematic diagram showing the spatial distribution of the diffraction order spots of the beam under test completely separated after passing through the polarization and wavelength detection device in an embodiment of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] Example 1

[0047] Please see Figure 1 This is a flowchart illustrating a method for joint polarization and wavelength detection based on beam spin separation, provided by an embodiment of the present invention. The method may include the following steps:

[0048] S1: Obtain the light intensity of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test through a geometric phase polarization grating; determine the ellipticity and rotation direction of the beam under test based on the light intensity of the first left spot and the first right spot.

[0049] Figure 2 This is a schematic diagram of a polarization detection experimental device for an embodiment of a polarization and wavelength joint detection method based on beam spin separation; in step S1, the beam to be tested is modulated into arbitrary polarized light.

[0050] First, it should be noted that the initial wavelength of the beam to be measured is... The electric field expression is:

[0051] ;

[0052] in The electric field representing linearly polarized light. These represent the horizontal axis, vertical axis, and y-axis in a three-dimensional rectangular coordinate system, respectively. This represents the complex amplitude distribution of the electric field of the linearly polarized beam under test. They represent the left-hand circular polarization components, respectively. and right-hand circular polarization component ;

[0053] Then, by rotating the quarter-wave plate, the measured polarized light is modulated into a relatively arbitrary polarization state (the azimuth and ellipticity are not independent). The Jones matrix of the quarter-wave plate is as follows:

[0054] ;

[0055] in, The angle between the fast and slow axes of the quarter-wave plate and the rectangular coordinate axes. and These represent the sine and cosine operations of the optical axis distribution of a quarter-wave plate, respectively.

[0056] Jones matrix of the test beam with arbitrary polarization state obtained after quarter-wave plate modulation:

[0057] ;

[0058] The above formula can also be simplified as follows:

[0059] ;

[0060] in, This indicates that the transmission angle of a linearly polarized beam is... The electric field of a quarter-wave plate of degree 1000 This indicates that the transmission angle of a linearly polarized beam is... The complex amplitude distribution of the electric field of a quarter-wave plate of degree, wherein Represented by natural constant An exponential function with base 0. represents an imaginary number, This represents the rotation angle of the quarter-wave plate, where This represents the phase difference between the fast and slow axes.

[0061] To control the size of the light beam spot, a telescope system is added to adjust the spot size, using lens 1 and lens 2. The focal length of lens 1 is... The focal length of lens 2 is Place the two lenses coaxially, with a distance of [missing information]. Lens 1 is in front of lens 2. Therefore, the angular magnification is:

[0062] ;

[0063] The electric field representation of the beam under test after passing through the telescope system:

[0064] ;

[0065] in This represents the electric field of the beam after passing through the telescope system. This represents the amplitude distribution of the electric field of the beam passing through the telescope system.

[0066] In this embodiment, please refer to Figure 3 This is a schematic diagram of the liquid crystal molecule distribution of a geometric phase polarization grating in an embodiment of the present invention, based on a beam spin separation-based polarization and wavelength joint detection method. The Jones matrix of the geometric phase polarization grating is shown below.

[0067] ;

[0068] in, This represents the spatial optical axis distribution of the geometric phase polarization grating. Indicates the grating period, where This represents the phase delay of the beam under test after passing through the geometric phase polarization grating (where... ), and These represent the trigonometric function operations for the optical axis distribution.

[0069] In the first operating mode, the modulated polarized beam is incident on the geometric phase polarization grating, and the completely spin-separated spot is obtained through Fresnel far-field diffraction:

[0070] ;

[0071] in, The symbol represents the electric field resulting from the spin separation of an arbitrary polarized beam of light after it passes through a geometric phase polarization grating, with the beam size adjusted by a telescope system. This represents the complex amplitude distribution of the electric field after the arbitrary polarized beam under test has its spot size adjusted by the telescope system and then passes through a geometric phase polarization grating, resulting in complete spin separation. This represents the complex amplitude distribution of the electric field in the middle spot of an arbitrary polarized beam of light, after the beam size is adjusted by a telescope system and it passes through a geometric phase polarization grating, where the light spins are separated. These represent the complex amplitude distributions of the left-hand and right-hand circularly polarized electric fields after the arbitrary polarized beam under test, having passed through a geometric phase polarization grating with the spot size adjusted by the telescope system, achieving complete spin separation. Based on the geometric phase factor, the Jones matrices of the spin-separated left-hand circularly polarized light, right-hand circularly polarized light, and the light field of the intermediate spot are obtained from the observation formula:

