Polarization modulation assembly, laser power stabilizer and polarization modulation method

Abstract

The embodiment of the invention provides a polarization modulation assembly, a laser power stabilizer and a polarization modulation method, and relates to the technical field of laser. The polarization modulation assembly comprises a polarization grating, a lens, a phase delay wave plate and a reflector which are sequentially arranged, the polarization grating can split incident linearly polarized light into left-handed polarized light and right-handed polarized light, and the left-handed polarized light and the right-handed polarized light sequentially pass through the lens and the phase delay wave plate and then are incident to the reflector. The left-handed polarized light and the right-handed polarized light are reflected to the polarization grating through the reflector, the left-handed polarized light and the right-handed polarized light which are focused and reflected are combined through the polarization grating to obtain modulated polarized light, the response speed is high through the polarization grating, the polarization state of light can be accurately controlled, and laser modulation is achieved. In addition, the polarization modulation assembly provided by the embodiment of the invention is simple in structure, and is suitable for various scenes where the laser power needs to be rapidly adjusted.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a polarization modulation component, a laser power stabilizer and a polarization modulation method. Background Art

[0002] In today's high-precision processing field, laser technology plays an indispensable role, and its application in production, scientific research, medical treatment and other fields is becoming more and more extensive. In these fields, the stability of the laser is crucial to ensure processing quality, improve experimental accuracy and ensure medical safety.

[0003] In the prior art, the purpose of stabilizing laser power is usually achieved by adjusting the polarization state of the input laser. The basic idea of ​​this solution is to adjust the power level of the output laser by controlling the polarization direction of the input laser. For example, the polarization direction of the input laser is adjusted by rotating a half-wave plate, and then the transmitted light is separated by a polarization beam splitter as the output laser to adjust the output laser power. In the above solution, the response speed of adjusting the laser power by rotating the half-wave plate is slow, and the device is large in size, so it cannot be used in scenarios where rapid adjustment of laser power is required. Summary of the invention

[0004] In order to at least overcome the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a polarization modulation component, a laser power stabilizer and a polarization modulation method.

[0005] In a first aspect, an embodiment of the present application provides a polarization modulation component, wherein the polarization modulation component includes a polarization grating, a lens, a phase delay wave plate, and a reflector arranged in sequence;

[0006] The polarization grating is used to split the incident linear polarized light into left-handed polarized light and right-handed polarized light, and the left-handed polarized light and the right-handed polarized light are incident on the reflector after passing through the lens and the phase delay wave plate in sequence, wherein the phase delay wave plate is used to adjust the polarization state of the light;

[0007] The reflector is used to reflect the left-handed polarized light and the right-handed polarized light, and the reflected left-handed polarized light and the right-handed polarized light are incident on the lens after passing through the phase delay wave plate in sequence, and the lens is used to focus the reflected left-handed polarized light and the right-handed polarized light;

[0008] The polarization grating is also used to combine the left-handed polarized light and the right-handed polarized light after focusing and reflection to obtain modulated output light.

[0009] In a possible implementation, the polarization grating and the reflector are respectively located on opposite sides of the lens, the distance between the polarization grating and the lens is equal to the focal length of the lens, and the distance between the reflector and the lens is equal to the focal length of the lens.

[0010] In a possible implementation manner, the plane where the polarization grating is located includes a first direction and a second direction that are perpendicular to each other;

[0011] The polarization grating extends along the first direction. When the polarization grating moves along the second direction, the light intensity of the emergent light changes periodically with the relative displacement of the polarization grating.

[0012] In a possible implementation, the phase delay wave plate includes a quarter wave plate.

[0013] In a second aspect, an embodiment of the present application further provides a laser power stabilizer, comprising a first light splitting component, a second light splitting component, a detection component, a control component, and a polarization modulation component described in any one of the first aspects;

[0014] The polarization modulation component is connected to the first light splitting component and the control component respectively, and is used to modulate the polarization direction of the input laser;

[0015] The first beam splitter is used to split the output beam of the polarization modulation component to obtain a first polarized laser beam as a main loop beam and a second polarized laser beam as a branched beam;

[0016] The second light splitting component is used to split the first polarized laser to obtain a branch light beam;

[0017] The detection component is connected to the second light splitting component, and is used to detect the light intensity of the branch light beam and send the detection result to the control component;

[0018] The control component is connected to the detection component to form a main loop for receiving the detection result of the detection component and adjusting the polarization modulation component according to the detection result to adjust the light intensity of the first polarized laser to the target light intensity.

