Wavelength division multiplexing trapping device for single-beam vacuum optical trap and method for measuring extremely weak forces

Abstract

This invention discloses a wavelength division multiplexing (WDM) trapping device and a method for measuring extremely weak forces in a single-beam vacuum optical trap. A fiber laser emits a laser beam, which passes sequentially along the fiber through a fiber acousto-optic modulator, a fiber beam splitter, and a 1064nm fiber collimator to obtain beam A. Beam A is transmitted through a dichroic mirror into a vacuum cavity, trapping and detecting micro / nano particles. Beams B, C, and D, obtained through multiple fiber beam splitters, a PPLN waveguide frequency doubling module, a fiber electro-optic modulator, and a 532nm fiber collimator, sequentially enter the vacuum cavity to triaxially cool the micro / nano particles in a vacuum environment. At this point, the micro / nano particles are in a stable state. A voltage is applied to the electrode plate, reducing the intensity of beam A, ultimately achieving a balance between electric field force and gravity. The electric field force is then used as the measurement value for the gravity of the micro / nano particles. This invention employs a wavelength division multiplexing method, achieving triaxial cooling, trapping, and detection with only one light source, and using optical fiber to replace most optical components, resulting in greater integration.

Description

Technical Field

[0001] This invention relates to the field of precision measurement, and more particularly to a wavelength division multiplexing capture device for a single-beam vacuum optical trap and a method for measuring extremely weak forces. Background Technology

[0002] The measurement of extremely weak forces has facilitated applications in fields such as magnetic resonance force microscopy, matter-wave interferometry, close-range gravitational physics testing, and inertial sensing. Furthermore, my country's latest "Metrology Development Plan (2021-2035)" proposes technological requirements for the measurement of piconewton-level microforces and the quantum transformation of mass units. The favorable environmental decoupling of optical levitation mechanical systems in high vacuum allows for the measurement of extremely weak forces at room temperature. In vacuum optical tweezers, the momentum exchange between light and micro / nano particles allows for the stable confinement and manipulation of these particles within optical traps. The forces acting on micro / nano particles within the optical trap can be categorized into scattering forces and gradient forces. The scattering force travels along the direction of light propagation, while the gradient force points towards the direction of decreasing light potential energy. Neglecting gravity, when the resultant force of the scattering and gradient forces on a particle at a certain position is zero, it will be trapped at this equilibrium position, i.e., the center of the optical trap. The fundamental principle of extremely weak force measurement is based on the wave-dissipation theorem, primarily constrained by Brownian motion. The power spectral density (PSD) is expressed as S... F =4k B T0mΩ0 / Q, where k B Let T0 be Boltzmann's constant, m be the mass of the micro / nano particle, Ω0 be the oscillation frequency, and Q be the quality factor. Then, the measurable weakest force at temperature T0 is: Where Γ0 is the damping ratio and b is the measurement bandwidth. Based on the measurement of the weakest force, a vertically upward optical trap weakest force measurement device is used. When the micro-nano particles in the optical trap are in equilibrium, they are subject to gravity and light scattering force. By applying an electric field force near the micro-nano particles, the light scattering force is weakened, and finally the micro-nano particles are in equilibrium through the electric field force. At this time, we have G = F, where G is the measured gravity value, F is the known applied electric field force, i.e., mg = F, where m is the mass of the ball and g is the gravitational acceleration. Then we can obtain m = F / g.

[0003] Existing vacuum optical tweezers technology generally employs a spatial optical path system for measuring extremely weak forces. This system uses 1064nm wavelength light to capture micro- and nano-particles through a converging lens, and measures extremely weak forces by means of thermal noise limits, electrostatic force detection, application of alternating electric fields, and electric field forces.

[0004] The article "Three-dimensional force-field microscopy with optically levitated microspheres" discloses a system for measuring extremely weak forces based on vacuum optical tweezers. It mainly includes 1064nm wavelength light as the trapping light for micro / nano particles and 532nm wavelength light as the detection signal light. Numerous spatial optical components, such as lenses, mirrors, polarizing beam splitters, galvanometers, isolators, and four-quadrant detectors, are required to construct the system's optical path, thereby enabling the measurement of extremely weak forces. However, the following problems need to be addressed:

[0005] (1) The use of a large number of spatial optical components to build the optical path system limits the application requirements for system integration and miniaturization. The system requirements in the article use a large number of spatial optical components to build the optical path system. The spatial optical components all have requirements on focal length, which makes the system device require a large space and inconvenient to move. This greatly affects the application of the extremely weak force measurement system that needs to be integrated and miniaturized.

