A three-dimensional decoupling control device and method for optical tweezers focal position

Abstract

The present invention discloses a three-dimensional decoupling control device and method for optical tweezers focus position, relating to the field of optical tweezers array control. The device comprises: an arbitrary waveform generator (AWG) for generating a radio frequency (RF) signal that matches the target optical tweezers motion trajectory; four signal amplifiers, each connected to the output of the AWG for amplifying the RF signal; two pairs of orthogonally arranged acousto-optic deflectors (AODs), each with its input interface connected to the output of the four signal amplifiers; a 4f lens group, disposed between the two pairs of AODs, for relaying the light beam and achieving phase conjugation; and an objective lens, disposed behind the second pair of AODs, for focusing the modulated light beam to the target position. The device achieves active decoupling of radial beam deflection and axial focusing through the phase conjugation design of a cascaded AOD and a 4f lens group. Combined with a fully electronic focusing mechanism and FPGA real-time processing, the device significantly improves the precision, speed, and stability of three-dimensional optical tweezers control.

Description

Technical Field

[0001] The present invention relates to the field of optical tweezers array control, and more particularly to a device and method for controlling the three-dimensional decoupling of optical tweezers focal positions. Background Art

[0002] The three-dimensional manipulation technology of neutral atom optical tweezers arrays is an important foundation in the fields of quantum computing and quantum precision measurement. Its core goal is to use laser optical tweezers to perform high-precision and high-speed three-dimensional control of atomic positions in order to build large-scale, stable three-dimensional atomic arrays.

[0003] Traditional solutions use an acousto-optic deflector (AOD) combined with an electrically controlled zoom lens to achieve three-dimensional manipulation through the coordination of two-dimensional radial displacement and one-dimensional axial movement. However, the low response bandwidth of a mechanical zoom lens limits the axial movement speed. Furthermore, the strong coupling between radial displacement and the axial potential well depth causes atomic heating during movement, severely destabilizing the array's trapped stability and making it difficult to meet the requirements of high-precision multi-dimensional manipulation.

[0004] The solution based on spatial light modulator (SLM) controls the three-dimensional position of the optical tweezers through dynamic wavefront coding, but its refresh rate is low and high-speed scanning cannot be achieved. In addition, the pixel unit size limitation of SLM (such as 10μm-level phase modulation period) leads to a decrease in diffraction efficiency during axial movement and a significant deterioration in the spot quality, which affects the capture efficiency of the optical tweezers and the reliability of atomic manipulation.

[0005] None of the above solutions can achieve high speed, high precision, and three-dimensional decoupled control. The inertial delay of mechanical focusing and the refresh limit of the SLM restrict dynamic response capabilities, while the coupling effect of radial-axial motion further exacerbates control errors, making the system difficult to adapt to the needs of complex three-dimensional trajectory tracking or the efficient rearrangement of large-scale atomic arrays.

[0006] Therefore, how to design a three-dimensional decoupling control device for the focal position of optical tweezers that can eliminate the coupling of radial and axial motions and achieve high-speed and high-precision three-dimensional decoupling control of optical tweezers manipulation is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a three-dimensional decoupling control device and method for the focal position of optical tweezers. Through the phase conjugation design of the cascaded AOD and the fully electronic focusing mechanism, the decoupling control of the three-dimensional optical tweezers position is realized, effectively solving technical problems such as axial and radial coupling, slow axial movement speed, and high system complexity and cost, thereby improving the accuracy, speed and stability of optical tweezers manipulation.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a three-dimensional decoupling control device for optical tweezers focal position, comprising:

[0010] An arbitrary waveform generator, used to generate a radio frequency signal that matches the target optical tweezers motion trajectory;

[0011] four signal amplifiers, respectively connected to the output ends of the arbitrary waveform generator, for amplifying the radio frequency signal;

[0012] Two pairs of orthogonally arranged acousto-optic deflectors, each with its input interface connected to the output of four signal amplifiers. The first pair of acousto-optic deflectors includes AOD1 and AOD2, and the second pair includes AOD3 and AOD4. AOD1 and AOD3 are used to deflect and focus the light beam in the X direction, while AOD2 and AOD4 are used to deflect and focus the light beam in the Y direction.

