Method for exploring spatial self-phase modulation effect of two-dimensional material by using reflected light
By applying an opaque film on the surface of two-dimensional materials and using reflected light for excitation, the problem of inaccurate measurement in the nonlinear optical research of two-dimensional materials was solved, a clear spatial self-phase modulation effect was achieved, and the accuracy and efficiency of the research were improved.
Patent Information
- Application Number
- CN202510807382.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-09-16
AI Technical Summary
In the existing technology, when studying the nonlinear optics of two-dimensional materials in organic solvents, they are affected by gravity and thermal convection, resulting in inaccurate measurements of the nonlinear refractive index and third-order nonlinear polarizability. In addition, the SSPM effect is easily affected by material scattering and absorption, resulting in poor modulation effect.
Reflected light is used to excite two-dimensional materials. By applying an opaque polyvinyl alcohol film on the surface of a solid flexible material to eliminate the influence of the second reflection surface, the reflected light is used to excite the spatial self-phase modulation effect, and an optical path is constructed to receive the diffraction rings of the reflected light to study the nonlinear optical properties of the two-dimensional material.
It has achieved a clear and stable spatial self-phase modulation effect ring in two-dimensional materials, improved the accuracy and efficiency of the study of nonlinear optical effects, and provided a new way to study weakly transparent solid materials.
Smart Images
Figure CN120651787A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of nonlinear optical technology, and in particular to a method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light. Background Art
[0002] Polydimethylsiloxane (PDMS) is a silicone polymer with a flexible (Si-O) skeleton. When the PDMS prepolymer (Sylgard184-A) and the PDMS curing agent (Sylgard184-B) are mixed, the PDMS itself will complete the curing reaction due to the contact between the vinyl or allyl group and the silicone-based material. Adding two-dimensional material powder (such as Graphene, WS2, etc.) during the PDMS curing process can achieve the curing of the two-dimensional material, and finally obtain a solid flexible two-dimensional material based on PDMS. The SSPM diffraction rings of nonlinear materials in organic solvents often collapse due to the influence of gravity and thermal convection. This will greatly affect the measurement of the nonlinear refractive index and third-order nonlinear polarizability of the material itself, resulting in inaccurate characterization.
[0003] Spatial self-phase modulation (SSPM) is generally caused by third-order nonlinear optical effects, such as the optical Kerr effect and thermally induced nonlinear effects. The incident laser can cause the refractive index of the Kerr material to change, and the refractive index change in the medium in turn causes the light to phase shift. The light waves of the Gaussian beam have different radial phase shifts due to different light intensity distributions, and two different positions with the same wave vector can interfere with each other, resulting in diffraction rings. The number of diffraction rings is determined by the laser intensity and the magnitude of the nonlinear optical response of the material. Currently, SSPM-based studies of the third-order nonlinear optical response of two-dimensional materials mostly use transmitted light and the study of nonlinear two-dimensional materials in organic solvents. For example, PMMA / graphene solution is prepared to study the nonlinear optical properties of two-dimensional graphene. SSPM diffraction rings are obtained by irradiating a cuvette containing the PMMA / graphene solution through a lens using a laser. However, SSPM usually requires specific materials and light field conditions to achieve effective spatial self-phase modulation, and has certain requirements on the optical properties of the material and parameters such as the wavelength and intensity of light. The modulation effect may be affected by factors such as material scattering and absorption, resulting in a decrease in modulation efficiency and quality. This paper proposes a solution to use reflected light to explore the spatial self-phase modulation effect of two-dimensional materials. Summary of the Invention
[0004] The purpose of this invention is to provide a method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light. This method solves the problem of how to obtain a clear and stable spatial self-phase modulation effect ring in two-dimensional materials under the excitation of reflected light. This provides a new approach for studying the nonlinear optical effects of weakly transparent solid materials.
[0005] To achieve the above object, the present invention provides the following solutions:
[0006] A method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light includes: using reflected light to excite the two-dimensional material to obtain diffraction rings of the spatial self-phase modulation effect.
[0007] Optionally, the two-dimensional material is prepared from a solid flexible two-dimensional material based on polydimethylsiloxane.
[0008] Optionally, obtaining a spatial self-phase modulation ring by exciting a two-dimensional material with reflected light includes:
[0009] Laser is emitted by a laser, and the laser passes through a convex lens, the two-dimensional material, and a transmission ring receiving screen in sequence to form an optical path, and a diffraction ring receiving screen is placed on the side of the optical path to receive the spatial self-phase modulation diffraction ring of the reflected light.