[0006] (2) The use of 532nm as the probe light in the system device limits the application requirements for system integration and miniaturization. The requirement in the article to use 532nm as the probe light source requires a 532nm laser and a large number of spatial optical components, which makes the system device require a large space and inconvenient to move. This greatly affects the application of the need for integration and miniaturization of the extremely weak force measurement system and increases the additional cost of the system.

[0007] In summary, existing technologies, in order to achieve highly sensitive and accurate measurement of extremely weak forces in practical applications, suffer from problems such as large size, complex optical paths, inconvenient mobility, and susceptibility to changes in complex external environments. This makes it difficult for vacuum optical tweezers-based extremely weak force measurement devices to leave the laboratory, hindering their miniaturization, integration, engineering, and application. To overcome this deficiency, existing technologies have attempted to mask this technical limitation by continuously simplifying the spatial optical path system. However, this limitation continues to restrict the miniaturization and application of vacuum optical tweezers-based extremely weak force measurement devices, and remains to be addressed. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention proposes a wavelength division multiplexing trapping device for a single-beam vacuum optical trap and a method for measuring extremely weak forces.

[0009] The specific technical solution is as follows:

[0010] A wavelength division multiplexing trapping device for a single-beam vacuum optical trap includes: a fiber laser, a fiber beam splitter, a fiber acousto-optic modulator, a 1064nm fiber collimator, a dichroic mirror, a vacuum cavity, a PPLN waveguide frequency doubling module, a fiber electro-optic modulator, a 532nm fiber collimator, a four-quadrant detector, and a control terminal.

[0011] The fiber laser emits 1064nm light. The fiber laser, fiber acousto-optic modulator, and first fiber beam splitter are sequentially connected via optical fibers. One output of the first fiber beam splitter is connected to a 1064nm fiber collimator via an optical fiber, outputting beam A; the other output is connected to a second fiber beam splitter via an optical fiber. One output of the second fiber beam splitter outputs a reference beam and is connected to a four-quadrant detector via an optical fiber; the other output is sequentially connected to a PPLN waveguide frequency doubling module and a third fiber beam splitter via optical fibers. The N-waveguide frequency doubling module is used to double the frequency of 1064nm wavelength light to 532nm; one output of the third fiber beam splitter is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam B; the other output is connected to the fourth fiber beam splitter via an optical fiber; one output of the fourth fiber beam splitter is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam C; the other output is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam D;

[0012] The light beam A enters the vacuum cavity after being transmitted through a dichroic mirror. The vacuum cavity contains a lens, a vacuum mirror, electrode plates, and micro / nano particles. After being focused by the lens, light beam A is redirected by 90° under the action of the vacuum mirror. The electrode plates are positioned along the optical path of light beam A after its redirection, and the micro / nano particles are located between the two electrode plates and can be captured by light beam A. After passing through the micro / nano particles, light beam A continues to propagate in its original direction, now carrying the state information of the micro / nano particles. It is then redirected again by 90° by another vacuum mirror, and after being completely collected by the lens, it leaves the vacuum cavity carrying the complete state information of the micro / nano particles. The beams are coupled to a four-quadrant detector outside the vacuum cavity, which acquires signals and transmits them to the control terminal. The optical axis of beam A entering the vacuum cavity is defined as the Z-axis. According to the right-hand rule, the two directions perpendicular to the Z-axis are defined as the X-axis and Y-axis, respectively. Beams B and C enter the vacuum cavity along the Y-axis or X-axis, respectively, to cool the micro-nano particles, and beams B and C enter the vacuum cavity in different directions. Beam D, after being reflected by a dichroic mirror, enters the vacuum cavity along the Z-axis together with beam A to cool the micro-nano particles.

[0013] Furthermore, the optical power of the fiber laser is 0-5W, and the modulation optical power of the fiber acousto-optic modulator is 1-5W.

[0014] Furthermore, the lens has a focal length of 75-300mm, the distance between the two electrode plates is 20-50mm, and the diameter of the micro-nano particles is 2-30μm.

[0015] Furthermore, the optical fiber electro-optic modulator has a modulation optical power of 1W.

