Device and control method of a high-vacuum on-chip optical trap based on a metalens

Abstract

The present invention discloses a device and a control method for a high-vacuum on-chip optical trap based on a metalens. The present invention includes an on-chip sensing unit integrating a metalens, an optical fiber, and a microsphere storage microcavity, and a microsphere displacement detection and cooling assembly; the on-chip sensing unit is placed in a vacuum chamber to ensure that it is in a high vacuum, a laser is turned on so that after passing through the optical fiber and the metalens, a counter-propagating double-beam optical trap is formed, the vibration assembly is turned on to vibrate the microcavity so that the microsphere is desorbed and then captured by the optical trap, and the scattered light of the captured particle is collected from the side by using a detection optical fiber to realize the acquisition of the three-axis displacement signal of the particle. On this basis, a cooling laser is introduced to suppress the centroid motion of the microsphere. The present invention introduces a metalens into the fiber optical trap, greatly reducing the volume of the on-chip optical trap while improving the detection sensitivity; multiple optical fibers are introduced to realize the displacement detection and cooling of the microsphere. The high integration and high stability of the present invention solve the problems of miniaturization and on-chip integration for the practical application of a high-precision vacuum optical trap accelerometer.

Description

Technical Field

[0001] The present invention relates to a device and method for on-chip integration in the field of optically trapped suspended microspheres, and particularly to a device and method for a high-vacuum on-chip optical trap based on a metalens. Background Art

[0002] Optical tweezers is an optical technique that uses the radiation pressure of light to suspend, measure, and manipulate microspheres with sizes ranging from dozens of nanometers to dozens of micrometers, and is also known as an optical trap. Optical tweezers can be used as a microprobe to measure the tiny displacement and tiny force on the order of pN of microspheres in real time, so it has a wide application space and extremely high value in the direction of high-precision acceleration sensors. Among them, vacuum optical tweezers can isolate external thermodynamic noise and further improve the measurement accuracy.

[0003] Traditional spatial optical trap systems are large in volume and complex in optical path. In recent years, the development of micro-nano technology has promoted the development of on-chip integrated optical traps. Technologies such as fiber optical traps and cavity optical traps have emerged, making the acceleration sensing system based on optical tweezers not only have the advantages of optical measurement, but also have the characteristics of small volume, easy manufacturing, good stability, and low cost, providing great possibilities for the transformation of optical suspension technology from basic physical research to engineering technology applications. The "On-chip optical levitation with a metalens in vacuum" by the Tongcang Li group combines a metalens fabricated by micro-nano technology with a traditional spatial optical trap system and successfully suspends sub-100-nm microspheres with a single beam, but the volume of the spatial optical path is still large.

[0004] At the same time, there are still many problems to be solved on the way of the development of on-chip integrated optical traps. For example, the sensing microspheres, which are the core sensitive units, are easy to lose and difficult to repeatedly pick up and support. The low stiffness of ordinary fiber optical traps results in poor stability of the optical trap. Another example is that the self-focusing fiber optical trap of CN 110595151 B uses a fiber with a low numerical aperture (usually NA < 0.3), so the scattered efficiency of the captured microspheres to the captured light is low and the detection sensitivity is low. In addition, for acceleration sensing, the acceleration measurement accuracy increases with the increase of the microsphere mass, but large-mass microspheres are extremely easy to escape in vacuum and still need to rely on an external cooling system to help stabilize the capture and suspension. Summary of the Invention

[0005] In order to solve the problems existing in the background art, the present invention provides a device and method for a high-vacuum on-chip optical trap based on a metalens. The present invention introduces a metalens into a fiber optical trap, greatly reducing the volume of the on-chip optical trap while improving the detection sensitivity; designs a microcavity structure to store microspheres to achieve repeated pick-up and capture of microspheres; and at the same time introduces multiple optical fibers to realize microsphere displacement detection and cooling, making the on-chip sensing unit have the characteristics of high integration, high stability, and practicability.