[0072] ;

[0073] in, The arbitrary polarized beam to be tested is used to adjust the size of the light spot through a telescope system, and after passing through a geometrically phase-delayed polarization grating, it becomes left-handed circularly polarized light with spin separation. The arbitrary polarized beam to be tested is used to adjust the size of the beam spot through a telescope system, and after passing through a geometrically phase-delayed polarization grating, it becomes right-handed circularly polarized light with spin separation. The arbitrary polarized beam to be tested is adjusted in size by a telescope system and then passes through a geometrically phase-delayed polarization grating to form an intermediate beam with spin separation (whose polarization state is not modulated by the geometrically phase-delayed polarization grating).

[0074] For example, when dealing with left-handed elliptically polarized light, please refer to [link / reference]. Figure 4 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is left-handed elliptically polarized light in an embodiment of the present invention.

[0075] The light intensity of left-handed and right-handed circularly polarized light can be calculated using the light intensity formula.

[0076] ;

[0077] The intensity of spin-separated left-handed circularly polarized light. This represents the intensity of right-handed circularly polarized light with spin separation. The rotation angle of the quarter-wave plate. The wavelength of the beam to be measured is Phase delay under a geometric phase polarization grating.

[0078] Any polarization state can be synthesized from left-handed and right-handed components. Therefore, by using geometric phase delay to separate the left and right polarization of the beam under test, the intensity of the light spots on the left and right sides can be measured (left-handed polarized light is converted into right-handed polarized light by a geometric phase polarization grating and appears on the left side, and the same applies to right-handed polarization; therefore, the ratio of the left-handed to the right-handed component of the original beam can be expressed as the ratio of the left-hand spot to the right-hand spot). In actual measurements, extreme cases may occur when the beam under test is left-handed or right-handed circularly polarized light. Therefore, it is necessary to judge based on the light intensity phenomenon: left-handed circularly polarized light will have two spots on the left side, and right-handed circularly polarized light will also have two spots on the right side.

[0079] Please see Figure 5 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is left-handed circularly polarized light in an embodiment of the present invention. Figure 6 This is a schematic diagram of the polarization state of each spot after spin separation following the passing through a geometric phase liquid crystal polarization grating when the beam under test is right-handed circularly polarized light in an embodiment of the present invention.

[0080] In actual ellipticity measurements, the ellipticity measurement results of the polarization grating are expressed as follows:

[0081] ;

[0082] in, , This indicates that the light intensity of the first left-hand light spot is greater than that of the first right-hand light spot. This indicates that the electric field amplitude of the first left-side light spot is greater than that of the first right-side light spot; This indicates the light intensity of the first left-hand light spot. This indicates the light intensity of the first right-hand light spot. This represents the electric field amplitude of the first left-hand light spot. This represents the electric field amplitude of the first right-side light spot;

[0083] The above formula reveals that the rotation direction and ellipsoid of arbitrary polarized light modulated by a quarter-wave plate depend on the rotation angle of the quarter-wave plate. When A positive value indicates left-handed rotation. A negative value indicates right-handed rotation.

[0084] S2: Obtain the light intensity of the first intermediate spot at different rotation angles of the analyzer after the beam under test passes through the geometric phase polarization grating and a rotatable analyzer; determine the polarization azimuth angle of the beam under test based on the light intensity of the first intermediate spot at different rotation angles.

[0085] In this embodiment, an analyzer is added after the geometric phase polarization grating, and the Jones matrix of the analyzer is represented as follows:

[0086] ;

[0087] in Indicates the direction of penetration. The Jones matrix of the analyzer. Indicates the transmission axis of the analyzer and The included angle of the axis.