[0016] Furthermore, beams A, B, C, and D enter the vacuum cavity through the vacuum cavity mirror on the vacuum cavity.

[0017] Furthermore, the dichroic mirror exhibits near-complete transmission at a wavelength of 1064 nm and near-complete reflection at a wavelength of 532 nm.

[0018] A wavelength division multiplexing (WDM) method for extremely weak force metrology using a single-beam vacuum optical trap, implemented based on the aforementioned WDM trap capture device, is detailed below:

[0019] The fiber laser emits a 1064nm wavelength laser beam, which travels sequentially along the fiber through a fiber acousto-optic modulator and the first fiber beam splitter. One of the split beams travels along the fiber through a 1064nm fiber collimator to become a spatial light beam A. After being transmitted through a dichroic mirror, it enters the vacuum cavity horizontally. After passing through a lens to form a focused beam, beam A changes from a horizontal to a vertical state after passing through a vacuum mirror. It then passes through an electrode plate and acts on the micro-nano particles for capture. Simultaneously, beams B, C, and D enter the vacuum cavity in the X, Y, and Z directions, respectively, to perform triaxial cooling on the micro-nano particles.

[0020] When micro-nano particles are captured, the vacuum chamber begins to operate, evacuating the cavity. When the vacuum level reaches a threshold, a four-phase detector collects signals and transmits them to the control terminal for data analysis. The micro-nano particle signal results are then fed back by a cooling mechanism, which modulates the light intensities of beams B, C, and D using an optical fiber electro-optic modulator, bringing the micro-nano particles into a stable capture state. At this point, a voltage is applied to the electrode plate, creating an electric field. As the electric field increases, the light intensity of beam A decreases until a balance between the electric field and gravity is achieved, capturing the micro-nano particles. The electric field at this equilibrium state is used as the measured value of the gravity of the micro-nano particles.

[0021] After passing the micro-nano particles, the beam continues to propagate vertically, carrying the state of the micro-nano particles. After passing the reflector, the beam changes from vertical to horizontal again. After passing through the lens to collect complete information on the state of the micro-nano particles, it leaves the vacuum cavity and is coupled to the four-quadrant detector for signal acquisition and transmission to the control terminal. The control terminal obtains the signal containing the state of the micro-nano particles, thereby achieving precise measurement of extremely weak forces.

[0022] Furthermore, the micro-nano particles fall from above beam A via piezoelectric ceramic support and are captured in the optical trap trapping region where the focus of beam A is located.

[0023] Furthermore, the threshold value of the vacuum level within the vacuum chamber is 1x10⁻¹⁰. -6 mbar.

[0024] Furthermore, when micro- and nano-particles are in equilibrium under light-cooled high-vacuum conditions, the mass of the micro- and nano-particles... Where q is the charge, E is the electric field strength, and g is the gravitational acceleration.

[0025] The beneficial effects of this invention are:

[0026] (1) The present invention uses wavelength division multiplexing method, uses 1064nm light source wavelength division multiplexing frequency doubling to 532nm to achieve triaxial cooling, and uses 1064nm light as capture light and probe light, so that triaxial cooling, capture and probe functions can be achieved using only one light source.

[0027] (2) This invention proposes a wavelength division multiplexing capture device for a single-beam vacuum optical trap, which uses fiber optic components to replace a large number of space optical components. It is smaller, more integrated and miniaturized than the existing system, and is more convenient in terms of mobility and application. It has a superior advantage in the application of extremely weak force measurement in the field of precision measurement. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the optical path of the wavelength division multiplexing capture device of the single-beam vacuum optical trap of the present invention.

[0029] Figure 2 This is a schematic diagram illustrating the principle of the present invention for measuring extremely weak forces.

[0030] In the figure, the components are: 1. Fiber laser; 2. Fiber beam splitter; 3. Fiber acousto-optic modulator; 4. 1064nm fiber collimator; 5. Dichroic mirror; 6. Vacuum cavity; 7. Lens; 8. Vacuum mirror; 9. Electrode plate; 10. Micro / nano particles; 11. PPLN waveguide frequency doubling module; 12. Fiber electro-optic modulator; 13. Vacuum cavity mirror; 14. 532nm fiber collimator; 15. Four-quadrant detector; and 16. Control terminal. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In the following description, reference is made to "one specific embodiment," which describes a subset of all possible embodiments; however, it is understood that "one specific embodiment" describes the same or different subsets of all possible embodiments and may be combined with each other without conflict.