[0019] In a possible implementation, the first beam splitting component includes a polarization beam splitter, the first polarized laser light and the second polarized laser light split by the polarization beam splitter are linearly polarized light, and polarization directions of the first polarized laser light and the second polarized laser light are perpendicular to each other.

[0020] In one possible implementation, the second beam splitting component includes a beam splitting mirror, a beam splitting prism and / or a reflector arranged in sequence in the light incident direction, and the second beam splitting component is used to split the first polarized laser to obtain a transmitted beam and a reflected beam, and use the beam with smaller light intensity between the transmitted beam and the reflected beam as the split beam.

[0021] In a possible implementation, the plane where the polarization grating in the polarization modulation component is located includes a first direction and a second direction that are perpendicular to each other, wherein the second direction is the same as an extension direction of the grating in the polarization grating;

[0022] The control component is used to control the polarization grating to move linearly along the first direction according to the detection result, and the light intensity of the first polarized laser changes periodically with the displacement of the polarization grating.

[0023] In a third aspect, an embodiment of the present application further provides a polarization modulation method, which is applied to the polarization modulation component in any one of the first aspects, and the method includes:

[0024] Splitting incident linearly polarized light into left-handed polarized light and right-handed polarized light via the polarization grating;

[0025] Before the left-handed polarized light and the right-handed polarized light return to the polarization grating via the lens, the phase delay wave plate and the reflector in sequence, the polarization direction of the incident linear polarized light is modulated by the polarization grating to achieve the target output light intensity.

[0026] In a possible implementation, the plane where the polarization grating in the polarization modulation component is located includes a first direction and a second direction perpendicular to each other, wherein the second direction is the same as the extension direction of the grating in the polarization grating, and the step of modulating the polarization direction of the incident linear polarized light by the polarization grating before the left-handed polarized light and the right-handed polarized light successively pass through the lens, the phase delay wave plate, and the reflector and return to the polarization grating along the original path to achieve the target output light intensity includes:

[0027] Before the left-handed polarized light and the right-handed polarized light return to the polarization grating along the original path after passing through the lens, the phase delay wave plate and the reflector in sequence, the polarization grating is moved along the first direction according to the intensity of the target output light, and the intensity of the target output light changes periodically with the displacement of the polarization grating.

[0028] Based on any of the above aspects, the polarization modulation component, laser power stabilizer and polarization modulation method provided in the embodiments of the present application include a polarization grating, a lens, a phase delay wave plate and a reflector arranged in sequence, the polarization grating can split the incident linear polarized light into left-handed polarized light and right-handed polarized light, the left-handed polarized light and the right-handed polarized light are incident on the reflector after passing through the lens and the phase delay wave plate in sequence, the left-handed polarized light and the right-handed polarized light are reflected to the polarization grating through the reflector, and the polarization grating combines the left-handed polarized light and the right-handed polarized light after the focused reflection to obtain the modulated polarized light, wherein the polarization grating not only has a fast response speed, but also can accurately control the polarization state of the light to achieve modulation of the laser. In addition, the polarization modulation component provided in the embodiments of the present application has a simple structure and is suitable for a variety of scenarios that require rapid adjustment of the laser power. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 A schematic diagram of the structure of a polarization modulation component provided in an embodiment of the present application;

[0031] Figure 2 for Figure 1 A schematic diagram of a local structure of a polarization grating in FIG.

[0032] Figure 3 is the intensity variation diagram of the X component of the outgoing light;

[0033] Figure 4 A schematic diagram of the structure of a laser power stabilizer provided in an embodiment of the present application;

[0034] Figure 5 A step flow chart of the polarization modulation method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of this application, it should be noted that the terms "upper", "lower", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0039] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0040] It should be noted that, in the absence of conflict, different features in the embodiments of the present application may be combined with each other.

[0041] To solve the problems in the prior art, please refer to Figure 1 An embodiment of the present application provides a polarization modulation component 100, which includes a polarization grating 110, a lens 120, a phase delay wave plate 130 and a reflector 140 arranged in sequence.

[0042] The polarization grating 110 is used to split the incident linearly polarized light into left-handed polarized light (LCP) and right-handed polarized light (RCP). The left-handed polarized light and the right-handed polarized light are incident on the reflector 140 after passing through the lens 120 and the phase delay wave plate 130 in sequence, wherein the phase delay wave plate 130 is used to adjust the polarization state of the light. Exemplarily, the phase delay wave plate 130 includes a quarter wave plate (i.e., λ / 4 wave plate).

