A system of tilted waveguide arrays for beam refraction, a control device and a control method

Abstract

The application discloses a kind of for light beam refraction, slanted waveguide array system, regulation and control device and regulation and control method, belong to micro-nano optical technology field.A kind of for light beam refraction, slanted waveguide array system includes: substrate and slanted waveguide array;The slanted waveguide array includes first slanted waveguide array and second slanted waveguide array cascaded in head and tail;Substrate is located below slanted waveguide array;First slanted waveguide array and second slanted waveguide array are all rotated preset angle along array extension direction, after rotation, not collinear, preset angle range is 0-30 degrees;Incident light occurs refraction when passing the interface of first slanted waveguide array and second slanted waveguide array.Based on system band structure, the initial bloch wave vector corresponding to different refraction effects is determined, and the initial incidence angle of light beam is calculated;Adjust the incidence direction of incident light, different refraction effects will occur to light beam at interface, to realize the accurate regulation and control of discrete light beam refraction effect.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano optics technology, and more specifically, relates to a tilted waveguide array system, control device, and control method for beam refraction. Background Technology

[0002] Refraction is a fundamental optical phenomenon that occurs when a beam of light travels through an interface between two media with different refractive indices or through a non-uniform medium. The refraction effect has wide applications in many fields, such as photonic neural networks, quantitative phase microscopy, and optical information processing. Therefore, in-depth research and precise control of the concept of refraction are of great significance in geometrical optics, wave optics, and quantum optics. With the introduction of new concepts such as topological photonics and non-Hermitian physics in recent years, research on refraction has expanded beyond traditional continuous media to include discrete optical systems in order to explore deeper laws and effects of refraction. By rationally designing the structure and parameters of discrete systems, anomalous refraction phenomena that cannot be supported in continuous media can be achieved, thereby expanding the theoretical mechanisms and application scope of refraction.

[0003] For discrete optical systems, researchers have achieved manipulation of refraction effects by adding a moving potential barrier to a spatial waveguide array (S. Longhi, Opt. Lett. 42, 3229-3232 (2017)). By adjusting the speed of the moving potential barrier region, the refraction effect of the beam at the interface can be controlled. In addition, the refraction system has been extended from real space to the photon synthesis dimension (H. Ye, at al., Proc. Natl. Acad. Sci. 120, e2300860120 (2023)). The refraction of the synthesized beam in the time dimension was achieved by using phase modulation of a coupled dual-fiber loop. However, the former is difficult to achieve experimentally because it requires repeated fabrication of waveguide arrays to achieve different refraction effects and the material deposition steps in the barrier region are complex. The latter, due to the special architecture of the dual-fiber loop experimental system, requires subsequent data processing to observe the refraction effect.

[0004] Therefore, existing discrete optical systems for controlling beam refraction effects suffer from technical problems such as complex structure, difficult manufacturing process, and inconvenient observation. Summary of the Invention

[0005] In view of the shortcomings of related technologies, the purpose of this invention is to provide a tilted waveguide array system, control device and control method for beam refraction, which aims to solve the technical problems of complex structure, difficult manufacturing process and inconvenient observation in existing discrete optical systems for controlling beam refraction effects.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a tilted waveguide array system for beam refraction, comprising: a substrate and a tilted waveguide array; the tilted waveguide array includes a first tilted waveguide array and a second tilted waveguide array cascaded end-to-end;

[0007] The substrate is located below the first and second tilted waveguide arrays and is used to constrain the transmission of the beam in the waveguide arrays.

[0008] Both the first tilted waveguide array and the second tilted waveguide array are rotated by a preset angle along the array extension direction, and the preset angle ranges from 0 to 30 degrees; the first tilted waveguide array and the second tilted waveguide array are not collinear;

[0009] The incident light is refracted when it passes through the interface between the first tilted waveguide array and the second tilted waveguide array.

[0010] Optionally, the first tilted waveguide array and the second tilted waveguide array rotate in opposite directions, and the first tilted waveguide array and the second tilted waveguide array rotate at the same preset angle.

