A method for making and using a cutting combined lens

Abstract

A method for making and using a cut composite lens belongs to the field of photonic lattice technology. Convex lenses A and B with the same specifications are cut into three, four or five mirrors. The three mirrors have triangular hollow holes, the four mirrors have rectangular hollow holes, and the five mirrors have pentagonal hollow holes, which respectively form A parts. The central part of the convex lens B forms convex lens B parts of triangular parts, rectangular parts and pentagonal parts respectively. The convex lens B parts and the A parts are spliced ​​together to form cut composite lenses AB respectively. The designed cut composite lens can generate large-area (M+1) beam plane wave interference and irradiate LiNbO 3 :Fe photorefractive crystal, optically induced preparation of three-dimensional photonic lattice microstructure.

Description

Technical Field

[0001] The invention belongs to the technical field of photonic lattices and relates to a method for manufacturing and using a cutting combined lens. Background Art

[0002] The processing technology of photonic microstructures has always been a hot topic and focus of research. The current processes for manufacturing photonic microstructures include electron beam direct writing, two-photon absorption photopolymerization, colloidal self-assembly, etc. Light induction technology is a convenient method for manufacturing photonic microstructures. It uses optical methods, such as multi-beam interference or projection imaging, to optically induce many types of microstructures in photorefractive materials. At present, one-dimensional and two-dimensional optically induced photonic lattice structures have been widely reported, and many interesting new phenomena have been discovered. The refractive index distribution of the three-dimensional photonic lattice structure is periodically modulated in all dimensions, which means that the three-dimensional photonic microstructure may have better light wave modulation properties. However, at present, it is still a considerable challenge to prepare three-dimensional photonic lattice structures in bulk media by optical induction methods.

[0003] Application No. 201710240504.4 discloses a method for manufacturing a three-dimensional photonic lattice or a photonic quasicrystal, and provides a device for manufacturing a three-dimensional photonic lattice or a photonic quasicrystal structure. The device is provided with a laser, a beam expander, a multi-wedge prism with a central hole, and a photorefractive material from left to right. The laser, the beam expander, the multi-wedge prism with a central hole, and the photorefractive material are arranged on the same optical axis.

[0004] The processing of the central opening of a multi-wedge prism is difficult and has high production costs. In addition, the area where the central opening is cut is air, without a glass medium. As a result, the intensity and phase of the generated central light beam are inconsistent with the surrounding light beams. When interference occurs, the intensity of the central light beam is greater than that of the surrounding interference light beams, and there is a certain phase delay, which will have an adverse effect on the production of photonic lattice structures. Summary of the invention

[0005] The present invention aims at solving the problems in the prior art and provides a method for manufacturing and using a cut composite lens.

[0006] A cut composite lens comprises a convex lens A and a convex lens B of the same specification. The convex lens A is cut into three-part mirrors, four-part mirrors or five-part mirrors. The three-part mirror has a triangular hollow hole, the four-part mirror has a rectangular hollow hole, and the five-part mirror has a pentagonal hollow hole, which respectively form A components. The central part of the convex lens B forms a convex lens B component of a triangular component, a rectangular component and a pentagonal component respectively. The convex lens B component and the A component are spliced ​​together to form a cut composite lens AB respectively.

[0007] The triangular parts are inlaid and matched with the triangular hollow holes, the rectangular parts are inlaid and matched with the rectangular hollow holes, and the pentagonal parts are inlaid and matched with the pentagonal hollow holes.

[0008] A method for manufacturing a cutting combined lens uses two convex lenses A and convex lenses B with the same specifications, and after cutting and splicing processing, a cutting combined lens AB that meets the needs of multi-beam interference is combined.

[0009] The method comprises the following steps: cutting the convex lens A into three mirrors, four mirrors or five mirrors, and then splicing the three mirrors, four mirrors or five mirrors together to form a combined lens A3.

[0010] The central part of the combined lens A3 is cut, and the 3-point mirror forms a triangular hollow hole, the 4-point mirror forms a rectangular hollow hole, and the 5-point mirror forms a pentagonal hollow hole, forming A5 components respectively.

[0011] The outer part of the convex lens B is cut off, and the central part of the convex lens B forms a convex lens B2 part consisting of a triangular part, a rectangular part and a pentagonal part.

[0012] The triangular parts are inlaid and matched with the triangular hollow holes, the rectangular parts are inlaid and matched with the rectangular hollow holes, and the pentagonal parts are inlaid and matched with the pentagonal hollow holes.

[0013] The matched convex lens B2 component and A5 component after cutting are spliced ​​together to form the cut combined lenses AB respectively.

