Holographic exposure system and method for preparing grating
By using single-mode fiber to propagate the beam in grating preparation, the spatial frequency filtering of the beam is achieved, which solves the problem of low grating pattern clarity and improves the resolution and quality of the grating.
Patent Information
- Application Number
- CN202411879805.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-03-28
AI Technical Summary
In the prior art, it is difficult to effectively ensure the clarity of the grating pattern when preparing the grating, mainly because the adjustment of the beam focus position and pinhole size is difficult, resulting in blurring and distortion of the grating pattern.
Single-mode optical fiber is used to propagate the beam, and single-mode optical fiber is used to selectively use the spatial frequency to realize spatial frequency filtering of the beam, avoiding cumbersome adjustment of the beam focus position and pinhole size.
The spatial frequency filtering of the beam is achieved through single-mode optical fiber, which effectively improves the clarity of the grating pattern, ensures the resolution, measurement accuracy and diffraction efficiency of the prepared grating, and improves the quality of the grating.
Smart Images
Figure CN119717100A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of optical devices, and in particular to a holographic exposure system and method for preparing a grating. Background Art
[0002] At present, gratings can be prepared by holographic exposure methods, and the commonly used holographic exposure method for making gratings is a double-beam interference method, that is, a beam of light is divided into two beams of equal power through a beam splitter. The two beams interfere with each other to form a grating pattern on the surface of the substrate, thereby preparing a grating. In order to reduce the blur and distortion of the grating pattern and improve the clarity of the grating pattern, it is necessary to filter the light beam to filter out the additional spatial frequency components in the light beam. The related technology mainly uses a pinhole filter to filter the light beam. The pinhole filter consists of a focusing lens and a micron-scale pinhole. The light beam is focused at the pinhole. By controlling the size of the pinhole, the required spatial frequency passes through, and the unnecessary frequency will be filtered out by the pinhole. However, in order to achieve a good filtering effect, it is necessary to adjust the position of the light beam focus to be at the pinhole, and control the size of the pinhole to match the required spatial frequency. The adjustment is difficult and the clarity of the grating pattern cannot be effectively guaranteed. Summary of the invention
[0003] The embodiments of the present invention provide a holographic exposure system and method for preparing a grating, aiming to improve the clarity of the grating pattern.
[0004] In a first aspect, an embodiment of the present invention provides a holographic exposure system for preparing a grating, comprising:
[0005] An optical transmitter for emitting an optical beam; a single-mode optical fiber for filtering the optical beam and transmitting the filtered optical beam to an optical fiber beam splitter; the optical fiber beam splitter is used to split the filtered optical beam into a first optical beam and a second optical beam, and transmit the first optical beam to a first polarization beam splitter through the single-mode optical fiber and transmit the second optical beam to a second polarization beam splitter through the single-mode optical fiber; the first polarization beam splitter is used to polarize the first optical beam into a first polarization optical beam, and emit the first polarization optical beam to a first beam expander through the single-mode optical fiber; the second polarization beam splitter is used to polarize the second optical beam into a second polarization optical beam, and transmit the first polarization optical beam to a second beam expander through the single-mode optical fiber. The polarized light beam is emitted to the second beam expander, and the polarization of the first polarized light beam is consistent with that of the second polarized light beam; the first beam expander is used to expand the first polarized light beam to obtain a first interference light beam and propagate the first interference light beam to the first plane reflector; the second beam expander is used to expand the second polarized light beam to obtain a second interference light beam and propagate the second interference light beam to the second plane reflector; the first plane reflector is used to reflect the first interference light beam to an interference area, and the second plane reflector is used to reflect the second interference light beam to the interference area, so as to form a grating pattern on the substrate surface in the interference area.
[0006] In a possible implementation, the first beam expander includes a first off-axis parabolic reflector, the first polarized light beam emitted through the single-mode optical fiber is at a focal position of the first off-axis parabolic reflector, and the first off-axis parabolic reflector is used to expand the first polarized light beam into a parallel first interference light beam and reflect it to the first plane reflector;
[0007] The second beam expander includes a second off-axis parabolic reflector. The second polarized light beam emitted through the single-mode optical fiber is located at the focal position of the second off-axis parabolic reflector. The second off-axis parabolic reflector is used to expand the second polarized light beam into a parallel second interference light beam and reflect it to the second plane reflector.
[0008] In a possible implementation, a focal length of the first off-axis parabolic reflector is the same as a focal length of the second off-axis parabolic reflector, and a size of the first off-axis parabolic reflector is the same as a size of the second off-axis parabolic reflector.