[0011] Optionally, the first tilted waveguide array and the second tilted waveguide array rotate in the same direction, but the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are different.

[0012] Optionally, the preset angle θ between the first tilted waveguide array and the second tilted waveguide array satisfies v = tan(θ); where z is the extension direction of the vertical waveguide array, and v is the slope of the waveguide in the z direction, representing the degree of tilt of the waveguide.

[0013] Optionally, the waveguide material of the first tilted waveguide array and the second tilted waveguide array is a polymer with a refractive index between 1.5 and 3.8, and the substrate material is silicon dioxide.

[0014] In a second aspect, the present invention also provides a control device for beam refraction, comprising: a light source, a coupling lens, a microscope, a CCD detector, a controller, and a tilted waveguide array system for beam refraction as described in any one of the first aspects.

[0015] The light source, coupling lens, tilted waveguide array system, microscope and CCD detector are arranged sequentially along the optical path;

[0016] The light source is used to generate incident light;

[0017] The coupling lens is used to change the beam coupling direction of the incident light to control the initial incident angle of the incident light, so that the incident light is coupled to the incident end face of the waveguide array at the incident angle corresponding to the desired refraction effect type.

[0018] The tilted waveguide array system is used to transmit incoming light, causing it to refract at the interface between the two waveguide arrays and then exit.

[0019] The microscope is used to magnify and transmit the light beam emitted from the tilted waveguide array system to the CCD detector.

[0020] The CCD detector is used to collect the intensity and position of the light beam emitted from the microscope;

[0021] The controller is connected to the coupling lens and the CCD detector, and is used to determine whether the type of refraction effect meets the requirements based on the intensity of the beam collected by the CCD detector and the exit position. If it does not meet the requirements, the controller controls the coupling lens to adjust the initial incident angle of the incident light.

[0022] Thirdly, the present invention also provides a method for controlling beam refraction, applied in the beam refraction control device described in the second aspect, comprising:

[0023] S1. Determine the magnitude and direction of the group velocity of the incident light in the corresponding region based on the different band structures in the tilted waveguide array system;

[0024] S2. Based on the magnitude and direction of the group velocity of the incident light, determine the initial Bloch wave vector corresponding to the required type of refraction effect;

[0025] S3. Calculate the initial incident angle of the beam based on the conversion relationship between the Bloch wave vector and the incident angle.

[0026] S4. Based on the initial incident angle, adjust the incident angle of the incident light so that the incident light undergoes a refraction effect at the interface between the first tilted waveguide array and the second tilted waveguide array.

[0027] Optionally, following S4, the following also includes:

[0028] S5. The controller collects the beam intensity and exit position through the CCD detector, and compares the waveguide position corresponding to the exit position with the waveguide position corresponding to the incident beam to determine whether the type of refraction effect of the beam in the waveguide array system meets the requirements. If it does not meet the requirements, S6 is executed; if it meets the requirements, the process ends.

[0029] S6. Control the coupling lens to adjust the beam coupling direction, adjust and update the initial incident angle of the incident light, and return to S4.

[0030] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0031] 1. The present invention provides a tilted waveguide array system for beam refraction, which establishes a concept of adding vector potential and scalar potential to the beam by tilting the waveguide array. Based on the reference frame transformation theory, the band structure of the beam in different regions is obtained. The band structure is adjusted by changing the tilt of the array in different regions in a relatively intuitive and simple way. The incident angle of the beam is determined by band matching, thereby achieving precise control of the refraction effect type.

[0032] 2. The present invention provides a tilted waveguide array system for beam refraction. The waveguide array material is a homogeneous medium. It does not require changing the refractive index of the material in some areas of the waveguide array. The beam refraction is achieved by using two waveguide arrays with different tilt angles or tilt directions. Therefore, it is easy to prepare a high-precision experimental system using existing technical means.