[0033] Unless otherwise defined, all techniques used herein have the same scientific or technical meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0034] like Figure 1 As shown, a wavelength division multiplexing (WDM) trapping device for a single-beam vacuum optical trap includes: a fiber laser 1, four fiber beam splitters 2, a fiber acousto-optic modulator 3, a 1064nm fiber collimator 4, a dichroic mirror 5, a vacuum cavity 6, a PPLN waveguide frequency doubling module 11, three fiber electro-optic modulators 12, three 532nm fiber collimators 14, a four-quadrant detector 15, and a control terminal 16.

[0035] Fiber laser 1 is sequentially connected to fiber acousto-optic modulator 3 and first fiber beam splitter 2 via optical fibers. Fiber laser 1 emits a laser beam with a wavelength of 1064nm and an optical power of 0-5W. Fiber acousto-optic modulator 3 modulates the optical power of the light beam with a power of 1-5W. Fiber beam splitter 2 splits a single beam into two. Fiber laser 1 emits a 1064nm laser beam along the optical fiber, which passes sequentially through fiber acousto-optic modulator 3 and first fiber beam splitter 2. After passing through first fiber beam splitter 2, the beam is split into two. One output end of first fiber beam splitter 2 is connected to 1064nm fiber collimator 4 via an optical fiber, and the beam is converted into spatial light beam A after passing through 1064nm fiber collimator 4. The other output end is connected to the input end of second fiber beam splitter 2 via an optical fiber. One output of the second fiber beam splitter 2 is connected to the four-quadrant detector 15 via an optical fiber, and the beam output from this output is denoted as the reference beam E. The other output is connected to the input of the PPLN waveguide frequency doubling module 11 via an optical fiber. The PPLN waveguide frequency doubling module 11 is used to double the 1064nm wavelength light to 532nm. The output of the PPLN waveguide frequency doubling module 11 is connected to the input of the third fiber beam splitter 2 via an optical fiber. One output of the third fiber beam splitter 2 is sequentially connected to the first fiber electro-optic modulator 12 and the first 532nm fiber collimator 14 via an optical fiber. After passing through the first 532nm fiber collimator 14, the beam is converted into a spatial light beam B. The other output is connected to the input of the fourth fiber beam splitter 2 via an optical fiber. One output of the fourth fiber beam splitter 2 is sequentially connected to the second fiber electro-optic modulator 12 and the second 532nm fiber collimator 14. After passing through the second 532nm fiber collimator 14, the beam is converted into a spatial light beam C. The other output is sequentially connected to the third fiber electro-optic modulator 12 and the third 532nm fiber collimator 14. After passing through the third 532nm fiber collimator 14, the beam is converted into a spatial light beam D. The modulation power of the three fiber electro-optic modulators 12 is 1W.

[0036] The spatial light beam A is transmitted through the dichroic mirror 5 and enters the vacuum cavity 6 horizontally through the vacuum cavity mirror 13 on the vacuum cavity 6. The dichroic mirror 5 has high transmission at a wavelength of 1064nm and high reflection at a wavelength of 532nm.

[0037] The vacuum cavity 6 contains two lenses 7, two vacuum mirrors 8, two electrode plates 9, and micro / nano particles 10. Lenses 7 are arranged coaxially along the optical path of beam A entering the vacuum cavity 6, with a focal length of 75-300 mm. One vacuum mirror 8 is positioned along the optical path of lens 7 at a 45° angle to the horizontal plane, redirecting beam A by 90°, thus converting the horizontal beam into a vertical beam. The two electrode plates 9 are positioned along the optical path after the redirection of beam A, with through-holes at positions corresponding to beam A to allow the beam to pass through. The distance between the two electrode plates 9 ranges from 20-50 mm. Micro / nano particles 10 are arranged between the two electrode plates 9, with a diameter ranging from 2-30 μm. After passing through electrode plate 9, beam A continues to propagate in its original direction. After passing through another vacuum reflector 8, beam A is turned 90°, that is, the vertical beam is turned into a horizontal beam again. Lens 7 is arranged coaxially on the optical path after beam A is turned. After beam A carrying micro-nano particle state information is collected by lens 7, it passes through vacuum cavity mirror 13 and leaves vacuum cavity 6. It is coupled to four-quadrant detector 15 outside vacuum cavity 6 for signal acquisition and transmission to control terminal 16.