[0009] In a possible implementation, the first beam expander includes a first lens, the first polarized light beam emitted through the single-mode optical fiber is at a focal position of the first lens, and the first lens is used to expand the first polarized light beam into a parallel first interference light beam and transmit it to the first plane reflector;
[0010] The second beam expander includes a second lens, and the second polarized light beam emitted through the single-mode optical fiber is at the focal position of the second lens. The second lens is used to expand the second polarized light beam into a parallel second interference light beam and transmit it to the second plane reflector.
[0011] In a possible implementation, the focal length of the first lens is the same as the focal length of the second lens, and the size of the first lens is the same as the size of the second lens.
[0012] In a possible implementation, the holographic exposure system further includes:
[0013] A first optical fiber polarization controller, disposed between the optical fiber beam splitter and the first polarization beam splitter, for adjusting the polarization of the first light beam to cooperate with the first polarization beam splitter to adjust the optical power of the first light beam;
[0014] A second optical fiber polarization controller, disposed between the optical fiber beam splitter and the second polarization beam splitter, for adjusting the polarization of the first light beam to cooperate with the second polarization beam splitter to adjust the optical power of the second light beam;
[0015] The optical power of the first polarized light beam is consistent with that of the second polarized light beam.
[0016] In a possible implementation manner, polarization control parameters of the first optical fiber polarization controller and the second optical fiber polarization controller are the same.
[0017] In a possible implementation, the optical transmitter includes a fiber laser, and the fiber laser is connected to the single-mode optical fiber so that the light beam emitted by the fiber laser propagates along the single-mode optical fiber.
[0018] In a possible implementation, the light emitter includes a spatial laser, and the holographic exposure system further includes:
[0019] A coupler is used to couple the light beam emitted by the spatial laser to the end face of the single-mode optical fiber, so that the light beam propagates along the single-mode optical fiber.
[0020] In a second aspect, an embodiment of the present invention further provides a holographic exposure method for preparing a grating, comprising:
[0021] filtering the light beam emitted by the light transmitter through the single-mode optical fiber and transmitting the filtered light beam to the optical fiber beam splitter;
[0022] Splitting the filtered light beam into a first light beam and a second light beam by the optical fiber beam splitter;
[0023] transmitting the first light beam to the first polarization beam splitter through the single-mode optical fiber and transmitting the second light beam to the second polarization beam splitter through the single-mode optical fiber;
[0024] Polarizing the first light beam into a first polarized light beam through the first polarization beam splitter, and emitting the first polarized light beam to a first beam expander through the single-mode optical fiber;
[0025] Polarizing the second light beam into a second polarized light beam through the second polarization beam splitter, and emitting the first polarized light beam to a second beam expander through the single-mode optical fiber, wherein the polarization of the first polarized light beam is consistent with that of the second polarized light beam;
[0026] Expanding the first polarized light beam by the first beam expander to obtain a first interference light beam and transmitting the first interference light beam to the first plane reflector;
[0027] Expanding the second polarized light beam by the second beam expander to obtain a second interference light beam and propagating the second interference light beam to the second plane reflector;
[0028] The first plane reflecting mirror is used to reflect the first interference light beam to an interference region, and the second plane reflecting mirror is used to reflect the second interference light beam to the interference region, so as to form a grating pattern on the surface of the substrate in the interference region.
[0029] The technical solution provided by the embodiment of the present invention uses a single-mode optical fiber to propagate a light beam. Since the single-mode optical fiber is selective to the spatial frequency, light of additional spatial frequencies will not be able to enter the single-mode optical fiber. Therefore, the spatial frequency filtering of the light beam can be achieved by propagating the light beam in the single-mode optical fiber. There is no need to tediously adjust the position of the light beam focus and the size of the pinhole. The implementation process is simple and effective, and the clarity of the grating pattern is effectively guaranteed to ensure the resolution, measurement accuracy and diffraction efficiency of the prepared grating, thereby improving the quality of the prepared grating. In addition, a large-area grating pattern can be formed by interference through an optical fiber beam splitter, a first polarization beam splitter, a second polarization beam splitter, a first beam expander, a second beam expander, a first plane reflector and a second plane reflector. Therefore, the resolution, measurement accuracy and diffraction efficiency of the prepared large-area grating can be effectively guaranteed, thereby improving the quality of the prepared large-area grating. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0031] Figure 1 is a schematic diagram of a holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0032] Figure 2 is a schematic diagram of another holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0033] Figure 3 is a schematic diagram of another holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0034] Figure 4 is a schematic diagram of another holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0035] Figure 5 is a schematic diagram of another holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0036] Figure 6 is a schematic diagram of another holographic exposure system for preparing a grating provided by an embodiment of the present invention;
[0037] Figure 7 It is a schematic diagram of a holographic exposure method for preparing a grating provided in an embodiment of the present invention.