[0013] The 4f lens group is placed between the two pairs of acousto-optic deflectors to relay the light beam and achieve phase conjugation.

[0014] The objective lens is arranged behind the second pair of acousto-optic deflectors and is used to focus the modulated light beam to a target position.

[0015] Preferably, a real-time signal processor is further included, which is used to realize dynamic superposition of driving signals through FPGA programming and control the radio frequency signal output by the arbitrary waveform generator.

[0016] Preferably, the acousto-optic deflector uses tellurium dioxide as the acoustic material, has an operating light wavelength of 532 nm, a sound speed of 650 m / s, a maximum scanning angle of 41 mrad, a center frequency of 80 MHz, and an operating frequency range of 50 MHz.

[0017] Preferably, the 4f lens group includes a pair of lenses, the distance between the lenses is twice the focal length, and the distance between the lenses and the adjacent acousto-optic deflector is one focal length, and the focal length reference value is 10 cm.

[0018] Preferably, the objective lens has an equivalent focal length of 10 mm, and is directly connected to the second pair of acousto-optic deflectors by adjacent installation, or is indirectly connected to the second pair of acousto-optic deflectors by means of a reflector and a relay optical path.

[0019] In a second aspect, the present invention provides a method for three-dimensional decoupling control of the optical tweezers focus position, comprising: 1) axial displacement of the optical tweezers focus:

[0020] A linear frequency modulation signal is synchronously input to the first pair of acousto-optic deflectors AOD1 and AOD3 and the second pair of acousto-optic deflectors AOD2 and AOD4, wherein the instantaneous frequency of the linear frequency modulation signal satisfies:

[0021]

[0022] Where f0 represents the initial frequency and α represents the frequency modulation slope;

[0023] The 4f lens group relays the light beam and realizes the phase conjugate optical path. The acousto-optic lens effects of AOD1 and AOD3, and AOD2 and AOD4 are superimposed to generate an equivalent focal length:

[0024]

[0025] Where v is the speed of sound and λ is the laser wavelength;

[0026] Adjust the frequency modulation slope α to dynamically control the equivalent focal length F, and achieve the displacement of the optical tweezers focus along the Z-axis in the direction of beam propagation;

[0027] 2) Radial displacement of the optical tweezers focus:

[0028] For X-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD1 and AOD3; for Y-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD2 and AOD4;

[0029] The acousto-optic lens effect is offset by the phase conjugate path, and the Bragg diffraction deflection effect is superimposed to generate the deflection angle:

[0030]

[0031] Where f is the frequency difference between AOD1 and AOD3, or AOD2 and AOD4;

[0032] By adjusting the frequency modulation slope α and the signal timing, the displacement of the optical tweezers focus on the X-axis and Y-axis can be achieved.

[0033] It can be seen from the above technical solution that compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0034] 1. This technical solution uses a phase conjugate design of two pairs of orthogonally arranged acousto-optic deflectors and a 4f lens group to achieve active decoupling of radial beam deflection and axial focusing at the optical level. This avoids displacement interference caused by mechanical or wavefront modulation in traditional solutions and significantly improves control accuracy and stability.

[0035] 2. A fully electronic focusing mechanism based on an acousto-optic deflector, combined with FPGA real-time signal processing, breaks through the bandwidth limitations of traditional mechanical zoom lenses or SLMs, enabling high-speed three-dimensional movement of optical tweezers and continuous tracking of complex trajectories, significantly improving the efficiency of atomic array manipulation.

[0036] 3. Through the relay optical path design of the 4f lens group and the compact integration of the objective lens, while ensuring the phase conjugate optical path, the beam distortion is effectively suppressed and high spot quality is maintained, achieving high diffraction efficiency and low light loss at a large scanning angle, ensuring the spot quality of the optical tweezers focus and the stability of the system in complex experimental environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 A schematic structural diagram of a three-dimensional decoupling control device for optical tweezers focal position provided by an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the axial displacement implementation process provided by an embodiment of the present invention;

[0040] Figure 3 A schematic diagram of the radial displacement implementation process provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Example 1;

