Integrated vortex beam launcher

Abstract

The present invention relates to the field of vortex beam technology, and in particular to an integrated vortex beam transmitter, comprising: a laser, a straight waveguide, a ring resonator, and a composite angular grating, wherein the straight waveguide is used to receive and transmit laser light emitted by the laser; the ring resonator is coupled to the straight waveguide; a plurality of composite angular gratings, wherein the plurality of composite angular gratings are uniformly arranged in the ring resonator; each composite angular grating includes a first angular grating and a second angular grating; and the first angular grating and the second angular grating form an offset angle in the circumferential direction of the ring resonator; and the offset angle is adjusted to control the proportion of energy emitted upward by the laser to form a vortex beam of a preset order. The advantage of the present invention is that, by utilizing the offset angle formed by the first angular grating and the second angular grating of the composite angular grating in the circumferential direction of the ring resonator, the transmitter can significantly improve the efficiency of upward beam emission, even in the absence of a metal emission layer, to a maximum of 64.28%.

Description

Technical Field

[0001] The present invention relates to the technical field of vortex beams, and in particular to an integrated vortex beam emitter. Background Art

[0002] Vortex beams (VBs) and their applications have been a hot topic of research both domestically and internationally in recent years. Theoretically, VBs can be used as a new encoding method for information encoding. By combining different orders of orbital angular momentum (OAM), VBs can be used for mode division multiplexing, thereby expanding the capacity of optical communications. VBs also have a wide range of applications in information encryption, optical micromanipulation, optical tweezers, and optical spanners.

[0003] Traditional methods for generating vortex beams include mode conversion, liquid crystal spatial light modulation, spiral phase plates, holographic fork gratings, and metasurface structures. However, these methods share some common drawbacks, such as large device size, complex systems, and difficulty in integration.

[0004] With the advancement of complementary metal-oxide-semiconductor (CMOS) integration technology, an integrable vortex beam emitter has emerged in recent years. This emitter utilizes a metal mirror to control the distance between the angular grating and the reflective layer, allowing the downwardly emitted energy to be further reflected upwards and aligned with the phase of the light emitted directly upwards. Although this integrable emitter has achieved improved integration, it still faces challenges such as high manufacturing costs and an upward emission efficiency that does not exceed 50%. These issues severely limit the large-scale production and widespread application of integrated vortex beam emitters.

[0005] Therefore, how to reduce production costs and improve upward emission efficiency has become a key issue that needs to be urgently addressed in the development of integrated vortex beam launchers. Summary of the Invention

[0006] In light of this, the present invention aims to provide an integrated vortex beam emitter. By adjusting the offset angle, the emitter can control the proportion of energy emitted upward, thereby forming a vortex beam of a preset order. This emitter has high upward emission efficiency, simple processing, and high production efficiency.

[0007] To achieve the above-mentioned purpose, the technical solution created by the present invention is implemented as follows: an integrated vortex beam emitter, comprising: a laser, the laser is used to emit laser; a straight waveguide, the straight waveguide is used to receive and transmit the laser emitted by the laser; a ring resonator, the ring resonator is coupled with the straight waveguide to form a stable resonant mode; a plurality of composite angular gratings, the plurality of composite angular gratings are arranged in the ring resonator, and are uniformly distributed along the circumference of the ring resonator; each composite angular grating includes a first angular grating and a second angular grating; the first angular grating and the second angular grating are arranged at intervals along the axial direction of the ring resonator, and the first angular grating and the second angular grating form an offset angle in the circumferential direction of the ring resonator; the proportion of energy emitted upward by the composite angular grating is regulated by adjusting the offset angle to form a vortex beam of a preset order; wherein the straight waveguide, the ring resonator and the composite angular grating are integrated on the same chip.

[0008] Furthermore, the first angular grating and the second angular grating are both second-order angular gratings.

[0009] Furthermore, the ring resonator includes a first ring resonator and a second ring resonator, and the first angular grating and the second angular grating are respectively arranged in the first ring resonator and the second ring resonator.