[0038] Figure numerals: 100, holographic exposure system; 11, light transmitter; 12, single-mode optical fiber; 13, optical fiber beam splitter; 21, first polarization beam splitter; 22, first beam expander; 221, first off-axis parabolic mirror; 222, first lens; 23, first plane mirror; 24, first optical fiber polarization controller; 31, second polarization beam splitter; 32, second beam expander; 321, second off-axis parabolic mirror; 322, second lens; 33, second plane mirror; 34, second optical fiber polarization controller; 14, substrate; 15, coupler. DETAILED DESCRIPTION
[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0040] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.
[0041] It should be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.
[0042] At present, gratings can be prepared by holographic exposure methods, and the commonly used holographic exposure method for making gratings is a double-beam interference method, that is, a beam of light is divided into two beams of equal power through a beam splitter. The two beams interfere with each other to form a grating pattern on the surface of the substrate, thereby preparing a grating. In order to reduce the blur and distortion of the grating pattern and improve the clarity of the grating pattern, it is necessary to filter the light beam to filter out the additional spatial frequency components in the light beam. The related technology mainly uses a pinhole filter to filter the light beam. The pinhole filter consists of a focusing lens and a micron-scale pinhole. The light beam is focused at the pinhole. By controlling the size of the pinhole, the required spatial frequency passes through, and the unnecessary frequency will be filtered out by the pinhole. However, in order to achieve a good filtering effect, it is necessary to adjust the position of the light beam focus to be at the pinhole, and control the size of the pinhole to match the required spatial frequency. The adjustment is difficult and the clarity of the grating pattern cannot be effectively guaranteed.
[0043] The embodiment of the present invention uses a single-mode optical fiber to propagate a light beam. Since the single-mode optical fiber is selective to the spatial frequency, light of additional spatial frequencies will not be able to enter the single-mode optical fiber. Therefore, the spatial frequency filtering of the light beam can be achieved by propagating the light beam in the single-mode optical fiber. There is no need to tediously adjust the position of the light beam focus and the size of the pinhole. The implementation process is simple and effective, and the clarity of the grating pattern is effectively guaranteed to ensure the resolution, measurement accuracy and diffraction efficiency of the prepared grating, thereby improving the quality of the prepared grating. In addition, a large-area grating pattern can be formed by interference through an optical fiber beam splitter, a first polarization beam splitter, a second polarization beam splitter, a first beam expander, a second beam expander, a first plane reflector and a second plane reflector. Therefore, the resolution, measurement accuracy and diffraction efficiency of the prepared large-area grating can be effectively guaranteed, thereby improving the quality of the prepared large-area grating.
[0044] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0045] See also Figure 1The holographic exposure system 100 includes: a light transmitter 11, a single-mode optical fiber 12, a fiber beam splitter 13, a first polarization beam splitter 21, a first beam expander 22, a first plane reflector 23, a second polarization beam splitter 31, a second beam expander 32, a second plane reflector 33 and a substrate 14. The light transmitter 11 is fixedly connected or coupled to the single-mode optical fiber 12, the fiber beam splitter 13 is connected to the first polarization beam splitter 21 through a single-mode optical fiber, and the fiber beam splitter 13 is connected to the second polarization beam splitter 31 through a single-mode optical fiber.
[0046] The optical transmitter 11 is used to emit a light beam; the single-mode optical fiber 12 is used to filter the light beam and transmit the filtered light beam to the optical fiber beam splitter; the optical fiber beam splitter 13 is used to split the filtered light beam into a first light beam and a second light beam, and transmit the first light beam to the first polarization beam splitter 21 through the single-mode optical fiber and transmit the second light beam to the second polarization beam splitter 31 through the single-mode optical fiber; the first polarization beam splitter 21 is used to polarize the first light beam into a first polarized light beam, and emit the first polarized light beam to the first beam expander 22 through the single-mode optical fiber; the second polarization beam splitter 31 is used to polarize the second light beam into a second polarized light beam, and transmit the second light beam to the second beam through the single-mode optical fiber. The first polarized light beam is emitted to the second beam expander 32, and the polarization of the first polarized light beam is consistent with that of the second polarized light beam; the first beam expander 22 is used to expand the first polarized light beam to obtain a first interference light beam and transmit the first interference light beam to the first plane mirror 23; the second beam expander 32 is used to expand the second polarized light beam to obtain a second interference light beam and transmit the second interference light beam to the second plane mirror 33; the first plane mirror 23 is used to reflect the first interference light beam to the interference area, and the second plane mirror 33 is used to reflect the second interference light beam to the interference area to form a grating pattern on the surface of the substrate 14 in the interference area.