[0038] Assuming that the optical axis of beam A when it enters vacuum cavity 6 is the Z-axis, according to the right-hand rule, the two directions perpendicular to the Z-axis are defined as the X-axis and Y-axis, respectively.

[0039] The spatial light beam B enters the vacuum cavity 6 along the X direction (or Y direction) through the vacuum cavity mirror 13 on the vacuum cavity 6 and acts on the micro-nano particles 10.

[0040] The spatial light beam C enters the vacuum cavity 6 along the Y direction (or X direction) through the vacuum cavity mirror 13 on the vacuum cavity 6 and acts on the micro-nano particles 10.

[0041] After being reflected by the dichroic mirror 5, the spatial light beam D enters the vacuum cavity 6 along the Z direction with the beam A and acts on the micro-nano particles 10.

[0042] Based on the wavelength division multiplexing (WDM) trapping device for the single-beam vacuum optical trap described above, a wavelength division multiplexing method for extremely weak force measurement using a single-beam vacuum optical trap is provided, as follows:

[0043] Fiber laser 1 emits a 1064nm wavelength laser beam, which travels sequentially along the fiber through fiber acousto-optic modulator 3 and the first fiber beam splitter 2. One beam travels along the fiber through a 1064nm fiber collimator 4, becoming a spatial beam A. This beam then passes through a dichroic mirror 5, passes through a vacuum cavity mirror 13, and enters the vacuum cavity 6 horizontally. After passing through a lens 7 to form a focused beam, and then through a vacuum reflector 8, the beam changes from horizontal to vertical. It then passes through a small hole on an electrode plate 9 and acts on micro / nano particles 10. The micro / nano particles 10, supported by piezoelectric ceramics, fall from above the beam and are captured in the optical trap region formed by the focal point of beam A. Simultaneously, another beam is split multiple times, passing sequentially through fiber electro-optic modulator 12 and a 532nm fiber collimator 14 to obtain spatial beams B, C, and D, which enter the vacuum cavity 6 along the X, Y, and Z directions respectively and act on the micro / nano particles 10.

[0044] When the micro / nano particles 10 are captured, the vacuum cavity 10 starts working, evacuating the cavity until the vacuum level is greater than or equal to a vacuum threshold. In this embodiment, the vacuum threshold is 1 x 10⁻⁶. -6 mbar. When the vacuum level reaches the threshold, the signals of the reference beam E and the beam A containing the state of the micro / nano particles 10 are collected by the four-quadrant detector 15 and transmitted to the control terminal 16 for data analysis. Based on the signal results of the micro / nano particles 10, the beams B, C, and D are adjusted to provide cooling feedback for the micro / nano particles 10. Specifically, the intensity of beam B is modulated by the fiber electro-optic modulator 12 to cool the micro / nano particles 10 in the Y direction; the intensity of beam C is modulated by the fiber electro-optic modulator 12 to cool the micro / nano particles 10 in the X direction; and the intensity of beam D is modulated by the fiber electro-optic modulator 12 to cool the micro / nano particles 10 in the Z direction. The combined action of beams B, C, and D achieves triaxial cooling of the micro / nano particles 10, keeping them in a stable captured state and reducing the positional error of the micro / nano particles 10.

[0045] Once the micro-nano particle 10 is in a captured and stable state, a voltage is applied to the two electrode plates 9, creating an electric field between them. Through signal feedback from the four-quadrant detector 15, the intensity of the captured light (i.e., beam A) in the Z direction decreases accordingly as the electric field strengthens, eventually reaching a state of equilibrium between the electric field and gravity, thus capturing the micro-nano particle 10. The electric field at this equilibrium state is used as the measured value of the gravity. After passing the micro-nano particle 10, the beam carries its current state and continues to propagate vertically. It passes through the small hole in the electrode plate 9, then through the reflector 8, where it changes from vertical to horizontal. The beam is then focused by the lens 7 and exits the vacuum cavity 6 through the vacuum cavity mirror 13, coupling to the four-quadrant detector 15 outside the vacuum cavity 6 for signal acquisition and transmission to the control terminal 16. The control terminal 16 receives the signal carrying the current state of the micro-nano particle 10, thus achieving precise measurement of extremely weak forces.