[0010] Furthermore, a camera is included for recording the interference image of the vortex beam.

[0011] Furthermore, the region where the straight waveguide is coupled to the ring resonator is a curved structure to increase the coupling length.

[0012] Furthermore, the ring resonant cavity is in a circular ring shape, a ring racetrack shape, or an elliptical ring shape.

[0013] Furthermore, the material of the straight waveguide, the ring resonator or the composite angular grating is any one of silicon, silicon nitride, silicon oxynitride or lithium niobate.

[0014] Furthermore, the laser, the straight waveguide, the ring resonator and the composite angular grating are integrated into the same chip.

[0015] The invention can achieve the following beneficial effects:

[0016] 1) By utilizing the misaligned angles formed by the first and second angular gratings of the composite angular grating in the circumferential direction of the ring resonator, the emitter can significantly improve the efficiency of upward light emission, reaching up to 64.28%, even in the absence of a metal emission layer.

[0017] 2) By integrating the straight waveguide, ring resonator and composite angular grating on the same chip, the structure is not only small in size and simple in structure, but also can be mass-produced, thereby significantly improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 is a structural block diagram of an integrated vortex beam transmitter provided according to an embodiment of the present invention;

[0020] Figure 2 2. It is a schematic structural diagram of a straight waveguide, a ring resonator, and a composite angular grating integrated on the same chip from a first perspective according to an embodiment of the present invention;

[0021] Figure 3 2. It is a schematic structural diagram of a second perspective of a straight waveguide, a ring resonator, and a composite angular grating integrated on the same chip according to an embodiment of the present invention;

[0022] Figure 4 3. This is a schematic structural diagram of a third perspective of a straight waveguide, a ring resonator, and a composite angular grating integrated on the same chip according to an embodiment of the present invention;

[0023] Figure 5 yes Figure 2 Cross-sectional view of the composite angular grating along AA;

[0024] Figure 6 is a schematic diagram of a curved structure of a region where a straight waveguide is coupled to a ring resonator according to an embodiment of the present invention;

[0025] Figure 7 is a vortex beam diagram obtained through simulation analysis according to an embodiment of the present invention;

[0026] Figure 8 This is a proportional diagram of the upward emission efficiency of the vortex beam under different misalignment angle conditions obtained through simulation analysis according to an embodiment of the present invention.

[0027] The reference numerals include: 1. laser; 2. straight waveguide; 3. ring resonator; 4. composite angular grating; 41. first angular grating; 42. second angular grating; 5. camera. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] The present invention will be described in detail below with reference to the embodiments.

[0033] like Figures 1 to 6 As shown, an embodiment of the present invention provides an integrated vortex beam emitter, comprising: a laser 1, a straight waveguide 2, a ring resonator 3, a plurality of composite angular gratings 4, and a camera 5. The laser 1 is used to emit laser light. The straight waveguide 2 is used to receive and transmit the laser light emitted by the laser 1. The ring resonator 3 is coupled to the straight waveguide 2 to form a stable resonant mode, and the plurality of composite angular gratings 4 are evenly arranged in the ring resonator 3. The camera 5 is used to record the interference image of the vortex beam. The straight waveguide 2, the ring resonator 3, and the composite angular grating 4 are integrated on the same chip.

[0034] The laser 1 is a spatial laser, a fiber laser, or an on-chip laser. In this embodiment, the laser 1 is an on-chip laser, which is integrated with the straight waveguide 2, the ring resonator 3, and the composite angular grating 4 on the same chip.

[0035] The coupling region between the straight waveguide 2 and the ring resonator 3 is designed with a curved structure to increase the coupling length. It should be noted that this curved structure is a mature process in this field and will not be described in detail here.

[0036] The ring resonator 3 includes a first ring resonator and a second ring resonator. The ring resonator 3 is in the shape of a circular ring, a racetrack ring, or an elliptical ring.

[0037] Ring-type resonant cavity: It has high mode symmetry, supports high Q value (quality factor) resonance, and has uniform light field distribution, suitable for applications such as narrow linewidth filtering.