[0033] 3. The tilted waveguide array system for beam refraction provided by this invention is applicable to a spatial waveguide array in real space. The angle of incident light is not limited by the experimental system and can be incident at any angle. Therefore, the range of adjustable refraction effect is wider. In addition, the beam refraction process can be observed intuitively through the discrete beam refraction effect control device provided by this invention, and the type of refraction effect can be precisely controlled through the discrete beam refraction effect control method provided by this invention. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a tilted waveguide array system for beam refraction provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of another tilted waveguide array system for beam refraction provided in an embodiment of the present invention, wherein (a) is a schematic diagram of the tilted waveguide array system, (b) is the band structure curve of the two regions, (c) is the group velocity relationship curve of the two regions, and (d), (e), and (f) are the light field evolution diagrams for negative refraction, vertical propagation, and positive refraction, respectively.

[0036] Figure 3 This is a schematic diagram of another tilted waveguide array system for beam refraction provided by an embodiment of the present invention, wherein (a) is a schematic diagram of the tilted waveguide array system, (b) is the band structure curve of the two regions, (c) is the group velocity relationship curve of the two regions, and (d), (e) and (f) are the light field evolution diagrams for negative refraction, vertical transmission and positive refraction, respectively.

[0037] Figure 4This is a schematic diagram of a beam refraction control device provided in an embodiment of the present invention, wherein (a) is a tilted waveguide array system in which the first tilted waveguide array and the second tilted waveguide array rotate in opposite directions and the first tilted waveguide array and the second tilted waveguide array rotate at the same preset angle; and (b) is a tilted waveguide array system in which the first tilted waveguide array and the second tilted waveguide array rotate in the same direction and the first tilted waveguide array and the second tilted waveguide array rotate at different preset angles.

[0038] Figure 5 This is a flowchart of a method for controlling beam refraction provided in an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of another tilted waveguide array system for beam refraction provided in an embodiment of the present invention, wherein (a) is a schematic diagram of the tilted waveguide array system, (b) is the band structure curve of the two regions, (c) is the group velocity relationship curve of the two regions, (d) is the evolution diagram when the beam is perpendicularly incident, (e) is the evolution diagram of one type of beam transmission without refraction, and (f) is the evolution diagram of another type of beam transmission without refraction. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0041] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0042] To address the technical problems of complex structure, difficult manufacturing process, and inconvenient observation in existing discrete optical systems for controlling beam refraction effects, this invention provides a discrete optical system that is simple in structure, easy to manufacture, and easy to observe.

[0043] Before explaining the technical solution of the present invention in detail, the relevant technical terms are briefly introduced as follows:

[0044] Laboratory reference frame: In this invention, the laboratory reference frame refers to a reference frame that is stationary relative to the ground, with coordinate axes x and z.

[0045] Moving reference frame: In this invention, a moving reference frame refers to a reference frame that moves relative to the laboratory reference frame, with coordinate axes x', z'.

[0046] like Figure 1As shown, the present invention provides a tilted waveguide array system for beam refraction, comprising: a substrate and a tilted waveguide array; the tilted waveguide array includes a first tilted waveguide array and a second tilted waveguide array cascaded end-to-end;

[0047] The substrate is located below the first and second tilted waveguide arrays and is used to constrain the transmission of the beam in the waveguide arrays.

[0048] Both the first tilted waveguide array and the second tilted waveguide array are rotated by a preset angle along the array extension direction, and the preset angle ranges from 0 to 30 degrees; the first tilted waveguide array and the second tilted waveguide array are not collinear;

[0049] The incident light is refracted when it passes through the interface between the first tilted waveguide array and the second tilted waveguide array.

[0050] The waveguide materials of the first and second tilted waveguide arrays are polymers with a refractive index between 1.5 and 3.8. In this embodiment of the invention, the waveguide material of the tilted waveguide array is a polymer with a refractive index of 1.554 under 632.8 nm incident light, and the substrate material is silicon dioxide.

[0051] By changing the preset angles of the first and second tilted waveguide arrays, the type of beam refraction effect can be controlled.

[0052] In the above-mentioned tilted waveguide array system, the combination of the first tilted waveguide array and the second tilted waveguide array includes three cases: (1) the first tilted waveguide array and the second tilted waveguide array rotate in opposite directions, and the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are the same. (2) the first tilted waveguide array and the second tilted waveguide array rotate in the same direction, but the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are different. (3) the first tilted waveguide array and the second tilted waveguide array rotate in opposite directions, but the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are different. In this application, cases (1) and (2) are used as examples for illustration. Case (1) is as follows: Figure 2 As shown in (a), case (2) is as follows Figure 3 As shown in (a).