[0014] A method for using a cutting combined lens, using the cutting combined lens to generate a wide range of three-dimensional lattice interference light fields, optically inducing a large volume of three-dimensional photonic lattice structure in an iron-doped lithium niobate LiNbO3Fe photorefractive crystal, the cross-sectional area of ​​the interference light field generated by the cutting combined lens is about 140mm 2 , beam configuration of (4+1) plane wave interference, numerical simulation results of the three-dimensional lattice light field intensity distribution generated by (4+1) plane wave interference in different cross sections, the optical axis direction of the system is set to the z-axis, in the region of (4+1) plane wave interference, the spatial intensity distribution of the light field shows significant periodicity in all three dimensions, which is used to optically induce the generation of three-dimensional photonic lattice structures.

[0015] A method for using a cutting combination lens, using a single component - the cutting combination lens to generate a large area of ​​(M+1) light beams, and irradiate a LiNbO3:Fe photorefractive crystal, optically inducing the preparation of a three-dimensional photonic lattice microstructure, after being divided and transformed by the cutting combination lens, generating (4+1) plane wave interference as a lattice forming beam. The lattice forming beam irradiates a photorefractive lithium niobate crystal with a size of 10mm*10mm*5mm, doped with 0.03wt% of Fe, and induces a three-dimensional photonic lattice structure in the crystal.

[0016] The advantages of the present invention are: it overcomes the common shortcomings of the traditional multi-beam interference generation method, that is, the system is complex and difficult to adjust. The proposed cutting and combining lens can generate a large-area three-dimensional interference light field, which is used for light-induced production of three-dimensional photonic lattice microstructures. The method and device for generating multi-beam interference using the cutting and combining lens has a simple structure, is very stable, and has low cost, which greatly improves the production efficiency of three-dimensional photonic lattice microstructures.

[0017] The most commonly used optical element, convex lens, is selected, cut and combined to form a single component that can generate (M+1) plane wave interference. The use of cut and combined lenses avoids the complex adjustment equipment required by the traditional multi-beam interference method, making the light-induced production device of the photonic lattice simpler and more stable, and does not rely on a precise and complex adjustment system. The cut and combined lens has a large light-transmitting area, which can produce a large area of ​​multi-beam interference and improve the preparation efficiency of the photonic lattice. The cut and combined lens has great flexibility. By controlling the ratio of the parameter a and the focal length f of the cut and combined lens during processing, the fringe period size of the interference light field can be flexibly adjusted, thereby producing three-dimensional photonic lattices with different period scales. The cut and combined lens also has good scalability. By controlling the number of petals of the cut lens A during processing, multi-beam interference with different interference numbers (for example: 3+1, 4+1, 5+1, 6+1...) can be produced, thereby producing three-dimensional photonic lattice microstructures of different lattice types.

[0018] The use of cut and combined lenses can easily realize a large-area three-dimensional interference light field, thereby light-induced production of large-volume three-dimensional photonic lattice microstructures in photorefractive crystals. This method overcomes the shortcomings of the traditional multi-beam interference method, which is complex and difficult to adjust. The proposed production device has a simple structure, is very stable, and has low cost, greatly improving the production efficiency of three-dimensional photonic lattice microstructures.

[0019] A single component, a cut combined lens, is used to generate a large area (M+1) beam, which is shot into a LiNbO3:Fe photorefractive crystal to optically induce the preparation of a three-dimensional photonic lattice microstructure. Planar guided wave intensity imaging and far-field diffraction patterns are used to observe and verify the optically induced microstructure in the crystal. This method is flexible, inexpensive, and does not require complex adjustment devices. It can be performed in almost all optical laboratories. It also has good flexibility and scalability. By appropriately designing the cut combined lens, other types of periodic and quasi-periodic three-dimensional photonic lattice structures can be easily manufactured.

[0020] The commonly used convex lens is processed to produce a cut and spliced ​​lens. Lenses are common optical components, and it is relatively easy to cut and bond them without drilling holes in glass components. The generated central light beam is converted into parallel light through the convex lens B2 component, and no additional phase delay is introduced. Each interference beam is generated through the glass component, and the light intensity of each interference beam is equal, which is more conducive to the production of photonic lattice structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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 or the prior art descriptions. 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 creative work. As shown in the figure:

[0022] Fig. 1(a) Design and processing of cutting combination lens.

[0023] FIG1( b ) is a schematic diagram of the interference of two plane waves using a combined lens A3.

[0024] FIG1( c ) is a schematic diagram of (2+1) plane wave interference using a cut combination lens AB.

[0025] FIG2( a ) shows a method for manufacturing a composite lens (CCL) capable of generating (4+1) plane wave interference.

[0026] Fig. 2(b), Schematic diagram of the (4+1) plane wave interference transmission scheme.

[0027] Fig. 2(c) is a computer simulation of the intensity distribution pattern generated by the (4+1) plane wave in the cross section (xy plane) perpendicular to the optical axis.

[0028] Fig. 2(d) Numerical simulation of the side view of the light field with (4+1) plane wave interference.