[0010] Optionally, the surface of the two-dimensional material is coated with an opaque polyvinyl alcohol film.
[0011] The beneficial effects of the present invention are as follows: the present invention proposes a method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light. This method uniformly applies a polyvinyl alcohol film on the back surface of a solid flexible material to eliminate the dark reflection rings on the back surface of the solid flexible material, thereby obtaining SSPM rings under the excitation of laser reflected light. Finally, based on the relationship between the number of diffraction rings and the laser intensity, the n2 and n2 of the solid flexible two-dimensional material are obtained. It provides a new approach for studying the nonlinear optical effects of weakly transparent solid materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0013] Figure 1 Schematic diagram of the experimental optical path of the SSPM according to an embodiment of the present invention;
[0014] Figure 2 Detailed images of the solid flexible material (PDMS / WS2) and (PDMS / Graphene) samples according to the embodiments of the present invention;
[0015] Figure 3 The patterns of diffraction rings in the transmission and reflection experiments of the solid flexible material (PDMS / WS2) experimental sample at a wavelength of 532 nm according to an embodiment of the present invention;
[0016] Figure 4 The patterns of diffraction rings in transmission and reflection experiments of a solid flexible material (PDMS / Graphene) experimental sample at a wavelength of 532 nm according to an embodiment of the present invention are shown;
[0017] Figure 5 This is a curve showing the change in the number of diffraction rings as a function of light intensity in the transmission and reflection experiments of a solid flexible material (PDMS / WS2) under a 532nm laser according to an embodiment of the present invention;
[0018] Figure 6 This is a curve showing how the number of diffraction rings changes with light intensity in a transmission and reflection experiment of a solid flexible material (PDMS / Graphene) under a 532 nm laser according to an embodiment of the present invention. DETAILED DESCRIPTION
[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.
[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.
[0021] This embodiment provides a method for exploring the spatial self-phase modulation effect of a two-dimensional material using reflected light, including: using reflected light to excite the two-dimensional material to obtain spatial self-phase modulation diffraction rings.
[0022] Furthermore, the two-dimensional material is prepared from a solid flexible two-dimensional material based on polydimethylsiloxane.
[0023] Specifically, this embodiment prepared solid two-dimensional nonlinear materials (PDMS / WS2, PDMS / Graphene), such as Figure 2 As shown, the diffraction ring excited by the reflected light does not collapse, as shown in Figure 3 、 4 This is due to the fact that the two-dimensional material cured in PDMS is not affected by gravity and thermal convection.
[0024] The preparation of a solid two-dimensional nonlinear material sample in this embodiment includes the following steps:
[0025] (1) Add isopropyl ketone and two-dimensional material powder to a beaker; (2) Ultrasonicate for 2 hours to allow the material to overcome the interlayer van der Waals force and obtain a two-dimensional material with a few layers; (3) Add PDMS and ultrasonicate again for 2 hours to uniformly disperse the two-dimensional material in the PDMS; (4) Add a rotor and magnetically stir for 2 hours; (5) Add PDMS curing agent and stir for 1 hour; (6) Pour into a culture dish and let it stand for 1 hour to remove bubbles; (8) Heat at 85°C for 40 minutes to obtain a solid flexible two-dimensional material.
[0026] Furthermore, using reflected light to excite a two-dimensional material to obtain a spatial self-phase modulation ring includes:
[0027] Laser is emitted by a laser, and passes through a convex lens, a two-dimensional material, and a transmission ring receiving screen in sequence to form an optical path. A diffraction ring receiving screen is placed on the side of the optical path to receive the spatial self-phase modulation diffraction ring of the reflected light.
[0028] Specifically, build the SSPM experimental optical path, such as Figure 1 As shown: from left to right are 532nm laser, focusing lens (focal length 200mm), sample (sample is 120mm away from the lens), receiving screen (transmission), and a receiving screen on the side of the optical path for receiving reflected diffraction rings, which can receive SSPM diffraction rings of reflected light; a 532nm continuous laser (not limited to 532nm laser) is used as an excitation source to focus on a solid two-dimensional material, and the third-order nonlinear optical properties of the material are analyzed by observing the phase modulation effect of the reflected light. In this embodiment, the third-order nonlinear coefficient obtained by exciting the two-dimensional material with reflected light is better than the third-order nonlinear coefficient obtained by exciting the two-dimensional material with transmitted light. In the experiment, the n2 and As shown in Table 1, this provides a new approach for studying the nonlinear optical effects of weakly transparent solid materials.