[0088] In the first operating mode, the spin-separated light spot passes through the polarization direction as follows: The optical field expression obtained by the polarizer of degree is:

[0089] ;

[0090] ;

[0091] in, This indicates that the beam under test passes sequentially through a quarter-wave plate and a geometric phase polarization grating, with the transmission and polarization directions being... The spin-separation electric field of the polarizer; where left and right circular polarizers... , The light intensity is reduced to half of its original value; the light spot in the middle... The light intensity varies with the rotation angle of the analyzer It changes with the changes. (Similarly, in this step of this embodiment, the left and right side light spots that are spin-separated refer to the first left side light spot and the first right side light spot, and the middle light spot that is spin-separated refers to the first middle light spot.)

[0092] In elliptical polarization, the polarization azimuth angle is related to the major axis of polarization. Since the polarization state of the central spot is not modulated by the geometric phase polarization grating to maintain its original polarization state, the central spot's polarization depends on the rotation angle of the analyzer. As the light intensity changes, the analyzer is rotated within the range of 0 to 180 degrees at the same time to measure the intermediate light intensity value and determine the maximum value and the corresponding angle, which is the azimuth angle of the beam to be measured.

[0093] Phase delay When the beam under test passes through the geometric phase polarization grating, only two spots appear. When measuring the azimuth angle, the geometric phase polarization grating needs to be removed from the optical path, and then the analyzer is rotated to measure the azimuth angle of the beam under test.

[0094] S3: A polarizer is placed in front of the optical path of the geometric phase polarization grating to convert the beam to be tested into linearly polarized light; the light intensities of the second left spot, the second middle spot, and the second right spot formed by the diffraction of the linearly polarized light by the geometric phase polarization grating are obtained; based on the light intensity of the second middle spot and the light intensity of any side spot, and according to the relationship between phase delay and wavelength, the wavelength of the beam to be tested is determined.

[0095] Please see Figure 7 This is a schematic diagram of an experimental setup for a wavelength detection mode using a beam spin separation-based polarization and wavelength joint detection method, as described in an embodiment of the present invention. First, it should be noted that the wavelength of the beam under test is... Calibration wavelength of a geometrically phase-delayed polarization grating At the calibrated wavelength, the dynamic phase delay of the geometrically phase-delayed polarization grating is: According to the dynamic phase formula:

[0096] ;

[0097] in This indicates the phase delay caused by the anisotropy of material molecules. The wavelength designed for a known geometric phase polarization grating. For the designed wavelength Phase delay. The thickness of the material molecules. This represents the difference in refractive index between the fast and slow axes of the polarization grating.

[0098] By observing the formula, it can be seen that a change in wavelength will lead to... Change, where the wavelength is changed Then the changing phase delay can be obtained. Represented as:

[0099] ;

[0100] In this embodiment, when measuring the wavelength of the beam under test in the second operating mode, the beam under test is added to a horizontal analyzer to make it horizontally polarized light, and then struck into a geometric phase polarization grating. The resulting spin-separated beam can be represented as follows:

[0101] ;

[0102] in This represents the electric field that completely separates linearly polarized light after it passes through a horizontal analyzer, then through a geometric phase polarization grating, and finally through Fresnel diffraction. This represents the amplitude of the optical field after linearly polarized light passes through a horizontal analyzer and then through a geometric phase polarization grating to completely separate the polarized light. This represents the phase delay obtained by linearly polarized light after passing through a geometric phase polarization grating. The electric field of the central light spot. It is a right-handed circularly polarized electric field. This represents the phase factor obtained by passing linearly polarized light through a horizontal analyzer and then through a geometric phase polarization grating. The electric field is a left-handed circularly polarized field (in this embodiment, the left and right side light spots that are spin-separated refer to the second left light spot and the second right light spot, and the middle light spot that is spin-separated refers to the second middle light spot).

[0103] Please see Figure 8 This is a schematic diagram showing the spatial distribution of the diffraction order spots of the beam under test completely separated after passing through the polarization and wavelength detection device in an embodiment of the present invention.

[0104] Furthermore, the formula for calculating light intensity is expressed as:

[0105] ;

[0106] in Indicates light intensity. Indicates that the electric field is Components in direction, Indicates that the electric field is Components in direction.