[0053] The tilted waveguide array is obtained by tilting a vertical coupled waveguide array to the left or right at a certain angle while maintaining the incident end face as the plane containing the x-axis. In essence, it is a reference frame transformation of the vertical waveguide array as follows: (x,z)→(x',z'), and the transformation relationship is expressed as: x'=x±vz, z'=z; where x is the arrangement direction of the vertical waveguide array, z is the extension direction of the vertical waveguide array, v is the slope of the waveguide in the z direction, indicating the degree of tilt of the waveguide, the "±" sign represents the direction of tilt of the waveguide array, "+" represents the waveguide array tilting to the left, and "-" represents the waveguide array tilting to the right; the preset angle θ of rotation between the first tilted waveguide array and the second tilted waveguide array satisfies v=tan(θ).

[0054] In this embodiment, the principle of controlling the refraction effect of discrete beams is as follows:

[0055] The beam in the vertical waveguide array satisfies the following paraxial approximate wave equation:

[0056]

[0057] Where ψ(x,z) is the electric field envelope, n0 is the refractive index of the waveguide material, k0=n0(2π / λ) is the wave number in the medium, λ is the vacuum wavelength, and Δn(x,z) represents the refractive index distribution of the tilted waveguide array.

[0058] Substituting the above coordinate transformation relationship into equation (1), we can obtain the light field evolution equation of the array tilted to the right in the moving reference frame:

[0059]

[0060] As can be seen from the above equation, after coordinate transformation, the equation includes a vector potential term A = vk0 and a scalar potential term. This demonstrates that array tilting can introduce an equivalent gauge potential, allowing the beam to be subjected to a potential field without changing the refractive index of the array material. Applying the tight-binding approximation and nearest-neighbor approximation to equation (2), it can be rewritten as the discrete coupled-wave equation in a moving reference frame:

[0061]

[0062] Where c is the coupling coefficient between two adjacent waveguides, and a is the array lattice constant. To facilitate band structure analysis, equation (3) is transformed into the coupled wave equation of the tilted array in the laboratory reference frame by the inverse Galilean transformation: z = z', n = n' + vz'.

[0063]

[0064] The eigenBloch mode of the waveguide array |φ>=e ikn e-iβz Substituting into the above equation, we obtain the band structure of the right-tilted array as: β1 = -2ccos(ka - k0va) + vk. Similarly, we can obtain the band structure of the left-tilted array as: β2 = -2ccos(ka + k0va) - vk. Taking the first-order differential of the above two equations with respect to the Bloch wave vector k, we can obtain the group velocity v of the beam in the two tilted arrays. g1 =2casin(ka-k0va)+v and v g2 =2casin(ka+k0va)-v.

[0065] Connecting two arrays with different tilt directions or angles, but identical other characteristic parameters, end-to-end along the waveguide extension direction constitutes a tilted waveguide array system. The interface between the two arrays is the interface where the refraction effect occurs. Since the interface is horizontal, according to Snell's law, the transverse Bloch wave vector k is conserved in both regions. Because the group velocity magnitude and direction of the beam propagation in the two arrays can be determined from the Bloch wave vector corresponding to different incident angles in different tilted waveguide arrays, and further, the initial incident angle can be calculated based on the desired type of refraction effect. Specifically, if the group velocities of the beam in the two arrays have the same sign, it indicates positive refraction at the interface; if the group velocities have opposite signs, it indicates negative refraction at the interface; if the group velocity of the beam is zero in a certain region, it indicates that the beam propagates perpendicularly in that region. Using plotting software to draw the group velocity curve, the relationship between the group velocities in the two regions can be visually obtained, allowing for the selection of an appropriate initial Bloch wave vector based on the expected refraction type, thus achieving precise control over the refraction type of the discrete beam.