[0043] like Figure 1 As shown, this embodiment provides a three-dimensional decoupling control device for the focus position of optical tweezers, comprising:

[0044] An arbitrary waveform generator, used to generate a radio frequency signal that matches the target optical tweezers motion trajectory;

[0045] four signal amplifiers, respectively connected to the output ends of the arbitrary waveform generator, for amplifying the radio frequency signal;

[0046] Two pairs of orthogonally arranged acousto-optic deflectors, each with its input interface connected to the output of four signal amplifiers. The first pair of acousto-optic deflectors includes AOD1 and AOD2, and the second pair includes AOD3 and AOD4. AOD1 and AOD3 are used to deflect and focus the light beam in the X direction, while AOD2 and AOD4 are used to deflect and focus the light beam in the Y direction.

[0047] The 4f lens group is placed between the two pairs of acousto-optic deflectors to relay the light beam and achieve phase conjugation.

[0048] The objective lens is arranged behind the second pair of acousto-optic deflectors and is used to focus the modulated light beam to a target position.

[0049] and a real-time signal processor, which is used to realize dynamic superposition of driving signals through FPGA programming and control the radio frequency signal output by the arbitrary waveform generator.

[0050] The following is a further detailed description of each structure of the above device:

[0051] The acousto-optic deflector uses tellurium dioxide as the acoustic material, with an operating light wavelength of 532nm, a sound velocity of 650m / s, a maximum scanning angle of 41mrad, a center frequency of 80MHz, and an operating frequency range of 50MHz. This material has high diffraction efficiency (>80%) and low optical loss, ensuring high-speed deflection and focusing stability.

[0052] Furthermore, the 4f lens group includes a pair of lenses with a distance of twice the focal length between the lenses and a distance of one focal length between the adjacent acousto-optic deflector. The focal length reference value is 10 cm. This design achieves phase conjugation of the light beam through precise optical path relay, eliminating the coupling effect of axial and radial motion.

[0053] Furthermore, the objective lens has an equivalent focal length of 10 mm and is directly connected to a second pair of acousto-optic deflectors through adjacent installation, or indirectly connected to the second pair of acousto-optic deflectors through a reflector and a relay optical path, to ensure high-quality focusing of the optical tweezers focus; the relay optical path here is composed of two lenses with a spacing of twice the focal length, which is used to maintain the phase conjugation of the light beam and the quality of the light spot.

[0054] The design principle of the phase conjugate optical path of the above device is:

[0055] After the first pair of AODs (AOD1 / AOD2) deflects and focuses the beam in the X / Y directions, they relay the beam to the second pair of AODs (AOD3 / AOD4) via a 4f lens system. The phase-conjugated configuration of the two AOD pairs superimposes the beam deflection directions, canceling out the acousto-optic lensing effect, or canceling out the deflection directions and superimposing the lensing effects, achieving active decoupling of radial displacement from axial focusing.

[0056] Furthermore, a real-time signal processor programmed with FPGA is used to dynamically superimpose linear frequency modulation and scanning signals to control the AOD driving frequency.

[0057] This device solves the radial-axial coupling problem in traditional optical tweezers systems through the phase conjugation design of cascaded AOD pairs and the optical path optimization of the 4f lens group. Based on tellurium dioxide acousto-optic devices and FPGA real-time control, it achieves high-speed, high-precision three-dimensional decoupling control of the optical tweezers focus. Its fully electronic architecture and compact optical path design provide an efficient and stable atomic array manipulation platform for the field of precision measurement.

[0058] Example 2;

[0059] This embodiment provides a three-dimensional decoupling control method for optical tweezers focus position, including:

[0060] like Figure 2 As shown, the axial displacement of the optical tweezers focus is:

[0061] A linear frequency modulation signal is synchronously input to the first pair of acousto-optic deflectors AOD1 and AOD3 and the second pair of acousto-optic deflectors AOD2 and AOD4, wherein the instantaneous frequency of the linear frequency modulation signal satisfies:

[0062]

[0063] Wherein, f0 represents the initial frequency, α represents the frequency modulation slope; specifically, the value range of f0 is 75-85MHz, with a typical value of 80MHz; the value range of α is 0 to 10 12 Hz / s, corresponding to the axial coordinate 0 to about 251.8um, and the displacement resolution is less than 5um;