[0107] The electric field of the central light spot is represented as:

[0108] ;

[0109] in This represents the electric field of the central light spot. The amplitude of the electric field in the middle spot is denoted as .

[0110] The relationship between the light intensity of the central spot and the phase delay can be obtained from the light intensity formula as follows:

[0111] ;

[0112] The left-hand circularly polarized electric field on both sides is represented as:

[0113] ;

[0114] in This represents the electric field of the central light spot. The amplitude of the electric field is a left-handed circularly polarized field;

[0115] The relationship between the light intensity and phase delay of the left-hand circularly polarized electric field can be obtained from the light intensity formula as follows:

[0116] ;

[0117] Similarly, the intensity of the right-hand circularly polarized electric field on both sides is also expressed as:

[0118] ;

[0119] By observation, the light intensity of the left-handed light spot is equal to that of the right-handed light spot. Therefore, in the actual measurement of the light intensity of the light spot, the intensity of one of the two outer light spots and the intensity of the middle light spot are measured.

[0120] The measured light intensity of the light spot is expressed as follows:

[0121] ;

[0122] The ratio of the measured intensity of the central light spot to the measured total intensity is expressed as:

[0123] ;

[0124] In the above formula, The intensity of the measured intermediate light spot is compared to the total measured intensity.

[0125] According to the phase delay formula of the wavelength to be measured Then the relationship between wavelength and light intensity can be expressed as:

[0126] ;

[0127] In summary, this invention, through the ingenious design of two operating modes and utilizing the same core optical element—a geometrical phase polarization grating—successfully achieves comprehensive and integrated detection of all polarization parameters (ellipsoid, rotation, and azimuth) and wavelength of a light beam. This method is simple, highly efficient, and has broad application prospects in various fields such as precision industrial inspection, biomedical diagnostics, remote sensing and environmental monitoring, and optical education.

[0128] Example 2

[0129] The second embodiment of this application proposes a polarization and wavelength joint detection device based on beam spin separation, the device comprising:

[0130] A geometric phase polarization grating is used to diffract and separate the beam under test.

[0131] An insertable or removable polarizer is disposed in front of the optical path of the geometric phase polarization grating;

[0132] A rotatable analyzer is disposed behind the optical path of the geometric phase polarization grating;

[0133] A light intensity detector is used to collect the light intensity of the light spot after passing through optical elements;

[0134] A processor, electrically connected to the light intensity detector, is configured to:

[0135] In the first operating mode, the light intensity detector is controlled to acquire the light intensity of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test after passing through the geometric phase polarization grating. Based on the light intensity, the ellipticity and rotation direction of the beam under test are determined. The light intensity of the first middle spot of the beam under test after passing through the geometric phase polarization grating and a rotatable analyzer is acquired at different rotation angles of the analyzer. Based on the light intensity of the first middle spot at different rotation angles, the polarization azimuth angle of the beam under test is determined.

[0136] In the second operating mode, after the polarizer is inserted into the optical path, the light intensity detector is controlled to acquire the light intensity of the second left spot, the second middle spot and the second right spot formed by the diffraction of linearly polarized light through the geometric phase polarization grating, and the wavelength of the beam to be measured is determined based on the relationship between the light intensity, phase delay and wavelength.

[0137] The polarization and wavelength joint detection device based on beam spin separation in this application embodiment can be a system, or a component, integrated circuit, or chip in a terminal. The device can be a mobile electronic device or a non-mobile electronic device. For example, mobile electronic devices can be mobile phones, tablets, laptops, PDAs, in-vehicle electronic devices, wearable devices, ultra-mobile personal computers (UMPCs), netbooks, or personal digital assistants (PDAs), etc., while non-mobile electronic devices can be servers, network-attached storage (NAS), personal computers (PCs), etc. This application embodiment does not impose specific limitations.

[0138] The polarization and wavelength joint detection device based on beam spin separation in this application embodiment can be a device with an operating system. This operating system can be Android, iOS, or other possible operating systems; this application embodiment does not specifically limit it.