[0066] This invention provides a tilted waveguide array system for beam refraction. The waveguide array material is a homogeneous medium, eliminating the need to change the refractive index of certain regions of the waveguide array. Beam refraction is achieved solely through two waveguide arrays with different tilt angles or directions. Furthermore, the band structure is adjusted in a relatively intuitive and simple way by changing the tilt degree of different regions of the array. This further determines the Bloch wave vector intervals corresponding to different refraction effects, thereby changing the incident angle of the beam and achieving the goal of precisely controlling the type of refraction effect.

[0067] Based on the above embodiments, in order to achieve precise control of the discrete beam refraction effect, another embodiment also provides a beam refraction control device, such as... Figure 4 As shown, it includes: a light source, a coupling lens, a microscope, a CCD detector, a controller, and a tilted waveguide array system for beam refraction as described in the above embodiments;

[0068] The light source, coupling lens, tilted waveguide array system, microscope and CCD detector are arranged sequentially along the optical path;

[0069] The light source is used to generate incident light;

[0070] The coupling lens is used to change the beam coupling direction of the incident light to control the initial incident angle of the incident light, so that the incident light is coupled to the incident end face of the waveguide array at the incident angle corresponding to the desired refraction effect type.

[0071] The tilted waveguide array system is used to transmit incoming light, causing it to refract at the interface between the two waveguide arrays and then exit.

[0072] The microscope is used to magnify and transmit the light beam emitted from the tilted waveguide array system to the CCD detector.

[0073] The CCD detector is used to collect the intensity and position of the light beam emitted from the microscope;

[0074] The controller is connected to the coupling lens and the CCD detector, and is used to determine whether the type of refraction effect meets the requirements based on the intensity of the beam collected by the CCD detector and the exit position. If it does not meet the requirements, the controller controls the coupling lens to adjust the initial incident angle of the incident light.

[0075] in, Figure 4 (a) and (b) are schematic diagrams of waveguide array systems with opposite and the same tilt direction, respectively.

[0076] The light source emits a continuous laser beam with a wavelength of 632.8 nm. A coupling lens is placed behind the emitted laser beam to focus the light onto the waveguide array end face. Changing the position of the coupling lens adjusts the incident angle of the beam. A microscope receives the beam emitted from the system and magnifies it to a suitable size. A CCD detector collects the intensity of the beam emitted from the microscope.

[0077] The principle by which the control device in this embodiment verifies the refraction effect of discrete beams is as follows:

[0078] By adjusting the incident position of the beam on the array end face through the coupling lens, the number of waveguide elements where the pulse center is located is determined. After the beam exits through the waveguide array system, the waveguide position where the center of the exit beam is located is extracted on the CCD detector. Based on the incident and exit positions of the beam, the type of refraction effect that occurs at the interface is determined.

[0079] This invention establishes a concept of adding vector and scalar potentials to a light beam by tilting a waveguide array, and adjusts the band structure in a relatively intuitive and simple way by changing the tilt degree of different regions of the array. The entire waveguide array of this invention is made of a homogeneous medium, simplifying the manufacturing process. Furthermore, because this invention is a real-space system, the adjustment range of the beam incident angle is wide. Therefore, this invention is a method for precisely controlling the refraction effect type of discrete light beams.

[0080] Based on the above embodiments, in order to achieve precise control of the refraction effect of discrete beams through the control device, another embodiment provides a method for controlling beam refraction, such as... Figure 5 As shown, it includes the following steps:

[0081] S1. Determine the magnitude and direction of the group velocity of the incident light in the corresponding region based on the different band structures in the tilted waveguide array system;

[0082] S2. Based on the magnitude and direction of the group velocity of the incident light, determine the initial Bloch wave vector corresponding to the required type of refraction effect;

[0083] S3. Calculate the initial incident angle of the beam based on the conversion relationship between the Bloch wave vector and the incident angle.

[0084] S4. Adjust the incident angle of the incident light to the initial incident angle so that the incident light undergoes a refraction effect at the interface between the first tilted waveguide array and the second tilted waveguide array.