[0029] Table 1
[0030]
[0031] Furthermore, the surface of the two-dimensional material is coated with an opaque polyvinyl alcohol film.
[0032] Specifically, before the experiment, a polyvinyl alcohol film needs to be evenly applied to the back surface of the solid material to eliminate the reflected light generated by the second reflective surface of the sample and obtain pure SSPM diffraction rings from the reflected light.
[0033] The method of this embodiment is further described below with reference to the accompanying drawings:
[0034] All raw materials used in the examples of the present invention were commercially available. The PDMS mentioned in the following examples is Liquid A in Dow Corning DC184 (polydimethylsiloxane with vinyl-reactive groups); the curing agent is Liquid B in Dow Corning DC184 (polydimethylsiloxane with hydrogen groups); Dow Corning DC184 is a two-component kit consisting of Liquids A and B, with an average molecular weight of ~25,000; and the opaque white facial mask, whose main component is polyvinyl alcohol, is a commercially available seven-seed powder eggshell facial mask.
[0035] The technical solutions of the embodiments of the present invention are as follows: (1) First, a method is used to analyze the third-order nonlinear optical properties of PDMS-based solid two-dimensional nonlinear materials (PDMS / WS2) and (PDMS / Graphene) by using the phase modulation effect of reflected light; (2) The prepared solid two-dimensional nonlinear material is subjected to SSPM reflection experiments, and the nonlinear refractive index and third-order nonlinear polarizability of the solid two-dimensional nonlinear material are calculated based on the law that the number of rings changes with light intensity. Specifically:
[0036] (I): A method for analyzing the third-order nonlinear optical properties of PDMS-based solid two-dimensional materials (PDMS / WS2) and (PDMS / Graphene) by using the phase modulation effect of reflected light. The specific operation method is as follows:
[0037] Step 1: Sample preparation process: (1) Add isopropyl ketone and two-dimensional material powder to a beaker; (2) Ultrasonicate for 2 hours to allow the material to overcome the interlayer van der Waals force and obtain a two-dimensional material with a few layers; (3) Add PDMS and ultrasonicate again for 2 hours to uniformly disperse the two-dimensional material in the PDMS; (4) Add a rotor and magnetically stir for 2 hours; (5) Add PDMS curing agent and stir for 1 hour; (6) Pour into a culture dish and let it stand for 1 hour to remove bubbles; (8) Heat at 85°C for 40 minutes to obtain a solid flexible two-dimensional material;
[0038] Step 2: Cut the prepared solid two-dimensional materials (PDMS / WS2) and (PDMS / Graphene) into 1×1 cm 2 , square shape with a thickness of 1mm;
[0039] Step 3: Take a small amount of opaque white mask whose main ingredient is polyvinyl alcohol and evenly cover the sample with a cotton swab;
[0040] Step 4: Place the coated sample in a culture dish and cure it at room temperature for 30 minutes to prepare the final sample for the SSPM experiment. This sample can eliminate the reflected light generated by the second reflective surface of the sample and obtain a pure SSPM diffraction ring from the reflected light.