[0046] like Figure 2 As shown, in the vacuum cavity 6, the light beam A is focused at the focal point of the lens 7 as the trapping light. The area where the focal point is located serves as the light trapping area. The micro-nano particles 10 are stably trapped in the light trapping area by the trapping light. An electric field is applied above and below the sphere using the electrode plate 9. At the same time, the light power of the light beam A is reduced. By precisely controlling the electric field force to balance the measured gravity, the electric field force and gravity on the micro-nano particles 10 are brought into a state of equilibrium. Thus, the gravity of the micro-nano particles 10 is measured based on the provided electric field force.

[0047] The formula for measuring extremely weak forces based on a suspended optical force system is:

[0048]

[0049] Given F = qE, the measured quantity G = mg, where F is the electric force, q is the charge, E is the electric field strength, G is the measured gravity, m is the mass of the ball, and g is the acceleration due to gravity. driv For the additional force being measured, For the inertial force of micro- and nano-particle motion, F therm For random forces arising from molecular collisions, F drag For molecular resistance, F optz This refers to the light radiation pressure in the vertical direction.

[0050] When the micro / nano particle 10 is in a state of electric field equilibrium, and the only additional force being measured is gravity, F driv =0; at the equilibrium position F optz =0; in a high vacuum environment (i.e., greater than or equal to 1x10⁻⁶), -6 (mbar) and when the micro / nano particles 10 are in a photocooled state F therm F drag The overall noise level is as low as Negligible. Therefore, at equilibrium, F+G=0, thus yielding the mass of micro / nano particles 10. This invention enables precise measurement of extremely weak forces. It can measure extremely weak forces in micro- and nano-particles with diameters of 2-30 μm, offering a wider measurement range compared to existing systems for measuring extremely weak forces.

[0051] In summary, this invention employs wavelength division multiplexing (WDM) to achieve triaxial cooling by frequency doubling of a 1064nm light source to 532nm, and uses 1064nm light as both the capture and probe light. This allows for triaxial cooling, capture, and probe functions using only one light source. Furthermore, the use of fiber optic components to replace a large number of space optical components makes the system more suitable for integration and engineering.

[0052] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The above description is merely a preferred embodiment of the present invention, intended to enable those skilled in the art to understand or implement the invention, and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art, and these modifications to the embodiments will be readily apparent. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A wavelength division multiplexing trapping device for a single-beam vacuum optical trap, characterized in that, include: Fiber laser, fiber beam splitter, fiber acousto-optic modulator, 1064nm fiber collimator, dichroic mirror, vacuum cavity, PPLN waveguide frequency doubling module, fiber electro-optic modulator, 532nm fiber collimator, four-quadrant detector, control terminal. The fiber laser emits 1064nm light. The fiber laser, fiber acousto-optic modulator, and first fiber beam splitter are sequentially connected via optical fibers. One output of the first fiber beam splitter is connected to a 1064nm fiber collimator via an optical fiber, outputting beam A; the other output is connected to a second fiber beam splitter via an optical fiber. One output of the second fiber beam splitter outputs a reference beam and is connected to a four-quadrant detector via an optical fiber; the other output is sequentially connected to a PPLN waveguide frequency doubling module and a third fiber beam splitter via optical fibers. The N-waveguide frequency doubling module is used to double the frequency of 1064nm wavelength light to 532nm; one output of the third fiber beam splitter is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam B; the other output is connected to the fourth fiber beam splitter via an optical fiber; one output of the fourth fiber beam splitter is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam C; the other output is sequentially connected to a fiber electro-optic modulator and a 532nm fiber collimator via an optical fiber, outputting beam D; The light beam A enters the vacuum cavity after being transmitted through a dichroic mirror. The vacuum cavity contains a lens, a vacuum mirror, electrode plates, and micro / nano particles. After being focused by the lens, light beam A is redirected by 90° under the action of the vacuum mirror. The electrode plates are positioned along the optical path of light beam A after its redirection, and the micro / nano particles are located between the two electrode plates and can be captured by light beam A. After passing through the micro / nano particles, light beam A continues to propagate in its original direction, now carrying the state information of the micro / nano particles. It is then redirected again by 90° by another vacuum mirror, and after being completely collected by the lens, it leaves the vacuum cavity carrying the complete state information of the micro / nano particles. The beams are coupled to a four-quadrant detector outside the vacuum cavity, which acquires signals and transmits them to the control terminal. The optical axis of beam A entering the vacuum cavity is defined as the Z-axis. According to the right-hand rule, the two directions perpendicular to the Z-axis are defined as the X-axis and Y-axis, respectively. Beams B and C enter the vacuum cavity along the Y-axis or X-axis, respectively, to cool the micro-nano particles, and beams B and C enter the vacuum cavity in different directions. Beam D, after being reflected by a dichroic mirror, enters the vacuum cavity along the Z-axis together with beam A to cool the micro-nano particles.