[0029] Fig. 3(a) Schematic diagram of the experimental setup for fabricating and observing three-dimensional photonic lattice microstructures in photorefractive crystals.

[0030] FIG3( b ) is the intensity pattern of the lattice-forming beam captured by the CCD on the front surface of the crystal at the initial moment.

[0031] Fig. 3(c) is a planar guided wave intensity image of the induced three-dimensional photonic lattice structure captured in the xy plane of the crystal.

[0032] Figure 3(d), top: planar guided wave intensity image of the induced three-dimensional photonic lattice structure captured in the plane of the crystal, bottom: far-field emission pattern of the induced three-dimensional photonic lattice structure captured in the xy plane.

[0033] FIG4( a ) shows a method for producing a combined lens capable of generating (3+1) plane wave interferences.

[0034] FIG4( b ) is a numerical simulation of the intensity distribution of a periodic three-dimensional lattice light field generated by using the cut combination lens designed in FIG4( a ).

[0035] FIG4( c ) is a numerical simulation of the intensity distribution of a periodic three-dimensional lattice light field generated by using the cut combination lens designed in FIG4( a ).

[0036] FIG4( d ) shows a method for producing a combined lens that can generate (5+1) plane wave interference by cutting.

[0037] FIG4( e ) is a numerical simulation of the intensity distribution of the quasi-periodic three-dimensional lattice light field generated using the cut combination lens designed in FIG4( d ).

[0038] FIG4( f ) is a numerical simulation of the intensity distribution of the quasi-periodic three-dimensional lattice light field generated using the cut combination lens designed in FIG4( d ). 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 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 creative work are within the scope of protection of the present invention.

[0040] Embodiment 1: As shown in FIG. 2( a ), a method for manufacturing a cut composite lens is provided, wherein two convex lenses A and B having the same specifications are used, and after cutting and splicing processing, a cut composite lens AB that meets the requirements of multi-beam interference is assembled.

[0041] The method comprises the following steps: cutting the convex lens A into four mirrors, and then splicing the four mirrors together to form a four-mirror combined lens A3.

[0042] The center portion of the 4-mirror combined lens A3 is cut to form a combined lens A3 having a rectangular hollow hole.

[0043] The outer part of the convex lens B is cut off, and the central part of the convex lens B forms a B2 component which is a rectangular component. The rectangular component is inlaid and matched with the rectangular hollow hole.

[0044] The cut and matched combined lens A3 and B2 components with rectangular hollow holes are spliced ​​together to form a cut combined lens AB.

[0045] Furthermore, the splicing is bonding, or the splicing is laminating, and the smaller the gap between the laminating parts is, the better.

[0046] Embodiment 2: As shown in FIG. 4( a ), a method for manufacturing a cut composite lens is provided, wherein two convex lenses A and convex lenses B having the same specifications are cut and spliced ​​to form a cut composite lens AB that meets the requirements of multi-beam interference.

[0047] The method comprises the following steps: cutting the convex lens A into three mirrors, then splicing the three mirrors together to form a three-mirror combined lens A3, and cutting the central part of the three-mirror combined lens A3 to form a combined lens A3 with a triangular hollow hole.

[0048] The outer part of the convex lens B is cut off, and the central part of the convex lens B forms a triangular component B3, and the triangular component is inlaid and matched with the triangular hollow hole.

[0049] The cut and matched combined lens components A3 and B3 with triangular hollow holes are spliced ​​together to form a cut combined lens AB.

[0050] Embodiment 3: As shown in FIG. 4( d ), a method for manufacturing a cut composite lens is provided, which uses two convex lenses A and B with the same specifications, and after cutting and splicing processing, a cut composite lens AB that meets the requirements of multi-beam interference is combined.

[0051] The method comprises the following steps: cutting the convex lens A into five mirrors, then splicing the five mirrors together to form a five-mirror combined lens A3, and cutting the central part of the five-mirror combined lens A3 to form a combined lens A3 with a pentagonal hollow hole.

[0052] The outer part of the convex lens B is cut off, and the central part of the convex lens B forms a convex lens B5 component which is a pentagonal component. The pentagonal component is inlaid and matched with the pentagonal hollow hole.

[0053] The cut and matched combined lens A3 and B5 parts with pentagonal hollow holes are spliced ​​together to form a cut combined lens AB.

[0054] Example 4: As shown in Figure 1(a), Figure 1(b), Figure 1(c), Figure 2(a), Figure 2(b), Figure 2(c), Figure 3(a), Figure 3(b), Figure 3(c), Figure 3(d), Figure 4(a), Figure 4(b), Figure 4(c), Figure 4(d), Figure 4(e) and Figure 4(f).

[0055] By using two convex lenses A and convex lenses B with the same specifications and after appropriate cutting and splicing processing, a cutting combination lens AB that meets the needs of multi-beam interference can be combined.