[0038] Annular racetrack resonant cavity: The coupling region adopts a straight structure, which allows flexible adjustment of the coupling length to improve efficiency. At the same time, the free spectral range (FSR) can be optimized by adjusting the straight side length.

[0039] Elliptical ring resonator: The resonant wavelength can be controlled by adjusting the ratio of the major and minor axes, and its asymmetric structure helps to suppress high-order mode oscillations in the laser resonator.

[0040] The number n of the composite angular gratings 4 is 30 to 300. Each composite angular grating 4 includes a first angular grating 41 and a second angular grating 42. The first angular grating 41 is arranged in the first ring resonator, and the second angular grating 42 is arranged in the second ring resonator. The first angular grating 41 and the second angular grating 42 are arranged at intervals along the axial direction of the ring resonator, and the first angular grating 41 and the second angular grating 42 form a staggered angle in the circumferential direction of the ring resonator. By adjusting the staggered angle, the proportion of energy emitted upward by the laser 1 is regulated to form a vortex beam of a preset order. The calculation formula of the staggered angle is:

[0041] ;in, is the stagger angle, duty is the duty cycle, typically duty = 0.5, and n is the number of composite angular gratings 4. The optimal stagger angle is obtained by simulation (commonly used methods: time-domain effective difference method, finite element method).

[0042] In this embodiment, the first angular grating 41 and the second angular grating 42 are both second-order angular gratings. The size of the first angular grating 41 is λ1, which is 20 nm to 20 μm; the size of the second angular grating 42 is λ2, which is 20 nm to 20 μm.

[0043] In this embodiment, the material of the straight waveguide 2, the ring resonator 3, and the composite angular grating 4 is any one of silicon, silicon nitride, silicon oxynitride, or lithium niobate. The materials of the straight waveguide 2, the ring resonator 3, and the composite angular grating 4 can be the same material or different materials.

[0044] When the straight waveguide 2, the ring resonator 3 and the composite angular grating 4 are made of silicon, silicon nitride or silicon oxynitride, the substrate of the integrated vortex beam emitter is silicon dioxide.

[0045] However, when the straight waveguide 2, the ring resonator 3 and the composite angular grating 4 are made of lithium niobate, the substrate of the integrated vortex beam emitter is a lithium niobate film.

[0046] In some special processes, a multi-layer substrate structure can be used, such as lithium niobate film / silicon dioxide / lithium niobate substrate. Alternatively, a silicon dioxide cladding layer can be deposited on the lithium niobate film to optimize optical performance.

[0047] In another embodiment, the material of the straight waveguide 2 and the composite angular grating 4 is any one of lithium niobate, indium phosphide (InP), and a polymer material.

[0048] The integrated vortex beam emitter of the present invention was simulated and analyzed using the finite-difference time-domain (FDTD) simulation software. For incident light of different wavelengths, the far-field phase of the device was tested to obtain a vortex beam. Figure 7 As shown:

[0049] Figure 7 Panel (a) shows the spectral distribution of vortex beams with different topological charges l under fixed duty cycle (duty = 0.5) and gap (gap = 0.09). The horizontal axis represents wavelength λ (in micrometers), and the vertical axis represents spectral intensity. Peaks of topological charge l are marked in the figure, corresponding to vortex beams of different orders. For example, a vortex beam with a topological charge of -2 is generated at a wavelength λ of 1.58 μm, while a vortex beam with a topological charge of -3 is generated at a wavelength λ of 1.56 μm.

[0050] Figure 7 (b), (c), (d), and (e) show the cross-sectional intensity distribution of vortex beams with different topological charges l. The number of rotating fringes in each figure represents the order of the topological charge. Figure 7 (b) shows five counterclockwise rotating stripes, representing a vortex beam with topological charge l=-5. Figure 7 (c) in the figure shows four counterclockwise rotating stripes, representing a vortex beam with a topological charge of l=-4. Figure 7 (d) shows three counterclockwise rotating stripes, representing a vortex beam with topological charge l=-3. Figure 7Figure (e) shows two counterclockwise-rotating fringes, representing a vortex beam with a topological charge of -2. These figures demonstrate the spatial distribution characteristics of vortex beams at different orders. As the topological charge increases, the number of phase rings surrounding the central singularity of the vortex beam increases. This demonstrates that an integrated vortex beam generator can generate a beam with a spiral phase, i.e., a vortex beam.