[0006] To achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0007] I. An apparatus for a high-vacuum on-chip optical trap based on a metasurface

[0008] The apparatus includes a vacuum chamber, an on-chip sensing unit, a piezoelectric vibration device, an ultrasonic driver, a trapping optical fiber, a detecting optical fiber, a first fiber laser, a second fiber laser, a feedback cooling module, a quadrant detector, and a cooling optical fiber;

[0009] The on-chip sensing unit and the piezoelectric vibration device are arranged in the vacuum chamber. The on-chip sensing unit is mounted on the piezoelectric vibration device, and the piezoelectric vibration device is electrically connected to the ultrasonic driver. The first fiber laser is connected to the on-chip sensing unit through the trapping optical fiber, the quadrant detector is connected to the on-chip sensing unit through the detecting optical fiber, and the feedback cooling module is connected to the on-chip sensing unit and the second fiber laser through the corresponding cooling optical fiber, and the feedback cooling module is electrically connected to the quadrant detector.

[0010] A microcavity is provided in the on-chip sensing unit. A metasurface is installed in the microcavity. The metasurface is composed of a first metasurface and a second metasurface. The first metasurface and the second metasurface are respectively installed at both ends of the microcavity. The focal points of the first metasurface and the second metasurface coincide. A microsphere is placed in the microcavity between the first metasurface and the second metasurface. Corresponding end channels are respectively opened at both ends of the on-chip sensing unit. The trapping optical fiber is composed of a first trapping optical fiber and a second trapping optical fiber. The first trapping optical fiber passes through the first end channel and is closely attached and aligned with the first metasurface. The second trapping optical fiber passes through the second end channel and is closely attached and aligned with the second metasurface. The laser emitted from the first fiber laser forms a two-beam optical trap in the microcavity after passing through the trapping optical fiber and the metasurface.

[0011] Corresponding side channels are respectively opened on two sides of the on-chip sensing unit. The cooling optical fiber is composed of a first cooling optical fiber, a second cooling optical fiber, and a third cooling optical fiber. The first cooling optical fiber passes through the first end and is closely attached and aligned with the first metasurface. The second cooling optical fiber and the third cooling optical fiber are respectively arranged in the microcavity after passing through the corresponding side channels. The detecting optical fiber is arranged in the microcavity after passing through one of the side channels.

[0012] Both the cooling optical fiber and the detecting optical fiber are aligned with the focal point of the two-beam optical trap.

[0013] The second fiber laser generates a cooling beam. The cooling beam is divided into three paths and then respectively modulated by the feedback cooling module, and then respectively enters the microcavity of the on-chip sensing unit through the corresponding cooling optical fiber.

[0014] The above-mentioned chip-based sensing unit and the piezoelectric vibration device are tightly connected by gluing, pressing or clamping.

[0015] The feedback cooling module described above includes proportional derivative feedback, a band-pass filter and an acousto-optic modulator.

[0016] The number of microspheres is 5 to 6, the shape is spherical, rod-shaped or dumbbell-shaped, the size is on the order of ten micrometers, and the material includes silica.

[0017] II. Control method applied to the device of the above-mentioned on-chip optical trap based on a metalens

[0018] Step 1): Place the chip-based sensing unit and the piezoelectric vibration device into the vacuum chamber. After evacuating the air, turn on the first fiber laser. The laser emitted from the first fiber laser forms a dual-beam optical trap through the trapping fiber and the metalens, and align the cooling fiber and the detection fiber with the focus of the dual-beam optical trap.

[0019] Step 2): Start the ultrasonic driver. The piezoelectric vibration device drives the entire chip-based sensing unit to vibrate, realizing the desorption of the microspheres in the microcavity of the chip-based sensing unit. The microspheres enter the free space and are trapped when passing through the dual-beam optical trap, realizing the starting and supporting in the cavity.