[0056] In FIG1(a), convex lens A and convex lens B are two convex lenses with the same focal length f, the same diameter, and the same material (optical glass). First, a portion of the middle width a of convex lens A is cut off, and then the remaining two portions are spliced ​​together to form a combined lens A3.

[0057] The combined lens A3 can generate two wide plane wave interferences, as shown in Figure 1(b), and the interference region has a large interference area. The angle θ between the interference beam and the optical axis is determined by the parameter a and the focal length f, and satisfies the relationship θ=arctan(a / 2f), that is, by setting the ratio of the parameter a and the focal length f, the angle of the interference beam can be flexibly adjusted, thereby adjusting the period size of the interference fringes.

[0058] Next, cut off the width b from the middle part of the combined lens A3, that is, cut off the upper and lower parts of the combined lens A3 by a width of b / 2, respectively. This becomes the A5 component in Figure 1(a).

[0059] Then the outer part of the convex lens B is cut off, leaving only a small part with a width b in the middle, such as B2 shown in the lower part of Figure 1(a).

[0060] Finally, the cut convex lens component B2 and the cut convex lens component A5 are spliced ​​together to form a cut combined lens AB, as shown in FIG. 1( a ).

[0061] When the point light source is located at the focus of the cut combination lens AB, interference of (2+1) plane waves can be generated, as shown in Figure 1(c). The intensity distribution of the interference light field shows a relatively long periodic change along the optical axis.

[0062] Here, the ratio of parameter a to the focal length f of the lens affects the period of the lattice points in the interfering light field. Parameter b affects the overall size of the interference region.

[0063] Therefore, by appropriately setting the values ​​of the parameters a, b, and f, the lattice period and the irradiation area of ​​the interference light field can be flexibly adjusted.

[0064] Embodiment 5: As shown in FIG. 1(a), FIG. 1(b), FIG. 1(c), FIG. 2(a), FIG. 2(b), FIG. 2(c), FIG. 3(a), FIG. 3(b), FIG. 3(c), FIG. 3(d), FIG. 4(a), FIG. 4(b), FIG. 4(c), FIG. 4(d), FIG. 4(e) and FIG. 4(f),

[0065] A method for manufacturing a cut composite lens comprises the following steps:

[0066] By uniformly cutting the convex lens A into M parts and appropriately combining them with the cut B2 components, interference of (M+1) plane waves can be generated.

[0067] As an example, using a cut-and-difference lens (ie, M=4) produces (4+1) plane wave interferences.

[0068] The design and processing method of the cut composite lens used is shown in FIG2( a ).

[0069] The thin convex lens C and the thin convex lens D have the same specifications, the diameter of the lens is 60 mm, and the focal length f is 120 mm. Here, the parameters a=8.5 mm and b=12.0 mm.

[0070] Cut the convex lens C into four equal parts, cut off a / 2 of the right-angled side of each part, and then cut off the right-angled area of ​​each part to form an equal-sized right triangle, so that the base of the right triangle is b.

[0071] The next step is to splice and glue the cut parts C1, C2, C3, and C4 together to form the C5 assembly.

[0072] Cut off the outer part of the convex lens D and keep only the middle part D1.

[0073] Finally, the D1 part and the C5 component are bonded together to form a cut composite lens CCL that can generate (4+1) plane wave interference.

[0074] The beam configuration of (4+1) plane wave interference is shown in Figure 2(b). Since the transparent area of ​​the cut lens assembly is large, it can generate a large-area three-dimensional lattice light field. According to the measurement, the cross-sectional area of ​​the interference light field generated by the cut lens assembly is about 140mm 2 .

[0075] Example 6: A method for using a cut composite lens, in a potassium ferrite-doped photorefractive crystal, optically induces a three-dimensional photonic lattice by (4+1) plane wave interference, and observes and verifies the induced three-dimensional lattice microstructure by plane waveguide intensity imaging and far-field diffraction pattern. This method is inexpensive and does not require complex adjustment devices. In addition, it is flexible and scalable. This method can be used to manufacture other more complex three-dimensional photonic lattice microstructures by appropriately designing a cut composite lens.

[0076] A method for using a cutting combination lens comprises the following steps: designing and manufacturing a cutting combination lens, using the cutting combination lens to generate a wide range of three-dimensional lattice interference light fields, and optically inducing a large volume of three-dimensional photonic lattice structure in an iron-doped lithium niobate (LiNbO3Fe) photorefractive crystal.

[0077] The experimental device used in this method is very simple and compact, and the components are cheap and easy to obtain at low cost. The whole system can be used under almost all basic optical laboratory conditions. This method has high production efficiency and good scalability, and can be applied to other photosensitive materials to make photonic microstructures on different substrates.