[0047] The embodiment of the present invention uses a single-mode optical fiber to propagate a light beam. Since the single-mode optical fiber is selective for spatial frequency, light with additional spatial frequencies will not be able to enter the single-mode optical fiber. Therefore, spatial frequency filtering of the light beam can be achieved by propagating the light beam in the single-mode optical fiber. There is no need to tediously adjust the position of the light beam focus and the size of the pinhole. The implementation process is simple and effective, and the clarity of the grating pattern is effectively guaranteed to ensure the resolution, measurement accuracy and diffraction efficiency of the prepared grating, thereby improving the quality of the prepared grating. In addition, a large-area grating pattern can be formed by interference through the optical fiber beam splitter 13, the first polarization beam splitter 21, the first beam expander 22, the first plane reflector 23, the second polarization beam splitter 31, the second beam expander 32 and the second plane reflector 33. Therefore, the resolution, measurement accuracy and diffraction efficiency of the prepared large-area grating can be effectively guaranteed, thereby improving the quality of the prepared large-area grating. In addition, the use of a single-mode optical fiber to propagate the light beam can reduce light loss and ensure the light intensity of the light beam required for preparing the grating.
[0048] It should be noted that a large-area grating refers to a grating with a diameter greater than or equal to 5 cm, or a large-area grating refers to a grating with a diameter greater than or equal to 10 cm. The angle between the first interference light beam reflected to the interference area by the first plane reflector 23 and the second interference light beam reflected to the interference area by the second plane reflector 33 is the interference angle. The interference angle can affect the density of the interference fringes, that is, the period of the manufactured grating. According to the grating equation, the grating period and the interference angle can satisfy the formula: d = λ / (sinθ 1 +sinθ 2 ), where d is the grating period, λ is the exposure wavelength, and θ 1 is the angle between the first interference light beam reflected by the first plane reflector 23 to the surface of the substrate 14 and the normal vector of the surface of the substrate 14, θ 2 is the angle between the second interference light beam reflected by the second plane reflector 33 to the surface of the substrate 14 and the normal vector of the surface of the substrate 14, θ 1 With θ 2 Can be equal or unequal, θ 1 is related to the angle of the first plane reflector 23, and θ 2 The angle of the second plane reflector 33 is related to that of the first plane reflector 23 and / or the second plane reflector 33. Therefore, the grating period can be changed by adjusting the angle of the first plane reflector 23 and / or the second plane reflector 33. That is to say, the holographic exposure system 100 provided by the embodiment of the present invention can prepare gratings of various periods as required, such as preparing gratings of any period from 100 nanometers to 99 micrometers, such as preparing gratings of any period from 300 nanometers to 85 micrometers, etc.
[0049] In some embodiments, the optical fiber beam splitter 13 is used to split the filtered light beam into a first light beam and a second light beam with equal optical power. The optical fiber beam splitter 13 may include an optical fiber splitter. The first polarization beam splitter 21 is used to split the first light beam into a first polarized light beam and a third polarized light beam, the vibration direction of the first polarized light beam is perpendicular to the incident plane, and the vibration direction of the third polarized light beam is parallel to the incident plane, so that the first polarized light beam propagates along a single-mode optical fiber to the first beam expander 22, and the third polarized light beam propagates along another single-mode optical fiber to the outside of the space, and will not propagate to the first beam expander 22. The second polarization beam splitter 31 is used to split the second light beam into a second polarized light beam and a fourth polarized light beam, the vibration direction of the second polarized light beam is perpendicular to the incident plane, and the vibration direction of the fourth polarized light beam is parallel to the incident plane, so that the second polarized light beam propagates along a single-mode optical fiber to the second beam expander 32, and the fourth polarized light beam propagates along another single-mode optical fiber to the outside of the space, and will not propagate to the second beam expander 32.
[0050] In some embodiments, the first polarization beam splitter 21 and the second polarization beam splitter 31 have the same property parameters. The property parameters include at least one of the central wavelength, bandwidth range, and splitting ratio of the first polarization beam splitter 21 and the second polarization beam splitter 31. In the embodiment of the present invention, since the property parameters of the first polarization beam splitter 21 and the second polarization beam splitter 31 are the same, the polarization directions of the first polarization beam obtained by polarization of the first polarization beam splitter 21 and the second polarization beam obtained by polarization of the second polarization beam splitter 31 can be consistent, so as to ensure the contrast of the interference pattern (grating pattern).