[0085] When the required type of refraction effect is different, the coupling lens is adjusted to adjust the beam coupling direction according to the corresponding calculated initial incident angle, so as to adjust the initial incident angle of the incident light, thereby adjusting the type of refraction effect of the beam in the tilted waveguide array system.

[0086] Based on the above embodiments, optionally, after S4, the following step is also included:

[0087] S5. The controller collects the beam intensity and exit position through the CCD detector, and compares the waveguide position corresponding to the exit position with the waveguide position corresponding to the incident beam to determine whether the type of refraction effect of the beam in the waveguide array system meets the requirements. If it does not meet the requirements, S6 is executed; if it meets the requirements, the process ends.

[0088] S6. Control the coupling lens to adjust the beam coupling direction, adjust and update the initial incident angle of the incident light, and return to S4.

[0089] If the beam intensity and exit position of the emitted light obtained by the CDD detector differ from the beam intensity and exit position that should be present in the required refraction type in the tilted waveguide array system, the above method steps need to be adjusted. Specifically, by comparing the waveguide position corresponding to the exit position with the waveguide position corresponding to the incident beam, it is determined whether the type of refraction effect of the beam in the waveguide array system meets the requirements; if it does not meet the requirements, the coupling lens is controlled to adjust the beam coupling direction, and the initial incident angle of the incident light is adjusted and updated.

[0090] The adjustment of the incident angle of the incident light includes: changing the initial incident angle of the light beam by adjusting the beam coupling direction of the coupling lens.

[0091] In one optional implementation, this embodiment uses red light with a wavelength of λ = 632.8 nm as the incident light.

[0092] In an optional implementation, this embodiment selects a polymer with a refractive index n = 1.554 as the waveguide material.

[0093] In one optional implementation, the waveguide width w = 300nm, the adjacent waveguide spacing d = 150nm, the number of waveguide elements N = 80, and the transmission distance L = 80um for each waveguide array.

[0094] In one optional implementation, this embodiment uses a Gaussian beam with a radius of 6 times the lattice length. At this radius, the waveguide array diffracts the beam less, which is beneficial for observing the beam's transmission path.

[0095] like Figure 2 As shown, as an optional implementation, this embodiment first considers a tilted waveguide array system composed of a first tilted waveguide array and a second tilted waveguide array with opposite rotation directions and the same preset rotation angle. Figure (a) shows a schematic diagram of the system structure.

[0096] In an optional implementation, the waveguide tilt is set to v = 0.1. Based on the relationship between the coupling coefficient and the coupling distance L = π / 2c, the coupling coefficient between adjacent waveguides can be calculated as c = 0.2038 μm. -1 Using the band structure formula of a beam in a tilted waveguide array, the band structure and group velocity relationship curves in the two regions can be further plotted, as shown in (b) and (c), where ka represents the Bloch momentum of the system.

[0097] From the group velocity curves, it can be seen that when the Bloch momentum ka = 0, the group velocities of the beam in the two arrays are exactly opposite in sign and equal in magnitude. This indicates that the beam undergoes a negative refraction effect at the interface, and the degree of deflection is the same in both regions. At this point, the beam enters the waveguide array perpendicularly and undergoes refraction at the interface. The evolution of the beam in the system under these conditions was simulated using COMSOL Multiphysics software, and the results are as follows... Figure 2 As shown in Figure (d), it can be seen that negative refraction occurs at the interface, which is consistent with the theoretical analysis. Numerical calculations show that when the Bloch momentum ka = 0.041π, the group velocity of the beam in the left-tilted waveguide array is 0, indicating that the beam propagates vertically in the array. The initial incident angle of the beam at this time is 0.03°. Figure (e) shows the evolution trajectory of the beam in the system with this incident angle, showing that the beam propagates vertically in the second tilted waveguide array. When ka = π / 2, the group velocities in both regions are positive, and the group velocity in the right-tilted array is greater than that in the left-tilted array, indicating that positive refraction occurs at the interface. The refraction path is similar to that of light entering an optically denser medium from an optically less dense medium in a continuous medium. The initial incident angle of the beam at this time is calculated to be 36°. When the beam is incident into the system at this angle, the evolution path of the beam is shown in Figure (f), showing that positive refraction occurs at the interface. The above results are obtained through numerical calculations and software simulations. In actual experimental operations, a CCD detector needs to be used to obtain the beam intensity and exit position of the emitted light, and then compared with the beam intensity and exit position of the incident light to determine the type of refraction effect of the beam. In summary, this embodiment performs all operations according to the control method, and by adjusting the incident angle of the beam, the refraction effect of the discrete beam is controlled.