[0043] Specifically, if the incident light is linearly polarized light with the light vector along the X-axis, the expression can be:

[0044]

[0045] The incident linearly polarized light is split by the polarization grating 110 to obtain left-handed polarized light and right-handed polarized light, which can be written as and Here, ξ represents the phase distribution of the diffraction grating.

[0046] When the phase retardation wave plate 130 is a quarter wave plate, the incident light (including left-handed polarized light and right-handed polarized light) after passing through the phase retardation wave plate 130 can be expressed as:

[0047]

[0048] The reflector 140 is used to reflect left-handed polarized light and right-handed polarized light. The reflected left-handed polarized light and right-handed polarized light are incident on the lens 120 after passing through the phase delay wave plate 130 in sequence. The lens 120 is used to focus the reflected left-handed polarized light and right-handed polarized light. In addition, the polarization grating 110 can also be used to combine the focused reflected left-handed polarized light and right-handed polarized light to obtain modulated output light.

[0049] Specifically, the expression of the outgoing light after passing through the reflector 140 (ie, the left-handed polarized light and the right-handed polarized light after reflection) can be written as:

[0050]

[0051] The expression of the outgoing light after passing through the quarter-wave plate again can be:

[0052]

[0053] Finally, the expression of the outgoing light after passing through the polarization grating 110 is:

[0054]

[0055] At this time, the output light field after the left-handed polarized light and the right-handed polarized light are combined can be recorded as:

[0056]

[0057] It is not difficult to see from the above content that the polarization grating 110 and the reflector 140 are respectively located on opposite sides of the lens 120, and the phase delay wave plate 130 is located between the lens 120 and the reflector 140. Specifically, the polarization grating 110 and the reflector 140 are respectively located at the front and rear focal planes of the lens 120, that is, the distance l1 between the polarization grating 110 and the lens 120 can be equal to the focal length F of the lens 120, and the distance l2 between the reflector 140 and the lens 120 can be equal to the focal length F of the lens 120.

[0058] For further information, please refer to Figure 2 , the plane where the polarization grating 110 is located includes a first direction and a second direction perpendicular to each other, that is, Figure 2 In the x-axis direction and the y-axis direction, the second direction (i.e., the y-axis direction) is the same as the grating extension direction in the polarization grating 110. When the polarization grating 110 moves along the first direction (i.e., the x-axis direction), the intensity of the outgoing light changes periodically with the relative displacement of the polarization grating 110. Specifically, if the relative displacement of the polarization grating 110 in the first direction is Δx, the intensity of the X component in the outgoing light is:

[0059] I x (Δx) = cos 2 2ξ(x in +Δx),

[0060] That is, I x (Δx) = cos 2 4π(x in +Δx) / p,

[0061] It is not difficult to see from the above equation that the intensity of the X component of the outgoing light changes periodically with the relative displacement of the polarization grating 110, wherein when the phase delay wave plate 130 is a quarter wave plate, its change period is p / 4. Figure 3 , Figure 3 When the period P = 0.5 (5 μm), the intensity variation diagram of the X component of the emitted light is as follows: Figure 3 As shown, if the polarization grating 110 is relatively displaced by 1 (ie, 10 μm) in the first direction, the intensity of the X component of the outgoing light changes periodically 8 times.

[0062] In the above structure, the modulation process of the polarization modulation component 100 on the incident linear polarized light can refer to the following content: the incident linear polarized light is split into left-handed polarized light and right-handed polarized light by the polarization grating 110, and the left-handed polarized light and the right-handed polarized light are incident on the reflector 140 after passing through the lens 120 and the phase delay wave plate 130 in turn, and the left-handed polarized light and the right-handed polarized light are reflected to the polarization grating 110 via the reflector 140, and the polarization grating 110 combines the left-handed polarized light and the right-handed polarized light after the focused reflection to obtain the modulated polarized light. In the above process, if the displacement of the polarization grating 110 in the above X-axis direction is 0, the polarization state of the outgoing polarized light is the same as the polarization state of the incident linear polarized light.

[0063] In this embodiment, the polarization modulation component 100 includes a polarization grating 110, a lens 120, a phase delay wave plate 130 and a reflector 140 arranged in sequence. The polarization grating 110 can split the incident linear polarized light into left-handed polarized light and right-handed polarized light. The left-handed polarized light and the right-handed polarized light are incident on the reflector 140 after passing through the lens 120 and the phase delay wave plate 130 in sequence. The left-handed polarized light and the right-handed polarized light are reflected to the polarization grating 110 via the reflector 140. The polarization grating 110 combines the left-handed polarized light and the right-handed polarized light after the focused reflection to obtain the modulated polarized light. The polarization grating 110 not only has a fast response speed, but also can accurately control the polarization state of the light to achieve modulation of the laser. In addition, the polarization modulation component 100 provided in the embodiment of the present application has a simple structure and is suitable for a variety of scenarios that require rapid adjustment of the laser power.