[0078] Multi-beam interference can produce many types of periodic and quasi-periodic light intensity grid patterns. When (M+1) plane waves interfere, various three-dimensional lattice light fields can be generated. However, most traditional setups for multi-beam interference are complex and expensive. Using a single component to achieve multi-beam interference can greatly reduce the complexity of the experimental setup. Lenses are common optical elements in optical experiments and are relatively easy to process. In addition, secondary processing such as cutting and splicing is easy. Under appropriate conditions, a thin convex lens can convert a spherical wave emitted by a point light source into an approximate plane wave. After cutting the convex lens and combining it in some appropriate ways, different interference phenomena can be presented, such as Meislin lens, Bissell lens, etc.

[0079] Embodiment 7: A method for manufacturing a cut combination lens, using a single component to generate a three-dimensional lattice light field, for optically induced manufacturing of a three-dimensional photonic lattice structure.

[0080] It also contains the following steps: cutting two thin convex lenses separately and combining them appropriately to form a cut combined lens. This can generate (M+1) plane wave interferences. Its basic principle and design method are as follows Figure 1(a)-Figure 1(c) shown.

[0081] In Figure 1(a), A and B are two thin convex lenses with the same focal length f. First, a portion of the middle width a of the convex lens A is cut off, and then the remaining two portions are spliced ​​together to form a combined lens A3. According to the characteristics of the thin convex lens, the focal plane of the combined lens A3 coincides with the focal plane of the original convex lens A. When the point light source S is located at the intersection of the central optical axis and the focal plane of the combined lens, the spherical wave emitted by the point light source S is split by the upper and lower parts of the combined lens and undergoes waveform transformation.

[0082] This causes the two wide plane waves to interfere, as shown in Figure 1(b). As can be seen from the figure, the interference region has a larger area. The angle between the interfering beam and the optical axis is determined by the parameter a and the focal length f, that is, θ = arctan (a / 2f). Next, the width b is cut off from the middle part of A3, that is, the upper and lower parts of A3 with a width of b / 2 are cut off respectively.

[0083] This becomes the A5 component, shown in the middle of Figure 1(a).

[0084] Then, the outer part of the convex lens B is cut off, leaving only a small part of the middle width B, as shown in the lower part of Figure 1(a) B2. Here, B2 is still a standard thin convex lens with a focal length of f, but the aperture has been reduced. Obviously, when the point light source is located at the focus of B2, the spherical wave emitted by the point light source can be converted into a plane wave propagating along the optical axis. Finally, the convex lens B2 and element A5 are spliced ​​together so that B2 and A5 have the same focal plane.

[0085] In this way, it forms a cutting combination lens AB, as shown in Figure 1 (a). When the point light source is located at the focus of the cutting combination lens AB (i.e., the focus of B3), the spherical wave emitted by the point light source is split by the upper, middle and lower parts of the cutting combination lens. Each part of the split spherical wave is converted into a plane wave.

[0086] Among them, the plane waves generated by the upper and lower parts of the cut combination lens are deflected toward the central optical axis of the system. On the contrary, the plane waves generated in the middle part propagate in the direction of the central optical axis.

[0087] These three plane waves overlap and interfere during propagation.

[0088] This forms an interference field of (2+1) plane waves in the overlapping region, as shown in Figure 1(c). The intensity distribution of the interference light field exhibits relatively long periodic changes along the optical axis. Here, the ratio of parameter a to the focal length f of the lens affects the period of the lattice points in the interference light field. Parameter b affects the overall size of the interference region. Therefore, by appropriately setting the values ​​of parameters a, b, and f, the lattice period and irradiation area of ​​the interference light field can be flexibly adjusted.

[0089] Based on the above principle, by uniformly cutting a thin convex lens into M parts and combining them appropriately, interference of (M+1) plane waves can be generated.

[0090] Using a properly designed cut-and-combined lens (ie, M=4) produces (4+1) plane wave interferences.

[0091] The method also includes the following steps: a processing step of cutting the combined lens, as shown in FIG2(a). The thin convex lenses C and D have the same specifications, both with a diameter of 60 mm and a focal length of 120 mm. Here, the parameters a = 8.5 mm and b = 12.0 mm. Since the transparent area of ​​the cut combined lens assembly is large, it can generate a large-area three-dimensional lattice light field.

[0092] According to the measurement, the cross-sectional area of ​​the interference light field generated by the cut combination lens is about 140mm 2The beam configuration of (4+1) plane wave interference is shown in Figure 2(b). The numerical simulation results of the three-dimensional lattice light field intensity distribution generated by (4+1) plane wave interference in different cross sections are shown in Figure 2(c) and Figure 2(d). Here, the optical axis direction of the system is set to the z-axis.

[0093] It can be observed that in the region of (4+1) plane wave interference, the spatial intensity distribution of the light field exhibits remarkable periodicity in all three dimensions, which can be used to optically induce the generation of three-dimensional photonic lattice structures.