[0051] In order to illustrate that the structure of the present invention improves the efficiency of the upward emission of the light beam, we calculated the proportion of the upward emission energy of the vortex light beam generated by the composite angular grating 4 to the total emission energy. By designing simulation structures with different offset angles, the offset angles are: [0°, 0.7°, 1.4°, 2.1°, 2.8°, 3.5°, 4.2°, 4.9°]. The simulation results are shown in Figure 2. Figure 8 As shown:

[0052] Figure 8 (a) shows the different misalignment angles under fixed duty cycle (duty=0.5) and gap (gap=0.09) conditions. Figure 2 shows the upward emission efficiency of a vortex beam as a function of wavelength λ. As can be seen in the figure, the peak position and shape of the upward emission efficiency change as the misalignment angle increases. This indicates that the misalignment angle has a significant effect on the emission characteristics of the beam.

[0053] Figure 8 Panel (b) shows the average upward emission efficiency of the vortex beam at different offset angles, with a wavelength of 1.55 μm and the same duty cycle and gap conditions. The figure displays the upward emission efficiency of the vortex beam at different offset angles in the form of a bar chart. It can be seen that when the offset angle is 2.8°, the upward emission efficiency reaches a maximum of 64.28%. This shows that the upward emission efficiency of the vortex beam can be significantly improved at a specific offset angle.

[0054] Figure 8 The two figures show that by adjusting the stagger angle, the upward emission efficiency of the vortex beam can be effectively improved.

[0055] In addition, the upward emission efficiency of the vortex light beam can be further improved by optimizing the size of the first angular grating 41 and the size and offset angle of the second angular grating 42.

[0056] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. An integrated vortex beam transmitter, characterized in that: include: a laser, wherein the laser is used to emit laser light; a straight waveguide, the straight waveguide being used to receive and transmit the laser light emitted by the laser; a ring resonant cavity, wherein the ring resonant cavity is coupled with the straight waveguide to form a stable resonant mode; A plurality of composite angular gratings are provided in the annular resonator and uniformly distributed along the circumference of the annular resonator; each composite angular grating includes a first angular grating and a second angular grating; the first angular grating and the second angular grating are spaced apart along the axial direction of the annular resonator, and the first angular grating and the second angular grating form an offset angle in the circumferential direction of the annular resonator; the offset angle is adjusted to control the proportion of energy emitted upward by the composite angular grating to form a vortex beam of a preset order; The straight waveguide, the ring resonant cavity and the plurality of composite angular gratings are integrated on the same chip.

2. The integrated vortex beam emitter according to claim 1, characterized in that: The first angular grating and the second angular grating are both second-order angular gratings.

3. The integrated vortex beam transmitter according to claim 1, characterized in that: The ring resonator includes a first ring resonator and a second ring resonator. The first angular grating and the second angular grating are respectively arranged in the first ring resonator and the second ring resonator.

4. The integrated vortex beam emitter according to claim 1, characterized in that: A camera is also included to record the interference image of the vortex beam.

5. The integrated vortex beam emitter according to claim 1, characterized in that: The region where the straight waveguide is coupled to the ring resonant cavity is a curved structure to increase the coupling length.

6. The integrated vortex beam transmitter according to claim 1, characterized in that: The ring resonant cavity is in a circular ring shape, a ring racetrack shape, or an elliptical ring shape.

7. The integrated vortex beam transmitter according to claim 1, characterized in that: The material of the straight waveguide, the ring resonant cavity or the composite angular grating is any one of silicon, silicon nitride, silicon oxynitride or lithium niobate.

8. The integrated vortex beam transmitter according to claim 1, characterized in that: The laser, the straight waveguide, the ring resonator and the composite angular grating are integrated into the same chip.

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