[0064] Based on the same inventive concept, please refer to Figure 4 The present application also provides a laser power stabilizer 200, which includes a first light splitting component 210, a second light splitting component 220, a detection component 230, a control component 240 and the polarization modulation component 100 in the above embodiment.

[0065] The polarization modulation component 100 is connected to the first splitter component 210 and the control component respectively, wherein the laser output by the laser can be used as the input laser of the polarization strip paper component, and the polarization modulation component 100 can modulate the polarization direction of the input laser.

[0066] The first beam splitter component 210 is used to split the output beam of the polarization modulation component 100 to obtain a first polarized laser as a main loop beam and a second polarized laser as a branched beam. Specifically, the first beam splitter component 210 includes a polarization beam splitter 211, and the first polarized laser and the second polarized laser obtained by the polarization beam splitter 211 are linearly polarized light, and the polarization directions of the first polarized laser and the second polarized laser are perpendicular to each other, wherein the polarization beam splitter 211 can be a polarization beam splitter (PBS). In addition, the first beam splitter component 210 also includes a half wave plate 212, which can cooperate with the polarization beam splitter 211 to jointly achieve a variable splitting ratio.

[0067] Exemplarily, if the first polarized laser light is P light, the second polarized laser light is S light; if the first polarized laser light is S light, the second polarized laser light is P light. Assuming that the first polarized laser light is P light, the power of P light satisfies the following relationship:

[0068] P=P 0 *cos 2 θ,

[0069] Where, P is the power of the first polarized laser, P 0 is the power of the input laser, θ is the polarization angle of the laser output from the polarization adjustment component, and θ satisfies the following relationship:

[0070] θ∝Δx,

[0071] Wherein, Δx is the relative displacement of the polarization grating 110 in the polarization modulation component 100 in the first direction.

[0072] The second beam splitter 220 is used to split the first polarized laser to obtain a branched beam. Specifically, the second beam splitter 220 includes a beam splitter mirror, a beam splitter prism and / or a reflector 140 arranged in sequence in the light incident direction. The second beam splitter 220 is used to split the first polarized laser to obtain a transmitted beam and a reflected beam, and the beam with a smaller light intensity in the transmitted beam and the reflected beam is used as a split beam, and the beam with a larger light intensity in the transmitted beam and the reflected beam can be used as the output of the laser power stabilizer 200.

[0073] The detection component 230 is connected to the second light splitting component 220 and is used to detect the light intensity of the branched light beam and send the detection result to the control component 240 .

[0074] The control component 240 is connected to the detection component 230 to form a main loop, which is used to receive the detection result of the detection component 230 and adjust the polarization modulation component according to the detection result to adjust the light intensity of the first polarized laser to the target light intensity. Exemplarily, the control component 240 may include a PID controller and a piezoelectric driver. Specifically, the plane where the polarization grating 110 in the polarization modulation component 100 is located includes a first direction and a second direction that are perpendicular to each other, wherein the second direction is the same as the grating extension direction in the polarization grating 110. The control component 240 is used to control the polarization grating 110 to move linearly along the first direction according to the detection result, and the light intensity of the first polarized laser changes periodically with the displacement of the polarization grating 110.

[0075] In this embodiment, the laser power stabilizer 200 includes a first beam splitter component 210, a second beam splitter component 220, a detection component 230, a control component 240 and the polarization modulation component 100 in the above embodiment. After the polarization modulation component 100 modulates the polarization direction of the input laser, the first beam splitter component 210 and the second beam splitter component 220 system cooperate to obtain a beam splitter and an output beam of the laser power stabilizer 200. The beam splitter can be used as a feedback beam. The detection component 230 and the control component 240 control the polarization modulation component 100 based on the beam splitter, thereby realizing closed-loop control of the laser power. In the above structure, the polarization modulation component 100 has a simple structure and a fast response speed, and can realize the modulation of the laser. At the same time, when assembling the laser power stabilizer 200, the device volume of the laser power stabilizer 200 can be effectively controlled, making it suitable for a variety of scenarios that require rapid adjustment of the laser power.