[0098] As an optional implementation, this embodiment further considers a tilted waveguide array system in which the first tilted waveguide array and the second tilted waveguide array rotate in the same direction, but the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are different.

[0099] like Figure 3 As shown, in an optional implementation, the tilt angles of the two right-tilted waveguide arrays are set from bottom to top as v1 = 0.1 and v2 = 0.2, respectively, resulting in the system structure shown in Figure (a). Based on the formula and simulation results, the coupling coefficient c1 in the two arrays can be obtained as 0.2038 μm. -1 c2 = 0.2148um -1Thus, the band structure and group velocity relationship curves are plotted, as shown in (b) and (c). Analysis of the images reveals that the group velocity values ​​in the two regions are both positive and negative, and under the same Bloch momentum, there are cases with opposite signs, indicating that negative refraction, perpendicular transmission, and positive refraction can also be achieved in this system. Based on the read image information and numerical calculations, it is found that negative refraction, perpendicular transmission, and positive refraction effects can be generated in the system when the Bloch momentum ka = -π / 2, -0.041π, and π / 4. Figures (d), (e), and (f) respectively show the light field evolution trajectories simulated by software under the above conditions, which are consistent with the analysis results, indicating that the refraction effect of discrete beams has been controlled in this embodiment.

[0100] In addition to precisely controlling the refraction effect of the beam, this system can also achieve refractionless beam transmission. For example... Figure 6 As shown, in an optional implementation, the tilt angles of the two right-tilted waveguide arrays are set from bottom to top as v1 = 0.3 and v2 = 0.4. The system structure is shown in Figure (a), and the coupling coefficient between adjacent waveguides in the two regions is c1 = 0.2392 μm. -1 c2 = 0.2748um -1 Figures (b) and (c) show the band structure and group velocity relationship curves of the system plotted based on the above parameters. It is clear from the figures that the group velocities of both arrays are positive within the given momentum range, indicating that regardless of the initial Bloch wave vector, the beam undergoes positive refraction at the interface. Figure (d) shows the optical field evolution corresponding to Bloch momentum ka = 0, which conforms to the corresponding information. Furthermore, the group velocity curves intersect at two points, indicating that under this Bloch momentum, the group velocity of the beam is the same in both regions, meaning that the beam's propagation direction does not change after passing through the interface. Numerical calculations show that the Bloch momentum corresponding to the two intersection points is ka = 0.29π and ka = 0.52π. Figures (e) and (f) respectively show the beam propagation paths under the above conditions, showing that both are non-refractive propagation, consistent with the theoretical analysis, indicating that non-refractive propagation of discrete beams is achieved in this embodiment.

[0101] Specifically, in the above embodiment, the relationship between the Bloch wave vector and the incident angle of the beam is: tanθ = k x / k y ,in

[0102] This invention provides a method for controlling the refraction effect of discrete light beams, applied to a control device including a tilted waveguide array system. In this system, two arrays with different tilt directions or angles but identical other characteristic parameters are connected end-to-end along the waveguide extension direction. The interface between the two arrays is the interface where the refraction effect occurs. The group velocity magnitude and direction of the beam propagation in the two arrays are obtained based on the Bloch wave vector corresponding to different incident angles, thereby further determining the type of refraction effect. An initial incident angle is set according to the desired type of refraction effect. The waveguide position corresponding to the outgoing beam position obtained by the CCD detector is compared with the waveguide position corresponding to the incident beam to determine whether the type of refraction effect occurring in the waveguide array system matches the expectation. If not, the beam coupling direction of the coupling lens is adjusted to change the initial incident angle, thereby changing the actual type of refraction effect and achieving the desired refraction effect. This method solves the technical problems of complex structure, difficult manufacturing process, and inconvenient observation in existing discrete optical systems for controlling beam refraction effects, achieving the beneficial effect of precise control of discrete light beam refraction effects.