[0094] Figure 2 (a) A method for fabricating a composite lens (CCL) that can generate (4+1) plane wave interference. (b) Schematic diagram of the (4+1) plane wave interference emission scheme.

[0095] Figure 2(c) Computer simulation of the intensity distribution pattern generated by the (4+1) plane wave in the cross section (xy plane) perpendicular to the optical axis. The upper right inset is a simulation of the far-field diffraction pattern of the structure shown in the xy plane. The vector arrow T indicates the vertical direction along the figure, and the vector arrow D indicates the diagonal direction of the figure.

[0096] Figure 2(d) Numerical simulation of the side view of the light field with (4+1) plane wave interference. Top: Side view profile of the interference light field in the direction of vector arrow T.

[0097] During the production process, a Nd:YAG continuous wave laser (wavelength = 532nm, output power P = 200mw) was used as a coherent light source. A He-Ne laser with a wavelength of 632.8nm and an output power of 1.5mw was used as a detection light source.

[0098] The schematic diagram of the experimental setup for fabricating and verifying the optically induced three-dimensional photonic lattice structure is shown in Figure 3(a). S1 and S2 are optical path selection switches.

[0099] When S1 is turned on and S2 is turned off, optical path ① is used to optically induce the fabrication of a three-dimensional photonic lattice, and the CCD is turned off in this state.

[0100] The Gaussian beam emitted by the Nd:YAG laser is expanded and filtered by a spatial filter to form a divergent spherical wave.

[0101] It also contains the following steps: after segmentation and transformation by cutting the combined lens, (4+1) plane wave interference is generated as a lattice forming beam. The lattice forming beam irradiates a photorefractive lithium niobate crystal with a size of 10mm*10mm*5mm, doped with 0.03wt% Fe, and induces a three-dimensional photonic lattice structure in the crystal.

[0102] When S2 is turned on and S1 is turned off, light path ② is used to observe and detect the optically induced three-dimensional photonic lattice in the crystal.

[0103] The CCD operates in this state. By adjusting the position of the imaging lens and the aperture of the iris, the CCD can capture the planar guided wave intensity and far-field diffraction pattern of the optically induced photonic lattice structure.

[0104] Typical results are Figure 3(b)-Figure 3(d) shown.

[0105] Figure 3(b) shows the intensity distribution pattern of the lattice forming beam on the front surface of the Li NbO 3 :Fe crystal captured by the CCD at the initial time.

[0106] Figures 3(c) and 3(d) show the plane guided wave intensity images captured in different directions of the three-dimensional photonic lattice structure induced in the crystal when illuminated by a broad plane wave.

[0107] The plane guided wave intensity image clearly shows that the induced lattice in the crystal is a three-dimensional structure. All scales in the figure are 15μm. When observed from the front and side, this induced lattice structure exhibits a periodic refractive index distribution.

[0108] The induced structure presents a square lattice distribution on the front side and a long period structure on the side. These characteristics are similar to the numerical simulation results of the spatial distribution of the three-dimensional lattice light field intensity in Figure 2(c) and Figure 2(d). This indicates that a three-dimensional photonic lattice structure is optically induced in the LiNbO3:Fe crystal. Due to the large transmission area of ​​the cut combination lens, the area of ​​the interference region is larger than the size of the crystal.

[0109] Therefore, the induced microstructure is distributed throughout the crystal. This method has high production efficiency. If the size of the photorefractive crystal is increased, the area and volume of the induced lattice microstructure can be further expanded.

[0110] Fig. 3(a) Schematic diagram of the experimental setup for fabricating and observing three-dimensional photonic lattice microstructures in photorefractive crystals.

[0111] The far-field diffraction pattern is also an effective test method to verify the refractive index distribution characteristics of the microstructure. The lower part of Figure 3(d) shows the far-field diffraction pattern captured by the CCD in the focal plane behind the imaging lens when the probe beam illuminates the optically induced microstructure in the crystal. A set of different diffraction peaks with a regular pattern can be observed in this figure, which is very similar to the far-field diffraction pattern in Section 2(c). The only difference is that the diffraction spots in the far-field diffraction pattern captured by the CCD are brighter in the horizontal direction (parallel to the c-axis of the LiNbO3:Fe crystal) but not as bright in the vertical direction. This phenomenon is caused by the anisotropic properties of the lithium niobate crystal. The observation of the far-field diffraction pattern once again proves that the three-dimensional photonic lattice has been induced in the crystal.