[0076] In addition, please refer to Figure 5 The present application also provides a polarization modulation method. The order of some steps in the polarization modulation method in the embodiment of the present application can be interchanged according to actual needs, or some steps can be omitted or deleted. The detailed steps of the polarization modulation method are introduced as follows.

[0077] Step S110: Splitting the incident linearly polarized light into left-handed polarized light and right-handed polarized light via a polarization grating.

[0078] In this step, the polarization grating 110 is used to split the incident linearly polarized light (ie, incident light) into left-handed polarized light and right-handed polarized light, wherein, if the incident light is linearly polarized light with the light vector along the X-axis, the expression thereof can be:

[0079]

[0080] The incident linearly polarized light is split by the polarization grating 110 to obtain left-handed polarized light and right-handed polarized light, which can be written as and Here, ξ represents the phase distribution of the diffraction grating.

[0081] Step S120: before the left-handed polarized light and the right-handed polarized light return to the polarization grating via the lens, the phase delay wave plate and the reflector in sequence, the polarization direction of the incident linear polarized light is modulated by the polarization grating to achieve the target output light intensity.

[0082] In this step, when the phase delay wave plate 130 is a quarter wave plate, the incident light (including left-handed polarized light and right-handed polarized light) after passing through the phase delay wave plate 130 can be expressed as:

[0083]

[0084] The expression of the outgoing light after passing through the reflector 140 (i.e., the left-handed polarized light and the right-handed polarized light after reflection) can be written as:

[0085]

[0086] The expression of the outgoing light after passing through the quarter-wave plate again can be:

[0087]

[0088] Finally, the expression of the outgoing light after passing through the polarization grating 110 is:

[0089]

[0090] At this time, the output light field after the left-handed polarized light and the right-handed polarized light are combined can be recorded as:

[0091]

[0092] The plane where the polarization grating 110 in the polarization modulation component 100 is located includes a first direction and a second direction that are perpendicular to each other, wherein the second direction is the same as the grating extension direction in the polarization grating 110 .

[0093] After the left-handed polarized light and the right-handed polarized light successively pass through the lens 120, the phase delay wave plate 130 and the reflector 140 and then return to the polarization grating 110, the polarization grating 110 is moved along the first direction according to the intensity of the target output light, and the intensity of the output light changes periodically with the displacement of the polarization grating 110, wherein the target grating direction is perpendicular to the grating direction.

[0094] Specifically, the relative displacement of the polarization grating 110 in the first direction can be Δx, and the intensity of the X component in the outgoing light is:

[0095] I x (Δx) = cos 2 2ξ(xin +Δx),

[0096] I x (Δx) = cos 2 4π(x in +Δx) / p,

[0097] That is, the intensity of the X component of the outgoing light changes periodically with the relative displacement of the polarization grating 110, and its change period is p / 4. In this way, the polarization grating 110 can be moved along the first direction according to the intensity of the target outgoing light until the intensity of the outgoing light of the polarization grating reaches the intensity of the target outgoing light.

[0098] In this embodiment, the incident linear polarized light is split into left-handed polarized light and right-handed polarized light by the polarization grating 110, and then the left-handed polarized light and the right-handed polarized light are returned to the front of the polarization grating 110 through the lens 120, the phase delay wave plate 130 and the reflector 140 in sequence. Finally, the polarization direction of the incident linear polarized light is modulated by the polarization grating 110 to achieve the target output light intensity. The invention has the advantages of fast response speed, simple structure and low manufacturing cost.

[0099] In summary, the embodiments of the present application provide a polarization modulation component, a laser power stabilizer, and a polarization modulation method. The polarization modulation component includes a polarization grating, a lens, a phase delay wave plate, and a reflector arranged in sequence. The polarization grating can split the incident linear polarized light into left-handed polarized light and right-handed polarized light. The left-handed polarized light and the right-handed polarized light are incident on the reflector after passing through the lens and the phase delay wave plate in sequence. The left-handed polarized light and the right-handed polarized light are reflected to the polarization grating through the reflector. The polarization grating combines the left-handed polarized light and the right-handed polarized light after the focused reflection to obtain the modulated polarized light. The polarization grating not only has a fast response speed, but also can accurately control the polarization state of the light to achieve modulation of the laser. In addition, the polarization modulation component provided in the embodiments of the present application has a simple structure and is suitable for a variety of scenarios that require rapid adjustment of the laser power.