[0139] The polarization and wavelength joint detection device based on beam spin separation provided in this application embodiment can achieve... Figure 1 The various processes implemented by the polarization and wavelength joint detection method based on beam spin separation in the method embodiment are not described in detail here to avoid repetition.

[0140] Optionally, embodiments of this application also provide an electronic device, including a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the various processes of the above-described embodiment of a method for joint detection of polarization and wavelength based on beam spin separation, and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0141] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described embodiment of a polarization and wavelength joint detection method based on beam spin separation, and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0142] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0143] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0144] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0145] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for joint polarization and wavelength detection based on beam spin separation, characterized in that, Includes the following steps: Polarization detection is performed in the first operating mode: The light intensities of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test after passing through a geometric phase polarization grating are obtained; based on the light intensities of the first left spot and the first right spot, the ellipticity and rotation direction of the beam under test are determined. The intensity of the first intermediate spot of the beam under test is obtained at different rotation angles of the analyzer after the beam under test passes through the geometric phase polarization grating and a rotatable analyzer; the polarization azimuth angle of the beam under test is determined based on the intensity of the first intermediate spot at different rotation angles. Perform wavelength detection in the second operating mode: A polarizer is placed in front of the optical path of the geometric phase polarization grating to convert the beam to be measured into linearly polarized light; the light intensities of the second left spot, the second middle spot and the second right spot formed by the diffraction of the linearly polarized light by the geometric phase polarization grating are obtained. Based on the light intensity of the second intermediate spot and the light intensity of any side spot, and according to the relationship between phase delay and wavelength, the wavelength of the beam to be measured is determined.

2. The method according to claim 1, characterized in that, In the polarization detection step performed in the first operating mode, the electric field of the beam spot after diffraction by a geometric phase polarization grating is expressed as: ； in This indicates the position of the beam under test in a three-dimensional rectangular coordinate system. The figure represents the electric field resulting from the spin separation of the beam under test after it passes through a geometric phase polarization grating. This represents the complex amplitude distribution of the electric field in the middle spot of the beam after it passes through a geometric phase polarization grating. These represent the complex amplitude distributions of the left- and right-hand circularly polarized electric fields after the optical spins of the beam under test are completely separated after passing through the geometric phase polarization grating. This represents the geometric phase factor obtained by passing the beam under test through a geometric phase polarization grating. This represents the spatial optical axis distribution of the geometric phase polarization grating. represents an imaginary number, This indicates that the intermediate spot of the beam under test, after passing through the geometric phase polarization grating, retains its original polarization state. This represents the phase difference between the fast and slow axes.

3. The method according to claim 2, characterized in that, The specific steps for determining the ellipticity and rotation direction of the beam under test are as follows: Substitute the light intensity of the first left light spot and the light intensity of the first right light spot into the ellipticity calculation formula to calculate the ellipticity; wherein, the ellipticity The calculation formula is: ； in, , This indicates that the light intensity of the first left-hand light spot is greater than that of the first right-hand light spot. This indicates that the electric field amplitude of the first left-side light spot is greater than that of the first right-side light spot; This indicates the light intensity of the first left-hand light spot. This indicates the light intensity of the first right-hand light spot. This represents the electric field amplitude of the first left-hand light spot. This represents the electric field amplitude of the first right-side light spot; According to the ellipticity The sign of the light beam determines the direction of rotation of the beam under test, where a positive value indicates left-hand rotation and a negative value indicates right-hand rotation.

4. The method according to claim 1, characterized in that, In the polarization detection step performed in the first operating mode, the electric field of the beam after passing through the geometric phase polarization grating and a rotatable analyzer is expressed as: ； in This indicates the position of the beam under test in a three-dimensional rectangular coordinate system. This indicates that the beam under test passes sequentially through a geometric phase polarization grating and a polarization direction of... The spin separation electric field of the polarizer; This represents the complex amplitude distribution of the electric field in the middle spot of the beam after it passes through a geometric phase polarization grating. These represent the complex amplitude distributions of the left- and right-hand circularly polarized electric fields after the optical spins of the beam under test are completely separated and passed through the analyzer. Indicates the direction of penetration. The Jones matrix of the analyzer, where the intensity of the first intermediate spot varies with the rotation angle of the analyzer. Change with change; This represents the phase factor obtained by passing the test beam through a geometric phase polarization grating and an analyzer. This represents the spatial optical axis distribution of the geometric phase polarization grating. represents an imaginary number, This indicates the intermediate spot obtained after the beam under test passes through a geometric phase polarization grating, which retains its original polarization state. This represents the phase difference between the fast and slow axes.