[0020] Step 3): The scattered light beam generated by the optical radiation of the microspheres in the dual-beam optical trap is collected by the detection fiber on the side and then converges on the quadrant detector. Calculate the influence of the microsphere displacement on the scattered light beam collected by the detection fiber, and solve the microsphere displacement information in combination with the parameters of the quadrant detector.

[0021] Step 4): After receiving the microsphere displacement information from the quadrant detector, the feedback cooling module generates a corresponding modulation signal, turns on the second fiber laser, and the cooling light beam emitted by it is divided into three paths. The power is modulated when passing through the feedback cooling module, and then enters the chip-based sensing unit to cool the microspheres and suppress the centroid motion of the microspheres.

[0022] Step 5): Repeat Step 2) - Step 4) to realize the repeated starting, trapping and cooling of the microspheres; during the experiment, if the microspheres at the focus of the dual-beam optical trap are lost, repeat Step 2) to realize the repeated starting of the microspheres, so that the experiment can continue.

[0023] The beneficial effects of the present invention are:

[0024] The present invention introduces a metalens into an optical fiber optical trap. The metalens is ultra-thin, has an extremely small volume, and its working distance is only on the order of a hundred micrometers, making it easy to integrate into the optical fiber optical trap. At the same time, its ability to control the optical field can further improve the stiffness and stability of the optical fiber optical trap. Moreover, the current processing technology of metalenses has been gradually developed and matured, which is conducive to subsequent repeated and large-scale production. Compared with ordinary spatial optical path optical traps, optical fiber optical traps have a small volume and are easy to integrate. Compared with ordinary optical fiber optical traps (such as the self-focusing optical fiber optical trap of CN 110595151 B), the present invention has a larger numerical aperture (NA) of the metalens (a high focusing effect with NA>0.5 can be achieved through phase design), and the scattering efficiency of the microsphere to the captured light focused by the metalens is higher, which will greatly improve the detection sensitivity.

[0025] The present invention also designs a microcavity structure in the on-chip sensing unit to store microspheres, which can realize the repeated pick-up and pick-up in the cavity of the microspheres, avoiding the need to load microspheres multiple times.

[0026] Finally, the present invention introduces multiple optical fibers to realize the displacement detection and cooling of microspheres. The detection optical fiber is a multimode optical fiber with a large aperture and a high numerical aperture, which can realize the sensing and measurement function, and has a smaller volume and higher flexibility compared with using an ordinary objective lens. At the same time, compared with ordinary optical fiber optical traps, three cooling optical fibers are introduced to help stabilize the large-mass microspheres captured in vacuum. The length, width, and height of the entire on-chip sensing unit are all on the order of millimeters, with an extremely small volume, and have an integrated function of capture, detection, and cooling.

[0027] Therefore, the present invention has the characteristics of high integration, high stability, and practicality, and can solve the problems of miniaturization and on-chip integration for the practical application of high-precision vacuum optical trap accelerometers. Description of the Drawings

[0028] Figure 1 is a schematic diagram of the overall structure of this device;

[0029] Figure 2 is a schematic diagram of the structure of the on-chip sensing unit in step 1) of Embodiment 1 (cross-sectional view);

[0030] Figure 3 is a schematic diagram of the structure of the on-chip sensing unit in step 4) of Embodiment 1 (semi-cross-sectional view);

[0031] In the figure: 1. Vacuum chamber; 2. On-chip sensing unit; 3. Piezoelectric vibration device; 4. Capture optical fiber, 4.1 First capture optical fiber, 4.2 Second capture optical fiber; 5. Cooling optical fiber, 5.1 First cooling optical fiber, 5.2 Second cooling optical fiber, 5.3 Third cooling optical fiber; 6. Detection optical fiber; 7. First fiber laser; 8. Feedback cooling module; 9. Quadrant detector; 10. Ultrasonic driver; 11. Second fiber laser; 12. Metalens, 12.1 First metalens, 12.2 Second metalens; 13. Microsphere; 14. Dual-beam optical trap; 15. Scattered light beam; 16. Cooling light beam.