[0100] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A polarization modulation component, characterized in that: It includes a polarization grating, a lens, a phase delay wave plate and a reflector arranged in sequence; The polarization grating is used to split the incident linear polarized light into left-handed polarized light and right-handed polarized light, and the left-handed polarized light and the right-handed polarized light are incident on the reflector after passing through the lens and the phase delay wave plate in sequence, wherein the phase delay wave plate is used to adjust the polarization state of the light; The reflector is used to reflect the left-handed polarized light and the right-handed polarized light, and the reflected left-handed polarized light and the right-handed polarized light are incident on the lens after passing through the phase delay wave plate in sequence, and the lens is used to focus the reflected left-handed polarized light and the right-handed polarized light; The polarization grating is also used to combine the left-handed polarized light and the right-handed polarized light after focus reflection to obtain modulated output light.

2. The polarization modulation assembly according to claim 1, characterized in that: The polarization grating and the reflector are respectively located on opposite sides of the lens, the distance between the polarization grating and the lens is equal to the focal length of the lens, and the distance between the reflector and the lens is equal to the focal length of the lens.

3. The polarization modulation assembly according to claim 1, characterized in that: The plane where the polarization grating is located includes a first direction and a second direction that are perpendicular to each other; The polarization grating extends along the first direction. When the polarization grating moves along the second direction, the light intensity of the emergent light changes periodically with the relative displacement of the polarization grating.

4. The polarization modulation assembly according to claim 1, characterized in that: The phase retardation wave plate comprises a quarter wave plate.

5. A laser power stabilizer, characterized in that: It comprises a first light splitting component, a second light splitting component, a detection component, a control component and a polarization modulation component as described in any one of claims 1 to 4; The polarization modulation component is connected to the first light splitting component and the control component respectively, and is used to modulate the polarization direction of the input laser; The first beam splitter is used to split the output beam of the polarization modulation component to obtain a first polarized laser beam as a main loop beam and a second polarized laser beam as a branched beam; The second light splitting component is used to split the first polarized laser to obtain a branch light beam; The detection component is connected to the second light splitting component, and is used to detect the light intensity of the branch light beam and send the detection result to the control component; The control component is connected to the detection component to form a main loop for receiving the detection result of the detection component and adjusting the polarization modulation component according to the detection result to adjust the light intensity of the first polarized laser to the target light intensity.

6. The laser power stabilizer according to claim 5, characterized in that: The first beam splitting component includes a polarization beam splitter. The first polarized laser light and the second polarized laser light split by the polarization beam splitter are linearly polarized light, and polarization directions of the first polarized laser light and the second polarized laser light are perpendicular to each other.

7. The laser power stabilizer according to claim 5, characterized in that: The second beam splitter component includes a beam splitter mirror, a beam splitter prism and / or a reflector arranged in sequence in the light incident direction. The second beam splitter component is used to split the first polarized laser to obtain a transmitted beam and a reflected beam, and use the beam with smaller light intensity between the transmitted beam and the reflected beam as the split beam.

8. The laser power stabilizer according to claim 5, characterized in that: The plane where the polarization grating in the polarization modulation component is located includes a first direction and a second direction perpendicular to each other, wherein the second direction is the same as the grating extension direction in the polarization grating; The control component is used to control the polarization grating to move linearly along the first direction according to the detection result, and the light intensity of the first polarized laser changes periodically with the displacement of the polarization grating.

9. A polarization modulation method, characterized in that: The polarization modulation component as claimed in any one of claims 1 to 4, wherein the method comprises: Splitting incident linearly polarized light into left-handed polarized light and right-handed polarized light via the polarization grating; Before the left-handed polarized light and the right-handed polarized light return to the polarization grating via the lens, the phase delay wave plate and the reflector in sequence, the polarization direction of the incident linear polarized light is modulated by the polarization grating to achieve the target output light intensity.

10. The polarization modulation method according to claim 9, characterized in that: The plane where the polarization grating in the polarization modulation component is located includes a first direction and a second direction perpendicular to each other, wherein the second direction is the same as the extension direction of the grating in the polarization grating, and the step of modulating the polarization direction of the incident linear polarized light through the polarization grating before the left-handed polarized light and the right-handed polarized light return to the polarization grating along the original path after passing through the lens, the phase delay wave plate and the reflector in sequence to achieve the target light intensity of the output light includes: Before the left-handed polarized light and the right-handed polarized light return to the polarization grating along the original path after passing through the lens, the phase delay wave plate and the reflector in sequence, the polarization grating is moved along the first direction according to the intensity of the target output light, and the intensity of the target output light changes periodically with the displacement of the polarization grating.

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