5. The method according to claim 4, characterized in that, The specific steps for determining the polarization azimuth angle of the beam to be measured are as follows: The analyzer is rotated in a preset step size within a range of 0 to 180 degrees, and the light intensity value of the first intermediate spot is collected at multiple rotation angles. Determine the rotation angle corresponding to the maximum light intensity value, and use this rotation angle as the polarization azimuth angle of the beam under test.

6. The method according to claim 5, characterized in that, The method further includes: During polarization detection, it is determined whether the beam under test forms only two separate spots after being diffracted by the geometric phase polarization grating; If so, the geometric phase polarization grating is removed from the optical path, and the step of determining the polarization azimuth angle of the beam to be measured is performed.

7. The method according to claim 1, characterized in that, In the wavelength detection step performed in the second operating mode, the electric field of the light spot after diffraction by the geometric phase polarization grating of the linearly polarized light is expressed as: ； in This represents the electric field that completely separates linearly polarized light after it passes through a horizontal analyzer, then through a geometric phase polarization grating, and finally through Fresnel diffraction. This represents the amplitude of the optical field after linearly polarized light passes through a horizontal analyzer and then through a geometric phase polarization grating to completely separate the polarized light. This represents the phase delay obtained by linearly polarized light after passing through a geometric phase polarization grating, where The linearly polarized electric field of the second intermediate light spot. represents an imaginary number, The right-hand circularly polarized electric field of the second light spot. This represents the phase factor obtained by passing linearly polarized light through a horizontal analyzer and then through a geometric phase polarization grating. This represents the left-hand circularly polarized electric field of the second light spot.

8. The method according to claim 7, characterized in that, The specific steps for determining the wavelength of the beam to be measured are as follows: Calculate the ratio of the light intensity of the second intermediate light spot to the measured total light intensity, wherein the measured total light intensity is the sum of the light intensity of the second intermediate light spot and the light intensity of the light spot measured on any side; Based on the ratio, and according to the phase delay relationship of the beam under test. Geometric phase polarization grating phase delay The phase delay generated for calibration, The calibration wavelength of the geometric phase polarization grating; Finally, the total light intensity was measured based on the light intensity ratio of the central light spot. and phase delay relationship The wavelength of the beam under test was calculated. .

9. A polarization and wavelength joint detection device based on beam spin separation, characterized in that, include: A geometric phase polarization grating is used to diffract and separate the beam under test. An insertable or removable polarizer is disposed in front of the optical path of the geometric phase polarization grating; A rotatable analyzer is disposed behind the optical path of the geometric phase polarization grating; A light intensity detector is used to collect the light intensity of the light spot after passing through optical elements; A processor, electrically connected to the light intensity detector, is configured to: In the first operating mode, the light intensity detector is controlled to acquire the light intensity of the first left spot, the first middle spot, and the first right spot formed by the diffraction of the beam under test after passing through the geometric phase polarization grating. Based on the light intensity, the ellipticity and rotation direction of the beam under test are determined. The light intensity of the first middle spot of the beam under test after passing through the geometric phase polarization grating and a rotatable analyzer is acquired at different rotation angles of the analyzer. Based on the light intensity of the first middle spot at different rotation angles, the polarization azimuth angle of the beam under test is determined. In the second operating mode, after the polarizer is inserted into the optical path, the light intensity detector is controlled to acquire the light intensity of the second left spot, the second middle spot and the second right spot formed by the diffraction of linearly polarized light through the geometric phase polarization grating, and the wavelength of the beam to be measured is determined based on the relationship between the light intensity, phase delay and wavelength.

10. An electronic device, characterized in that, It includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of a polarization and wavelength joint detection method based on beam spin separation as described in any one of claims 1-8.

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