2. The wavelength division multiplexing capture device for a single-beam vacuum optical trap according to claim 1, characterized in that, The optical power of the fiber laser is 0-5W, and the modulation optical power of the fiber acousto-optic modulator is 1-5W.

3. The wavelength division multiplexing capture device for a single-beam vacuum optical trap according to claim 1, characterized in that, The lens has a focal length of 75-300mm, the distance between the two electrode plates is 20-50mm, and the diameter of the micro-nano particles is 2-30μm.

4. The wavelength division multiplexing capture device for a single-beam vacuum optical trap according to claim 1, characterized in that, The optical fiber electro-optic modulator has a modulation optical power of 1W.

5. The wavelength division multiplexing capture device for a single-beam vacuum optical trap according to claim 1, characterized in that, The light beams A, B, C, and D enter the vacuum cavity through the vacuum cavity mirror on the vacuum cavity.

6. The wavelength division multiplexing capture device for a single-beam vacuum optical trap according to claim 1, characterized in that, The dichroic mirror exhibits near-complete transmission at a wavelength of 1064 nm and near-complete reflection at a wavelength of 532 nm.

7. A wavelength division multiplexing extremely weak force measurement method for a single-beam vacuum optical trap, implemented based on the wavelength division multiplexing capture device of the single-beam vacuum optical trap according to any one of claims 1-6, characterized in that, Specifically as follows: The fiber laser emits a 1064nm wavelength laser beam, which travels sequentially along the fiber through a fiber acousto-optic modulator and the first fiber beam splitter. One of the split beams travels along the fiber through a 1064nm fiber collimator to become a spatial light beam A. After being transmitted through a dichroic mirror, it enters the vacuum cavity horizontally. After passing through a lens to form a focused beam, beam A changes from a horizontal to a vertical state after passing through a vacuum mirror. It then passes through an electrode plate and acts on the micro-nano particles for capture. Simultaneously, beams B, C, and D enter the vacuum cavity in the X, Y, and Z directions, respectively, to perform triaxial cooling on the micro-nano particles. When micro-nano particles are captured, the vacuum chamber begins to operate, evacuating the cavity. When the vacuum level reaches a threshold, a four-phase detector collects signals and transmits them to the control terminal for data analysis. The micro-nano particle signal results are then fed back by a cooling mechanism, which modulates the light intensities of beams B, C, and D using an optical fiber electro-optic modulator, bringing the micro-nano particles into a stable capture state. At this point, a voltage is applied to the electrode plate, creating an electric field. As the electric field increases, the light intensity of beam A decreases until a balance between the electric field and gravity is achieved, capturing the micro-nano particles. The electric field at this equilibrium state is used as the measured value of the gravity of the micro-nano particles. After passing the micro-nano particles, the beam continues to propagate vertically, carrying the state of the micro-nano particles. After passing the reflector, the beam changes from vertical to horizontal again. After passing through the lens to collect complete information on the state of the micro-nano particles, it leaves the vacuum cavity and is coupled to the four-quadrant detector for signal acquisition and transmission to the control terminal. The control terminal obtains the signal containing the state of the micro-nano particles, thereby achieving precise measurement of extremely weak forces.

8. The wavelength division multiplexing extremely weak force measurement method for a single-beam vacuum optical trap according to claim 7, characterized in that, The micro-nano particles fall from above beam A via piezoelectric ceramic support and are captured in the optical trap trapping region where the focus of beam A is located.

9. The wavelength division multiplexing extremely weak force measurement method for a single-beam vacuum optical trap according to claim 7, characterized in that, The threshold value for the vacuum level within the vacuum chamber is 1x10. -6 mbar.

10. The wavelength division multiplexing extremely weak force measurement method for a single-beam vacuum optical trap according to claim 7, characterized in that, When micro- and nano-particles are in equilibrium under light-cooled high-vacuum conditions, the mass of the micro- and nano-particles... Where q is the charge, E is the electric field strength, and g is the gravitational acceleration.

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