[0032] Figures 1-3 The dimensions of each component in the figure do not represent the actual dimensions of the component. Specific embodiments

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] As Figure 1 、 Figure 2 and Figure 3 shown, the device includes a vacuum chamber 1, an on-chip sensing unit 2, a piezoelectric vibration device 3, an ultrasonic driver 10, a capture optical fiber 4, a detection optical fiber 6, a first fiber laser 7, a second fiber laser 11, a feedback cooling module 8, a quadrant detector 9, and a cooling optical fiber 5;

[0035] The on-chip sensing unit 2 and the piezoelectric vibration device 3 are arranged in the vacuum chamber 1. The on-chip sensing unit 2 is installed on the piezoelectric vibration device 3, and the on-chip sensing unit 2 and the piezoelectric vibration device 3 are tightly connected by means of gluing, pressing or clamping. The piezoelectric vibration device 3 is electrically connected to the ultrasonic driver 10 through a wire; the first fiber laser 7 is connected to the on-chip sensing unit 2 through the capture optical fiber 4, the quadrant detector 9 is connected to the on-chip sensing unit 2 through the detection optical fiber 6, the feedback cooling module 8 is connected to the on-chip sensing unit 2 and the second fiber laser 11 through the corresponding cooling optical fiber 5, and the feedback cooling module 8 is electrically connected to the quadrant detector 9 through a wire. The first fiber laser 7 is used to generate 1064 nm laser, and the second fiber laser 11 is used to generate 532 nm laser.

[0036] The on-chip sensing unit 2 has a cuboid appearance, and its length, width, and height are all in the millimeter range. A microcavity is provided inside the on-chip sensing unit 2, and a metalens 12 is installed in the microcavity. The substrate of the metalens 12 is silica, and nanosilicon pillars are distributed on it. By designing and manufacturing the geometric structure (nanosilicon pillars), the control of the optical wave characteristics (including phase, amplitude, and polarization) can be achieved, and the profile, position, and angle of the sub-wavelength structure can be adjusted, thereby controlling the focusing and imaging characteristics of the metalens 12. The radial dimension and focal length of the metalens 12 are in the hundreds of micrometers range, and the thickness is in the millimeter range. After phase design, its NA can exceed 0.5, and it can highly focus the light beam. The metalens 12 is composed of a first metalens 12.1 and a second metalens 12.2. The first metalens 12.1 and the second metalens 12.2 are respectively installed at both ends of the microcavity, and are arranged at intervals along the optical axis between the first metalens 12.1 and the second metalens 12.2. The foci of the first metalens 12.1 and the second metalens 12.2 coincide. A microsphere 13 is placed in the microcavity between the first metalens 12.1 and the second metalens 12.2. Corresponding end channels are respectively opened at both ends of the on-chip sensing unit 2. The radial dimension of the trapping optical fiber 4 is in the tens of micrometers range and is used to transmit 1064 nm laser light. The trapping optical fiber 4.1 is composed of a first trapping optical fiber 4.1 and a second trapping optical fiber 4.2. The first trapping optical fiber 4.1 passes through the first end channel and is in close contact with and aligned with the first metalens 12.1. The second trapping optical fiber 4.2 passes through the second end channel and is in close contact with and aligned with the second metalens 12.2. The first trapping optical fiber 4.1 and the second trapping optical fiber 4.2 are inserted axially into the on-chip sensing unit 2. The laser light emitted from the first fiber laser 7 forms a double-beam optical trap 14 in the microcavity after passing through the trapping optical fiber 4 and the metalens 12. It is the microsphere 13 that scatters the trapping light beam emitted from the trapping optical fiber 4 to form a scattered light beam 15. The scattered light beam 15 is collected by the detection optical fiber 6 and then converges on the quadrant detector 9.