[0051] It should be noted that a suitable light source can be selected for exposure according to actual needs, such as an ultraviolet light source, a deep ultraviolet light source, etc., as long as the photoresist material can record the wavelength of the light source, such as the wavelength of visible light, for example, the wavelength of the light source is any wavelength in the range of 350nm-780nm, and the wavelength of the light source can also be a laser wavelength, for example, the wavelength of the light source is 1064nm, 1550nm, 980nm, 808nm or 532nm. The following is an example of a laser light source.
[0052] In some embodiments, the optical transmitter 11 comprises a fiber laser, such as Figure 1 As shown, the fiber laser (light transmitter 11) is connected to the single-mode optical fiber 12 so that the light beam emitted by the fiber laser (light transmitter 11) propagates along the single-mode optical fiber 12. The wavelength of the light beam emitted by the fiber laser (light transmitter 11) is within the operating wavelength range of the single-mode optical fiber 12, and the operating wavelength range of the single-mode optical fiber 12 can be 300nm to 1650nm. The embodiment of the present invention uses a fiber laser as a light transmitter and is fixedly connected to the optical fiber, so that the emitted light beam can propagate along the single-mode optical fiber 12 without the need for additional devices, thereby reducing costs.
[0053] In some embodiments, the optical transmitter 11 comprises a spatial laser, such as Figure 2 and 4 As shown, the holographic exposure system 100 further includes: a coupler 15, which is used to couple the light beam emitted by the space laser (light transmitter 11) to the end face of the single-mode optical fiber 12, so that the light beam emitted by the space laser (light transmitter 11) propagates along the single-mode optical fiber 12. The coupler 15 may include a lens. The embodiment of the present invention uses a space laser as a light transmitter coupled with an optical fiber, which facilitates replacement of the light transmitter after damage.
[0054] In some embodiments, Figure 3 and 4As shown, the first beam expander 22 includes a first off-axis parabolic reflector 221, and the first polarized light beam emitted through the single-mode optical fiber is at the focus of the first off-axis parabolic reflector 221. The first off-axis parabolic reflector 221 is used to expand the first polarized light beam into a parallel first interference light beam and reflect it to the first plane reflector 23; the second beam expander 32 includes a second off-axis parabolic reflector 321, and the second polarized light beam emitted through the single-mode optical fiber is at the focus of the second off-axis parabolic reflector 321. The second off-axis parabolic reflector 321 is used to expand the second polarized light beam into a parallel second interference light beam and reflect it to the second plane reflector 33. Wherein, Figure 3 The optical transmitter 11 is a fiber laser. Figure 4 The optical transmitter 11 is a space laser.
[0055] The embodiment of the present invention uses an off-axis parabolic reflector to achieve beam expansion. Since the light emitted from the focus of the off-axis parabolic reflector is parallel light after being reflected by the off-axis parabolic reflector, there is no spherical aberration and chromatic aberration, thereby effectively improving the clarity of the interference pattern (grating pattern). In addition, a large-diameter off-axis parabolic reflector is easier to process than a large-diameter lens, and can more conveniently prepare a large-area grating, and can also ensure the clarity of the large-area grating.
[0056] In some embodiments, the focal length of the first off-axis parabolic reflector 221 is the same as or substantially the same as the focal length of the second off-axis parabolic reflector 321, and the size of the first off-axis parabolic reflector 221 is the same as or substantially the same as the size of the second off-axis parabolic reflector 321. In the embodiment of the present invention, since the focal length and size of the first off-axis parabolic reflector 221 are the same as the focal length and size of the second off-axis parabolic reflector 321, the consistency of the light beam emitted by the first off-axis parabolic reflector 221 and the light beam emitted by the second off-axis parabolic reflector 321 can be ensured, so that the stability of the grating pattern can be improved, the blur and distortion of the grating pattern can be reduced, and the uniformity of the grating can be ensured.
[0057] Among them, if the difference between the focal length of the first off-axis parabolic reflector 221 and the focal length of the second off-axis parabolic reflector 321 is less than or equal to the first threshold, it can be determined that the focal length of the first off-axis parabolic reflector 221 is approximately the same as the focal length of the second off-axis parabolic reflector 321, and if the difference between the size of the first off-axis parabolic reflector 221 and the size of the second off-axis parabolic reflector 321 is less than or equal to the second threshold, it can be determined that the size of the first off-axis parabolic reflector 221 is approximately the same as the size of the second off-axis parabolic reflector 321.