[0112] As shown in Figures 4(a), 4(b), 4(c), 4(d), 4(e) and 4(f), the experimental method has good flexibility and scalability. On the one hand, the degree and area of ​​multi-beam interference can be controlled by changing the parameters a, b and focal length f of the cut combination lens. This allows flexible adjustment of the lattice period and manufacturing area of ​​the optically induced microstructure. On the other hand, by properly designing the cut combination lens, interference of a variety of (M+1) surface waves can be generated. This is suitable for making more complex periodic and quasi-periodic three-dimensional microstructures. For simplicity, its feasibility is demonstrated by numerical simulation.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cutting combined lens, characterized in that: Convex lens A and convex lens B have the same specifications. The convex lens A is cut into 3-point mirror, 4-point mirror or 5-point mirror. The 3-point mirror has a triangular hollow hole, the 4-point mirror has a rectangular hollow hole, and the 5-point mirror has a pentagonal hollow hole. After the convex lens A is cut, each cutting edge cuts off a portion of width a / 2, and a hollow hole with a side length of b is cut out in the center to form an A5 component. The central part of the convex lens B is cut into a triangular component, a rectangular component and a pentagonal component B2 with a side length of b. The B2 component is inlaid in the middle of the A5 component. The triangular component is inlaid with the triangular hollow hole to match the combination, the rectangular component is inlaid with the rectangular hollow hole to match the combination, and the pentagonal component is inlaid with the pentagonal hollow hole to match the combination. Alternatively, a portion of the middle width a of the convex lens A is cut off, and then the upper and lower portions are cut off by width b / 2 respectively to form component A5. The convex lens B leaves component B2 with a middle width b, and then component B2 is embedded in the middle of component A5. The diameters of convex lenses A and B are both 60 mm, and the focal lengths are both 120 mm. The parameters a=8.5 mm, b=12.0 mm, forming a cut composite lens AB.

2. A method for manufacturing a cut composite lens, using two convex lenses A and convex lenses B with the same specifications, and combining them into a cut composite lens AB after cutting and splicing. In the step of cutting the convex lens A into two parts, a portion of the convex lens A with a middle width of a is cut off, and then the upper and lower portions are cut off by a width of b / 2 to form an A5 component, and a B2 component with a middle width of b is left from the convex lens B, and then the B2 component is inlaid in the middle of the A5 component to form a cut composite lens AB; Alternatively, for the step of cutting the convex lens A into three-part mirrors, four-part mirrors or five-part mirrors, a portion of width a / 2 is cut off from each cutting edge, and a hollow hole with a side length of b is cut out in the center portion, so that the three-part mirror forms a triangular hollow hole, the four-part mirror forms a rectangular hollow hole, and the five-part mirror forms a pentagonal hollow hole, forming A5 components respectively. A triangular component, a rectangular component and a pentagonal component B2 components with a side length of b are cut out from the center portion of the convex lens B, and then the B2 component of the corresponding shape is inlaid in the middle of the A5 component to form a cut composite lens AB.

3. The method for manufacturing a cut composite lens according to claim 2, characterized in that: The method comprises the following steps: splicing three mirrors, four mirrors or five mirrors together to form a combined lens A3; The center part of the combined lens A3 is cut, and the 3-point mirror forms a triangular hollow hole, the 4-point mirror forms a rectangular hollow hole, and the 5-point mirror forms a pentagonal hollow hole, forming A5 components respectively. The outer part of the convex lens B is cut off, and the central part of the convex lens B forms a convex lens B2 part consisting of a triangular part, a rectangular part and a pentagonal part. The triangular parts are matched with the triangular hollow holes, the rectangular parts are matched with the rectangular hollow holes, and the pentagonal parts are matched with the pentagonal hollow holes. The matched convex lens B2 component and A5 component after cutting are spliced ​​together to form the cut combined lenses AB respectively.

4. The method for manufacturing a cut composite lens according to claim 2, characterized in that: The method further comprises the following steps: cutting the convex lens A and the convex lens B respectively, dividing the convex lens A into M parts, where M=2, 3, 4, or 5, combining the cut convex lens A and the convex lens B to form a cut combined lens, and generating (M+1) plane waves. When M=2, a portion of the middle width a of the convex lens A is cut off, and then the remaining two portions are spliced ​​together to form a combined lens A3. The focal plane of the combined lens A3 coincides with the focal plane of the original convex lens A. When the point light source S is located at the intersection of the central optical axis and the focal plane of the combined lens, the spherical wave emitted by the point light source S is split by the upper and lower parts of the combined lens and undergoes waveform transformation. This causes the two plane waves to interfere with each other, and the angle between the interfering beam and the optical axis is determined by the parameter a and the focal length f, that is, θ =arctan(a / 2f), cut off the width of b from the middle part of A3, that is, cut off the upper and lower parts of A3 with a width of b / 2 respectively, and become the A5 component. The outer part of the convex lens B is cut off, leaving a small part of the middle width B, forming a standard convex lens B2 with a focal length of f. When the point light source is located at the focus of the convex lens B2, the spherical wave emitted by the point light source can be converted into a plane wave propagating along the optical axis. The convex lens B2 and the A5 component are spliced ​​together. The convex lens B2 and the A5 component have the same focal plane. After splicing, a cutting combination lens AB is formed. When the point light source is located at the focus of the cutting combination lens AB, that is, the focus of B2, the spherical wave emitted by the point light source is divided by the upper, middle and lower parts of the cutting combination lens, and each part of the divided spherical wave is converted into a plane wave. The plane waves generated by the upper and lower parts of the cut combination lens are deflected toward the central optical axis of the system. On the contrary, the plane wave generated in the middle part propagates in the direction of the central optical axis. These three plane waves overlap and interfere during the propagation process. This forms an interference field of (2+1) plane waves in the overlapping area. The intensity distribution of the interference light field shows a relatively periodic change along the optical axis. The ratio of parameter a to the focal length f of the lens affects the period of the lattice points in the interference light field. Parameter b affects the overall size of the interference area. By setting the values ​​of parameters a, b and f, the lattice period and irradiation area of ​​the interference light field can be adjusted. Or: By evenly cutting convex lens A into M parts and combining the cut convex lens A with convex lens B, (M+1) plane wave interference is generated. Using the cut combined lens, when M=4, (4+1) plane wave interference is generated.