[0041] (2) The prepared samples were subjected to SSPM experiment. The experimental equipment is as follows: Figure 1 As shown, from left to right are a continuous laser, a convex lens, a reflective ring receiving screen, solid two-dimensional nonlinear material (PDMS / WS2) and (PDMS / Graphene) samples, and a transmissive ring receiving screen. The laser used is a continuous laser with a Gaussian beam. The experiment is simple to operate and the theory is clear. The nonlinear refractive index and third-order nonlinear polarizability of solid two-dimensional nonlinear materials can be obtained through SSPM experiments. The laser used in the present invention is a 532nm visible light continuous laser, and the focusing lens is a 200mm convex lens, whose main function is to focus the light beam. The distance between the sample and the lens is crucial for SSPM. If the distance between the sample and the lens is too long, the diffraction rings will be distorted and the sample will be burned. If the distance between the sample and the lens is too close, the number of diffraction rings will be too small, making it impossible to obtain a more accurate optical nonlinear coefficient. After exploration, it was found that a distance of 12cm from the sample to the lens is more suitable. The nonlinear optical two-dimensional materials selected in this embodiment are WS2 and Graphene, which have strong nonlinear optical responses and can interact with the Gaussian continuous laser to produce SSPM diffraction rings. PDMS has a low nonlinear optical response, so WS2 and graphene were added to PDMS to prepare solid two-dimensional nonlinear materials. SSPM experiments were used to explore the nonlinear optical response of solid two-dimensional materials, and further calculations were performed to derive the nonlinear refractive index and third-order nonlinear polarizability of solid two-dimensional nonlinear materials. The specific operations are as follows:
[0042] Step 1: Build the SSPM experimental optical path, such as Figure 1 As shown: from left to right are 532nm laser, focusing lens (focal length 200mm), sample (sample is 120mm away from the lens), receiving screen (transmission), and a receiving screen on the side of the optical path for receiving reflected diffraction rings, which can receive the SSPM diffraction rings of reflected light;
[0043] Step 2: Place a solid flexible two-dimensional material without a polyvinyl alcohol film, adjust the laser power so that diffraction rings just appear on the receiving screen, record the laser power and diffraction rings, and conduct a transmission experiment;
[0044] Step 3: Increase the laser power at equal intervals and record the diffraction rings on the receiving screen;
[0045] Step 4: Evenly apply an opaque polyvinyl alcohol film on the rear surface of the solid flexible material;
[0046] Step 5: Increase the laser power at equal intervals, and continuously adjust the angle between the sample and the laser to make clear diffraction rings appear on the receiving screen, and record the diffraction rings on the receiving screen of the reflection ring;
[0047] According to the above steps, it can be observed that the SSPM effect can be observed in both the two-dimensional solid flexible material (PDMS / WS2) and (PDMS / Graphene) under the conditions of transmitted light and reflected light. By recording the relationship between the number of diffraction rings and the light intensity, and then using the nonlinear refractive index and the third-order nonlinear susceptibility The calculation formula [Wu L, Yuan X, Ma D, et al. Recent advances of spatial self-phase modulation in 2D materials and passive photonic device applications [J]. Small, 2020, 16 (35): 2002252.] can be used to obtain the third-order nonlinear coefficient of solid flexible materials.
[0048] According to the change of the number of diffraction rings at different light intensities, Figure 3 、 Figure 4 As shown in the figure, the nonlinear response coefficient of solid two-dimensional nonlinear materials at 532nm is calculated as follows: Figure 5 、 Figure 6 As shown, the nonlinear refractive index and third-order nonlinear polarizability of the solid two-dimensional nonlinear material were calculated, specifically: (n2 = 1.01×10 -4 cm 2 / W, (third-order nonlinear susceptibility) is 2.46×10 -7 esu; n2 for reflection experiment = 1.13×10 -4 cm 2 / W, (third-order nonlinear susceptibility) is 2.73×10 -7 esu); (PDMS / Graphene transmission experiment n2=1.06×10 -4 cm 2 / W, (third-order nonlinear susceptibility) is 2.57×10 -7 esu, n2 for reflection experiment = 1.47×10 -4 cm 2 / W, (third-order nonlinear susceptibility) is 3.59×10 -7 esu). According to the above data, we can get n2 and The results are better than those obtained from the transmission experiment, which shows that under certain specific conditions, when the use of transmitted light to study the nonlinear optical properties of two-dimensional materials is limited, the nonlinear optical properties of two-dimensional materials can be studied using reflected light.
[0049] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.
Claims
1. A method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light, characterized in that: include: The spatial self-phase modulation effect diffraction ring is obtained by using reflected light to excite the two-dimensional material.
2. The method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light according to claim 1, characterized in that: The two-dimensional material is prepared from a solid flexible two-dimensional material based on polydimethylsiloxane.
3. The method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light according to claim 1, characterized in that: The spatial self-phase modulation ring obtained by using reflected light to excite two-dimensional materials includes: Laser is emitted by a laser, and the laser passes through a convex lens, the two-dimensional material, and a transmission ring receiving screen in sequence to form an optical path, and a diffraction ring receiving screen is placed on the side of the optical path to receive the diffraction ring of the spatial self-phase modulation effect of the reflected light.
4. The method for exploring the spatial self-phase modulation effect of two-dimensional materials using reflected light according to claim 1, characterized in that: The surface of the two-dimensional material is coated with an opaque polyvinyl alcohol film.