[0058] It should be noted that the first off-axis parabolic reflector 221 and the second off-axis parabolic reflector 321 with appropriate focal length and size can be selected according to the area required for the grating actually prepared. For example, to prepare a grating with a diameter of 10 cm, the first off-axis parabolic reflector 221 and the second off-axis parabolic reflector 321 with diameters of 10 cm and focal lengths of 500 mm or 1 m can be selected, so that a grating with a diameter of 10 cm can be prepared by the holographic exposure system in the embodiment of the present invention.
[0059] In some embodiments, Figure 5 As shown, the holographic exposure system 100 also includes: a first optical fiber polarization controller 24, which is arranged between the optical fiber beam splitter 13 and the first polarization beam splitter 21, and is used to adjust the polarization of the first light beam, so as to cooperate with the first polarization beam splitter 21 to adjust the optical power of the first light beam; a second optical fiber polarization controller 34, which is arranged between the optical fiber beam splitter 13 and the second polarization beam splitter 31, and is used to adjust the polarization of the first light beam, so as to cooperate with the second polarization beam splitter 31 to adjust the optical power of the second light beam, and the optical power of the first polarized light beam is consistent with that of the second polarized light beam. Among them, the optical fiber beam splitter 13, the first optical fiber polarization controller 24 and the first polarization beam splitter 21 are connected through a single-mode optical fiber, and the optical fiber beam splitter 13, the second optical fiber polarization controller 34 and the second polarization beam splitter 31 are connected through a single-mode optical fiber. The embodiment of the present invention can realize the optical power adjustment of the light beam through the optical fiber polarization controller and the polarization beam splitter, so as to ensure the consistency of the interference power of the two light beams, so as to ensure the depth and uniformity of the grating.
[0060] In some embodiments, the first optical fiber polarization controller 24 and the second optical fiber polarization controller 34 have the same property parameters. The property parameters include the type of optical fiber polarization controller and polarization control parameters. The type of optical fiber polarization controller may include three-ring type and squeeze type, that is, the optical fiber polarization controller may include a three-ring polarization controller or a squeeze polarization controller. The polarization control parameters of the three-ring polarization controller may include the relative angles between the three optical fiber coils (equivalent to three glass slides) contained in the three-ring polarization controller, and the relative angles between the three optical fiber coils may be adjusted by rotating the optical fiber coils. The polarization control parameters of the squeeze polarization controller may include the mechanical pressure output by the squeezer. In the embodiment of the present invention, since the property parameters of the first optical fiber polarization controller 24 and the second optical fiber polarization controller 34 are the same, and the property parameters of the first polarization beam splitter 21 and the second polarization beam splitter 31 are the same, the consistency of the dual-beam interference power can be guaranteed.
[0061] In some embodiments, Figure 6As shown, the first beam expander 22 includes a first lens 222, and the first polarized light beam emitted through the single-mode optical fiber is at the focal position of the first lens 222. The first lens is used to expand the first polarized light beam into a parallel first interference light beam and transmit it to the first plane reflector 23; the second beam expander 32 includes a second lens 322, and the second polarized light beam emitted through the single-mode optical fiber is at the focal position of the second lens 322. The second lens 322 is used to expand the second polarized light beam into a parallel second interference light beam and transmit it to the second plane reflector 33. The embodiment of the present invention uses a lens to achieve beam expansion. Since the light emitted from the focal point of the lens is parallel light after being transmitted through the lens, the spherical aberration and chromatic aberration are small, thereby effectively improving the clarity of the interference pattern (grating pattern).
[0062] In some embodiments, the focal length of the first lens 222 is the same or substantially the same as the focal length of the second lens 322, and the size of the first lens 222 is the same or substantially the same as the size of the second lens 322. In the embodiment of the present invention, since the focal length and size of the first lens 222 are the same as the focal length and size of the second lens 322, the consistency of the light beam transmitted through the first lens 222 and the light beam transmitted through the second lens 322 can be ensured, thereby improving the stability of the grating pattern, reducing the blur and distortion of the grating pattern, and ensuring the uniformity of the grating.
[0063] Among them, if the difference between the focal length of the first lens 222 and the focal length of the second lens 322 is less than or equal to the first threshold, it can be determined that the focal length of the first lens 222 is substantially the same as the focal length of the second lens 322, and if the difference between the size of the first lens 222 and the size of the second lens 322 is less than or equal to the second threshold, it can be determined that the size of the first lens 222 is substantially the same as the size of the second lens 322. It should be noted that the first lens 222 and the second lens 322 with appropriate focal lengths and sizes can be selected according to the area required by the grating actually prepared.