[0037] Corresponding side channels are respectively opened on two of the sides of the on-chip sensing unit 2. The cooling optical fiber 5 is composed of a first cooling optical fiber 5.1, a second cooling optical fiber 5.2, and a third cooling optical fiber 5.3. The diameters of the end channels and the side channels are both in the tens of micrometers range. The first cooling optical fiber 5.1 passes through the first end and is in close contact with and aligned with the first metalens 12.1, that is, sharing the same optical path with the first trapping optical fiber 4.1. The second cooling optical fiber 5.2 and the third cooling optical fiber 5.3 are respectively arranged in the microcavity after passing through the corresponding side channels; the detection optical fiber 6 is arranged in the microcavity after passing through one of the side channels. The detection optical fiber 6 is inserted radially into the on-chip sensing unit 2; that is, the detection optical fiber 6 shares the same optical path with the second cooling optical fiber 5.2. The detection optical fiber 6 is a multimode optical fiber with a large aperture and a high numerical aperture NA, Numerical Aperture, and is used to collect the scattered light beam 15 in the microcavity. The cooling optical fiber 5 and the detection optical fiber 6 are both aligned with the focus of the double-beam optical trap 14.

[0038] The second fiber laser 11 generates a cooling beam. After being divided into three paths, the cooling beam is modulated by the feedback cooling module 8 respectively, and then enters the microcavity of the on-chip sensing unit 2 through the corresponding cooling optical fibers respectively.

[0039] The piezoelectric vibration device 3 utilizes the inverse piezoelectric effect of lead zirconate titanate piezoelectric ceramics PZT, that is, a high-speed alternating electric field is applied to the PZT by the ultrasonic driver 10, so that it rapidly expands and contracts in the thickness direction. It forms a support component together with the ultrasonic driver 10.

[0040] In specific implementation, the feedback cooling module 8 includes proportional derivative feedback, a band-pass filter and an acousto-optic modulator AOM.

[0041] The number of microspheres 13 is 5 to 6, the shape is spherical, rod-shaped or dumbbell-shaped, the size is on the order of ten micrometers, and the material includes silica, which is stored in the microcavity of the on-chip sensing unit 2.

[0042] The specific application embodiments of the present invention and their implementation processes are as follows:

[0043] Step 1): Preparation work: Place the on-chip sensing unit 2 and the piezoelectric vibration device 3 into the vacuum chamber 1. After evacuating the air, turn on the 1064nm fiber laser 7. The 1064nm laser is equally divided into two paths and transmitted through the first capture optical fiber 4.1 and the second capture optical fiber 4.2. After passing through the first superlens 12.1 and the second superlens 12.2 respectively from both ends of the on-chip sensing unit 2, a counter-propagating double-beam optical trap 14 is formed. Align the cooling optical fiber 5 and the detection optical fiber 6 with the focus of the double-beam optical trap 14.

[0044] Step 2): Support the microsphere: Start the ultrasonic driver 10. The piezoelectric vibration device 3 drives the entire on-chip sensing unit 2 to vibrate, realizing the desorption of the microsphere 13 in the microcavity of the on-chip sensing unit 2 and entering the free space. When passing through the double-beam optical trap 14, it is captured to realize on-chip support;

[0045] Step 3): As Figure 3As shown in the figure, the microsphere 13 in the dual-beam optical trap 14 generates a scattered light beam 15 under light radiation. After being collected by the detection optical fiber 6 on the side, it hits the quadrant detector 9. In the detection simulation and design, the following calculation steps are adopted: (1) Calculate the light field distribution near the detection optical fiber 6 without the small ball; (2) For the small ball at any position near the focus, use the Mie theory or Rayleigh scattering theory to solve the scattered light field distribution of the plane wave emitted from each local part in the dual-beam optical trap 14; (3) In the lateral scattering, find the interference light field of the total scattered wave and the unscattered wave at the end face of the detection optical fiber 6, so as to calculate the total scattered field in the corresponding solid angle and the received light intensity of the detection optical fiber 6; (4) According to the light field distribution near the detection optical fiber 6 without the small ball, the scattered light field distribution of the plane wave when the small ball is near the focus, the total scattered field in the solid angle corresponding to the detection optical fiber 6, the received light intensity of the detection optical fiber 6, and the volt-meter conversion coefficient (i.e., the responsivity) of the quadrant detector 9, find the displacement information of the corresponding microsphere 13. The lateral multimode detection optical fiber will collect the trapped light and cooling light scattered from the microsphere. Since the wavelengths of the trapped light and the cooling light are different, the dichroic mirror can be used to process the scattered light beam 15 collected by the detection optical fiber 6 without affecting the detection of the microsphere displacement.