5. The method for manufacturing a cut composite lens according to claim 2, characterized in that: The processing steps of cutting the combined lens, the specifications of convex lens A and convex lens B are the same, the diameter is 60 mm, the focal length is 120 mm, the parameters are a=8.5 mm, b=12.0 mm.

6. A method for using a cut composite lens, wherein the cut composite lens is prepared by the method for preparing a cut composite lens according to any one of claims 2 to 5, characterized in that: Use a cut composite lens. The cut composite lens is as follows: a portion of the middle width a of the convex lens A is cut off, and the upper and lower parts are cut off by width b / 2 to form an A5 component. The convex lens B leaves a B2 component with a middle width b, and the B2 component is inlaid in the middle of the A5 component to form a cut composite lens AB. Alternatively, the cut composite lens is as follows: the convex lens A is cut into 3, 4 or 5 mirrors, each cut edge cuts off a portion of width a / 2, and a hollow hole with a side length of b is cut out in the center, the 3-mirror forms a triangular hollow hole, the 4-mirror forms a rectangular hollow hole, and the 5-mirror forms a pentagonal hollow hole, forming A5 components respectively, and a triangular component, a rectangular component and a pentagonal component B2 with a side length of b are cut out from the center of the convex lens B, and then the B2 component of the corresponding shape is inlaid in the middle of the A5 component to form a cut composite lens AB; Generate a three-dimensional lattice interference light field, optically induce a three-dimensional photonic lattice structure in the iron-doped lithium niobate LiNbO3Fe photorefractive crystal, divide the convex lens A into M parts, and cut the combined lens to generate (M+1) beams. The cross-sectional area of ​​the interference light field generated by the cut combined lens is 140mm 2 , M is 4, which is the beam configuration of (4+1) plane wave interference. For the numerical simulation results of the three-dimensional lattice light field intensity distribution generated by (4+1) plane wave interference in different cross sections, the optical axis direction of the system is set to the z-axis. In the region of (4+1) plane wave interference, the spatial intensity distribution of the light field shows periodicity in all three dimensions, which is used to optically induce the generation of a three-dimensional photonic lattice structure.

7. A method for using a cut composite lens, wherein the cut composite lens is prepared by the method for preparing a cut composite lens according to any one of claims 2 to 5, characterized in that: Using a single component - the cut-combination lens to generate (M+1) beams, The cut composite lens is as follows: a portion of the middle width a of the convex lens A is cut off, and the upper and lower portions are cut off by a width b / 2 respectively to form an A5 component, and a B2 component with a middle width b of the convex lens B is left, and the B2 component is inlaid in the middle of the A5 component to form a cut composite lens AB; Alternatively, the cut composite lens is as follows: the convex lens A is cut into 3, 4 or 5 mirrors, each cutting edge cuts off a portion of width a / 2, and a hollow hole with a side length of b is cut out in the center, the 3-mirror forms a triangular hollow hole, the 4-mirror forms a rectangular hollow hole, and the 5-mirror forms a pentagonal hollow hole, forming A5 components respectively, and a triangular component, a rectangular component and a pentagonal component B2 component with a side length of b are cut out from the center of the convex lens B, and then the B2 component of the corresponding shape is embedded in the middle of the A5 component to form a cut composite lens AB; irradiate the LiNbO3:Fe photorefractive crystal, optically induce and prepare a three-dimensional photonic lattice microstructure, The convex lens A is divided into M parts. After the cutting and combining lens transformation, M is 4, which generates (4+1) plane wave interference and illuminates the photorefractive lithium niobate crystal. The size of the lithium niobate crystal is 10mm. 10mm 5mm, doped with 0.03wt% Fe, and induced a three-dimensional photonic lattice structure within the crystal.

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