[0064] See also Figure 7 , Figure 7 It is a schematic diagram of a holographic exposure method for preparing a grating provided in an embodiment of the present invention.
[0065] like Figure 7 As shown, the method includes steps S101 to S108.
[0066] Step S101 : filtering a light beam emitted by an optical transmitter through a single-mode optical fiber and transmitting the filtered light beam to an optical fiber beam splitter.
[0067] Step S102: Split the filtered light beam into a first light beam and a second light beam through an optical fiber beam splitter.
[0068] Step S103 : transmitting the first light beam to the first polarization beam splitter through the single-mode optical fiber and transmitting the second light beam to the second polarization beam splitter through the single-mode optical fiber.
[0069] Step S104 , polarizing the first light beam into a first polarized light beam through a first polarization beam splitter, and emitting the first polarized light beam to a first beam expander through a single-mode optical fiber.
[0070] Step S105 , polarizing the second light beam into a second polarized light beam through a second polarization beam splitter, and emitting the first polarized light beam to a second beam expander through a single-mode optical fiber, wherein the polarizations of the first polarized light beam and the second polarized light beam are consistent.
[0071] Step S106: Expand the first polarized light beam through a first beam expander to obtain a first interference light beam and propagate the first interference light beam to a first plane reflector.
[0072] Step S107: Expand the second polarized light beam by a second beam expander to obtain a second interference light beam and propagate the second interference light beam to a second plane reflector.
[0073] Step S108, reflecting the first interference light beam to the interference region through the first plane reflection mirror, and reflecting the second interference light beam to the interference region through the second plane reflection mirror, so as to form a grating pattern on the surface of the substrate in the interference region.
[0074] The above method uses a single-mode optical fiber to propagate a light beam. Since the single-mode optical fiber is selective to the spatial frequency, light of additional spatial frequencies will not be able to enter the single-mode optical fiber. Therefore, the spatial frequency filtering of the light beam can be achieved by propagating the light beam in the single-mode optical fiber. There is no need to tediously adjust the position of the light beam focus and the size of the pinhole. The implementation process is simple and effective, and the clarity of the grating pattern is effectively guaranteed to ensure the resolution, measurement accuracy and diffraction efficiency of the prepared grating, thereby improving the quality of the prepared grating. In addition, a large-area grating pattern can be formed by interference through the optical fiber beam splitter, the first polarization beam splitter, the second polarization beam splitter, the first beam expander, the second beam expander, the first plane reflector and the second plane reflector. Therefore, the resolution, measurement accuracy and diffraction efficiency of the prepared large-area grating can be effectively guaranteed, thereby improving the quality of the prepared large-area grating.
[0075] In some embodiments, step S103 includes: transmitting the first light beam to the first optical fiber polarization controller through the single-mode optical fiber and transmitting the second light beam to the second optical fiber polarization controller through the single-mode optical fiber; step S104 includes: changing the polarization of the first light beam through the first optical fiber polarization controller, and polarizing the first light beam after polarization change into the first polarized light beam through the first polarization beam splitter; step S105 includes: changing the polarization of the second light beam through the second optical fiber polarization controller, and polarizing the second light beam after polarization change into the second polarized light beam through the second polarization beam splitter. The embodiments of the present invention can adjust the optical power of the light beam through the optical fiber polarization controller and the polarization beam splitter, so as to ensure the consistency of the interference power of the two light beams, so as to ensure the depth and uniformity of the grating.
[0076] It should be understood that the terms used in the present invention specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should also be understood that the term "and / or" used in the present invention specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.
[0077] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.
Claims
1. A holographic exposure system for preparing a grating, characterized in that: include: A light emitter, for emitting a light beam; A single-mode optical fiber, used for filtering the light beam and transmitting the filtered light beam to an optical fiber beam splitter; The optical fiber beam splitter is used to split the filtered light beam into a first light beam and a second light beam, and transmit the first light beam to a first polarization beam splitter through the single-mode optical fiber and transmit the second light beam to a second polarization beam splitter through the single-mode optical fiber; The first polarization beam splitter is used to polarize the first light beam into a first polarized light beam, and emit the first polarized light beam to a first beam expander through the single-mode optical fiber; The second polarization beam splitter is used to polarize the second light beam into a second polarized light beam, and emit the first polarized light beam to a second beam expander through the single-mode optical fiber, wherein the polarization of the first polarized light beam is consistent with that of the second polarized light beam; The first beam expander is used to expand the first polarized light beam to obtain a first interference light beam and propagate the first interference light beam to the first plane reflector; The second beam expander is used to expand the second polarized light beam to obtain a second interference light beam and propagate the second interference light beam to the second plane reflector; The first plane reflecting mirror is used to reflect the first interference light beam to an interference region, and the second plane reflecting mirror is used to reflect the second interference light beam to the interference region, so as to form a grating pattern on the surface of the substrate in the interference region.