[0046] Step 4): As Figure 3 shown in the figure, the 532 nm cooling light beam 16 is emitted from the 532 nm fiber laser and divided into three paths. After passing through the feedback cooling module 8, its power is modulated, and then it enters the on-chip sensing unit 2 as the cooling light beam 16 to cool the microsphere 13 and suppress the centroid movement of the microsphere 13. Among them, the feedback cooling module 8 receives the microsphere displacement information from the quadrant detector 9 in step 3), and generates a corresponding modulation signal after passing through units such as proportional derivative feedback, band-pass filter, and AOM (acousto-optic modulator).

[0047] Step 5): Repeat steps 2)-4) to realize the repeated pick-up, capture, and cooling of the microsphere 13; during the experiment, if the microsphere 13 at the focus of the dual-beam optical trap 14 is lost, repeat step 2) to realize the repeated pick-up of the microsphere 13, so as to continue the experiment.

[0048] In summary, the present invention introduces a metalens into the fiber optical trap, greatly reducing the volume of the on-chip optical trap while improving the detection sensitivity; designs a microcavity structure to store the microsphere to realize the repeated pick-up and capture of the microsphere; at the same time, introduces multiple optical fibers to realize the microsphere displacement detection and cooling, making the on-chip sensing unit have the characteristics of high integration, high stability, and practicability.

[0049] The above specific embodiments are used to explain the present invention rather than limit the present invention. Any modification and change made within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. An apparatus for a high-vacuum on-chip optical trap based on a metalens, characterized in that, It includes a vacuum chamber (1), an on-chip sensing unit (2), a piezoelectric vibration device (3), an ultrasonic driver (10), a capture optical fiber (4), a detection optical fiber (6), a first fiber laser (7), a second fiber laser (11), a feedback cooling module (8), a quadrant detector (9), and a cooling optical fiber (5); The on-chip sensing unit (2) and the piezoelectric vibration device (3) are arranged inside the vacuum chamber (1). The on-chip sensing unit (2) is installed on the piezoelectric vibration device (3), and the piezoelectric vibration device (3) is electrically connected to the ultrasonic driver (10). The first fiber laser (7) is connected to the on-chip sensing unit (2) through the capture optical fiber (4), the quadrant detector (9) is connected to the on-chip sensing unit (2) through the detection optical fiber (6), the feedback cooling module (8) is connected to the on-chip sensing unit (2) and the second fiber laser (11) through the corresponding cooling optical fiber (5), and the feedback cooling module (8) is electrically connected to the quadrant detector (9); A microcavity is arranged inside the on-chip sensing unit (2). A metalens (12) is installed in the microcavity. The metalens (12) is composed of a first metalens (12.1) and a second metalens (12.2). The first metalens (12.1) and the second metalens (12.2) are respectively installed at both ends of the microcavity. The focal points of the first metalens (12.1) and the second metalens (12.2) coincide. A microsphere (13) is placed in the microcavity between the first metalens (12.1) and the second metalens (12.2). Corresponding end channels are respectively opened at both ends of the on-chip sensing unit (2). The capture optical fiber (4) is composed of a first capture optical fiber (4.1) and a second capture optical fiber (4.2). The first capture optical fiber (4.1) passes through the first end channel and is closely attached to and aligned with the first metalens (12.1). The second capture optical fiber (4.2) passes through the second end channel and is closely attached to and aligned with the second metalens (12.2). The laser emitted from the first fiber laser (7) forms a dual-beam optical trap (14) in the microcavity after passing through the capture optical fiber (4) and the metalens (12).