[0103] Those skilled in the art will readily understand that the above description is merely 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 within the scope of protection of the present invention.

Claims

1. A method for controlling beam refraction, using a tilted waveguide array system for beam refraction, the tilted waveguide array system comprising: Substrate and tilted waveguide array; the tilted waveguide array includes a first tilted waveguide array and a second tilted waveguide array cascaded end-to-end; The substrate is located below the first and second tilted waveguide arrays and is used to constrain the transmission of the beam in the waveguide arrays; both the first and second tilted waveguide arrays are rotated by a preset angle along the array extension direction, and the preset angle ranges from 0 to 30 degrees; the first and second tilted waveguide arrays are not collinear. The incident light is refracted at the interface between the first tilted waveguide array and the second tilted waveguide array; characterized in that the modulation method includes: S1. Determine the magnitude and direction of the group velocity of the incident light in the corresponding region based on the different band structures in the tilted waveguide array system; S2. Based on the magnitude and direction of the group velocity of the incident light, determine the initial Bloch wave vector corresponding to the required type of refraction effect; S3. Calculate the initial incident angle of the beam based on the conversion relationship between the Bloch wave vector and the incident angle. S4. Adjust the incident angle of the incident light to the initial incident angle so that the incident light undergoes a refraction effect at the interface between the first tilted waveguide array and the second tilted waveguide array.

2. The control method as described in claim 1, characterized in that, The first tilted waveguide array and the second tilted waveguide array rotate in opposite directions, and the first tilted waveguide array and the second tilted waveguide array rotate at the same preset angle.

3. The control method as described in claim 1, characterized in that, The first tilted waveguide array and the second tilted waveguide array rotate in the same direction, but the preset angles of rotation of the first tilted waveguide array and the second tilted waveguide array are different.

4. The control method as described in any one of claims 2 or 3, characterized in that, The first tilted waveguide array and the second tilted waveguide array rotate at a preset angle θ satisfy v =tan( θ );in, z This represents the extension direction of the vertical waveguide array. v For waveguides in z The slope in the direction indicates the degree of tilt of the waveguide.

5. The control method as described in claim 1, characterized in that, The waveguide material of the first tilted waveguide array and the second tilted waveguide array is a polymer with a refractive index between 1.5 and 3.8, and the substrate material is silicon dioxide.

6. The control method as described in claim 1, characterized in that, Following S4, it also includes: S5. Collect the beam intensity and exit position, and compare the waveguide position corresponding to the exit position with the waveguide position corresponding to the incident beam to determine whether the type of refraction effect of the beam in the waveguide array system meets the requirements. If it does not meet the requirements, proceed to S6. If it meets the requirements, end. S6. Adjust the beam coupling direction to control and update the initial incident angle of the incident light, and return to S4.

7. A control device for beam refraction, characterized in that, include: Light source, coupling lens, microscope, CCD detector, controller; The light source, coupling lens, tilted waveguide array system, microscope and CCD detector are arranged sequentially along the optical path; The light source is used to generate incident light; The coupling lens is used to change the beam coupling direction of the incident light to control the initial incident angle of the incident light, so that the incident light is coupled to the incident end face of the waveguide array at the incident angle corresponding to the desired refraction effect type. The tilted waveguide array system is used to transmit incoming light, causing it to refract at the interface between the two waveguide arrays and then exit. The microscope is used to magnify and transmit the light beam emitted from the tilted waveguide array system to the CCD detector. The CCD detector is used to collect the intensity and position of the light beam emitted from the microscope; The controller is connected to the coupling lens and the CCD detector, and is used to determine whether the type of refraction effect meets the requirements based on the intensity of the beam collected by the CCD detector and the exit position. If it does not meet the requirements, the controller controls the coupling lens to adjust the initial incident angle of the incident light. The controller is used to execute the adjustment method as described in any one of claims 1-6.

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