2. The holographic exposure system according to claim 1, characterized in that: The first beam expander comprises a first off-axis parabolic reflector, the first polarized light beam emitted through the single-mode optical fiber is at a focal position of the first off-axis parabolic reflector, and the first off-axis parabolic reflector is used to expand the first polarized light beam into a parallel first interference light beam and reflect it to the first plane reflector; The second beam expander includes a second off-axis parabolic reflector. The second polarized light beam emitted through the single-mode optical fiber is located at the focal position of the second off-axis parabolic reflector. The second off-axis parabolic reflector is used to expand the second polarized light beam into a parallel second interference light beam and reflect it to the second plane reflector.
3. The holographic exposure system according to claim 2, characterized in that: The focal length of the first off-axis parabolic reflector is the same as the focal length of the second off-axis parabolic reflector, and the size of the first off-axis parabolic reflector is the same as the size of the second off-axis parabolic reflector.
4. The holographic exposure system according to claim 1, characterized in that: The first beam expander comprises a first lens, the first polarized light beam emitted through the single-mode optical fiber is at the focal position of the first lens, and the first lens is used to expand the first polarized light beam into a parallel first interference light beam and transmit it to the first plane reflector; The second beam expander includes a second lens, and the second polarized light beam emitted through the single-mode optical fiber is at the focal position of the second lens. The second lens is used to expand the second polarized light beam into a parallel second interference light beam and transmit it to the second plane reflector.
5. The holographic exposure system according to claim 4, characterized in that: The focal length of the first lens is the same as the focal length of the second lens, and the size of the first lens is the same as the size of the second lens.
6. The holographic exposure system according to any one of claims 1 to 5, characterized in that: The holographic exposure system further comprises: A first optical fiber polarization controller, disposed between the optical fiber beam splitter and the first polarization beam splitter, for adjusting the polarization of the first light beam to cooperate with the first polarization beam splitter to adjust the optical power of the first light beam; A second optical fiber polarization controller, disposed between the optical fiber beam splitter and the second polarization beam splitter, for adjusting the polarization of the first light beam to cooperate with the second polarization beam splitter to adjust the optical power of the second light beam; The optical power of the first polarized light beam is consistent with that of the second polarized light beam.
7. The holographic exposure system according to claim 6, characterized in that: The first optical fiber polarization controller and the second optical fiber polarization controller have the same property parameters.
8. The holographic exposure system according to claim 1, characterized in that: The optical transmitter comprises a fiber laser, and the fiber laser is connected to the single-mode optical fiber so that the light beam emitted by the fiber laser propagates along the single-mode optical fiber.
9. The holographic exposure system according to claim 1, characterized in that: The light transmitter includes a spatial laser, and the holographic exposure system further includes: A coupler is used to couple the light beam emitted by the spatial laser to the end face of the single-mode optical fiber, so that the light beam propagates along the single-mode optical fiber.
10. A holographic exposure method for preparing a grating, characterized in that: The holographic exposure system applied to any one of claims 1 to 9, the method comprising: filtering the light beam emitted by the light transmitter through the single-mode optical fiber and transmitting the filtered light beam to the optical fiber beam splitter; Splitting the filtered light beam into a first light beam and a second light beam by the optical fiber beam splitter; transmitting the first light beam to the first polarization beam splitter through the single-mode optical fiber and transmitting the second light beam to the second polarization beam splitter through the single-mode optical fiber; Polarizing the first light beam into a first polarized light beam through the first polarization beam splitter, and emitting the first polarized light beam to a first beam expander through the single-mode optical fiber; Polarizing the second light beam into a second polarized light beam through the second polarization beam splitter, and emitting the first polarized light beam to a second beam expander through the single-mode optical fiber, wherein the polarization of the first polarized light beam is consistent with that of the second polarized light beam; Expanding the first polarized light beam by the first beam expander to obtain a first interference light beam and transmitting the first interference light beam to the first plane reflector; Expanding the second polarized light beam by the second beam expander to obtain a second interference light beam and propagating the second interference light beam to the second plane reflector; The first interference light beam is reflected to an interference region by the first plane reflecting mirror, and the second interference light beam is reflected to the interference region by the second plane reflecting mirror, so as to form a grating pattern on the substrate surface in the interference region.