2. The device of a high-vacuum on-chip optical trap based on a metalens according to claim 1, wherein Corresponding side channels are respectively opened on two sides of the on-chip sensing unit (2). The cooling optical fiber (5) is composed of a first cooling optical fiber (5.1), a second cooling optical fiber (5.2), and a third cooling optical fiber (5.3). The first cooling optical fiber (5.1) passes through the first end and is closely attached to and aligned with the first metalens (12.1). The second cooling optical fiber (5.2) and the third cooling optical fiber (5.3) are respectively arranged in the microcavity after passing through the corresponding side channels. The detection optical fiber (6) is arranged in the microcavity after passing through one of the side channels.

3. The device of a high-vacuum on-chip optical trap based on a metalens according to claim 1, wherein Both the cooling optical fiber (5) and the detection optical fiber (6) are aligned with the focal point of the dual-beam optical trap (14).

4. The device of a high-vacuum on-chip optical trap based on a metasurface according to claim 1, wherein The second fiber laser (11) generates a cooling beam (16). The cooling beam (16) is divided into three paths and then respectively modulated by the feedback cooling module (8), and is respectively transmitted into the microcavity of the on-chip sensing unit (2) through the corresponding cooling optical fiber (5).

5. The device of a high-vacuum on-chip optical trap based on a metalens according to claim 1, wherein The described chip-based sensing unit (2) and the piezoelectric vibration device (3) are tightly connected by gluing, pressing, or clamping.

6. The device of a high-vacuum on-chip optical trap based on a metalens according to claim 1, characterized in that, The described feedback cooling module (8) includes proportional derivative feedback, a band-pass filter, and an acou-optic modulator.

7. The device of a high-vacuum on-chip optical trap based on a metasurface according to claim 1, characterized in that, The number of the described microspheres (13) is 5 to 6, the shapes are spherical, rod-shaped, or dumbbell-shaped, the size is on the order of ten micrometers, and the materials include silica.

8. A control method for a device applying the on-chip optical trap in high vacuum based on a metalens according to any one of claims 1-7, characterized in that, It includes the following steps: Step 1): Place the chip-based sensing unit (2) and the piezoelectric vibration device (3) into the vacuum chamber (1). After evacuating the air, turn on the first fiber laser (7). The laser emitted from the first fiber laser (7) passes through the trapping fiber (4) and the metalens (12) to form a dual-beam optical trap (14), and align the cooling fiber (5) and the detection fiber (6) with the focus of the dual-beam optical trap (14). Step 2): Start the ultrasonic driver (10). The piezoelectric vibration device (3) will drive the entire chip-based sensing unit (2) to vibrate, realizing the desorption of the microspheres (13) in the microcavity of the chip-based sensing unit (2). The microspheres (13) enter the free space and are trapped when passing through the dual-beam optical trap (14), realizing the in-cavity lasing start. Step 3): The scattered light beam (15) generated by the optical radiation of the microspheres (13) in the dual-beam optical trap (14) is collected by the detection fiber (6) on the side and then converges on the quadrant detector (9). Calculate the influence of the displacement of the microspheres (13) on the scattered light beam (15) collected by the detection fiber (6), and solve the microsphere displacement information in combination with the parameters of the quadrant detector (9). Step 4): After receiving the microsphere displacement information from the quadrant detector (9), the feedback cooling module (8) generates a corresponding modulation signal, and turn on the second fiber laser (11). The cooling light beam (16) emitted by it is divided into three paths. When passing through the feedback cooling module (8), the power is modulated, and then enters the chip-based sensing unit (2) to cool the microspheres (13), suppressing the centroid movement of the microspheres (13). Step 5): Repeat Step 2) - Step 4) to realize the repeated lasing start, trapping, and cooling of the microspheres (13); during the experiment, if the microspheres (13) at the focus of the dual-beam optical trap (14) are lost, repeat Step 2) to realize the repeated lasing start of the microspheres (13), so that the experiment can continue.

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