[0064] The 4f lens group relays the light beam and realizes the phase conjugate optical path. The acousto-optic lens effects of AOD1 and AOD3, and AOD2 and AOD4 are superimposed to generate an equivalent focal length:

[0065]

[0066] Where v is the speed of sound and λ is the laser wavelength;

[0067] Adjust the frequency modulation slope α and dynamically control the equivalent focal length F to achieve the displacement of the optical tweezers focus along the Z axis of the beam propagation direction; finally, the optical tweezers are imaged through the objective lens and are located behind the objective lens. The focus is at , and the displacement in z direction is , is the focal length of the objective lens.

[0068] like Figure 3 As shown, the radial displacement of the optical tweezers focus is:

[0069] For X-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD1 and AOD3; for Y-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD2 and AOD4;

[0070] The acousto-optic lens effect is offset by the phase conjugate path, and the Bragg diffraction deflection effect is superimposed to generate the deflection angle:

[0071]

[0072] Where f is the frequency difference between AOD1 and AOD3, or AOD2 and AOD4;

[0073] By adjusting the frequency modulation slope α and the signal timing, the displacement of the optical tweezers focus on the X-axis and Y-axis can be achieved.

[0074] Furthermore, complex movement of the optical tweezers focus in three-dimensional space is achieved by superimposing radial (X / Y axis) and axial (Z axis) drive signals. The control functions f1(t) and f2(t) for radial and axial displacements correspond to different frequency modulation slope combinations: radial control uses inverse frequency modulation slopes to offset lensing and superimpose deflection, while axial control uses synchronized frequency modulation slopes to enhance the lensing effect. By optimizing the timing and parameters of the two sets of drive signals, the radial and axial degrees of freedom are decoupled in the temporal domain, enabling high-speed continuous motion of the optical tweezers focus along an arbitrary three-dimensional trajectory.

[0075] This embodiment achieves fully decoupled control of the radial (X / Y-axis) and axial (Z-axis) motion of the optical tweezers focus through cascaded acousto-optic deflectors and a phase-conjugated optical path design. The optical tweezers focus can continuously move along arbitrary trajectories in three-dimensional space at high speeds, surpassing the speed and precision limitations of mechanical focusing and wavefront encoding. This provides efficient three-dimensional decoupled control for applications such as atomic array rearrangement and single-molecule manipulation.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. References to the same or similar parts between the various embodiments are sufficient. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For relevant parts, refer to the method description.

[0077] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-dimensional decoupling control device for optical tweezers focal position, characterized in that: include: An arbitrary waveform generator, used to generate a radio frequency signal that matches the target optical tweezers motion trajectory; four signal amplifiers, respectively connected to the output ends of the arbitrary waveform generator, for amplifying the radio frequency signal; Two pairs of orthogonally arranged acousto-optic deflectors, each with its input interface connected to the output of four signal amplifiers. The first pair of acousto-optic deflectors includes AOD1 and AOD2, and the second pair includes AOD3 and AOD4. AOD1 and AOD3 are used to deflect and focus the light beam in the X direction, while AOD2 and AOD4 are used to deflect and focus the light beam in the Y direction. The 4f lens group is placed between the two pairs of acousto-optic deflectors to relay the light beam and achieve phase conjugation. an objective lens, disposed behind the second pair of acousto-optic deflectors, for focusing the modulated light beam to a target position; The control method under the control device includes: 1) Axial displacement of the optical tweezers focus: A linear frequency modulation signal is synchronously input to the first pair of acousto-optic deflectors AOD1 and AOD3 and the second pair of acousto-optic deflectors AOD2 and AOD4, wherein the instantaneous frequency of the linear frequency modulation signal satisfies: Where f0 represents the initial frequency and α represents the frequency modulation slope; The 4f lens group relays the light beam and realizes the phase conjugate optical path. The acousto-optic lens effects of AOD1 and AOD3, and AOD2 and AOD4 are superimposed to generate an equivalent focal length: Where v is the speed of sound and λ is the laser wavelength; Adjust the frequency modulation slope α and dynamically control the equivalent focal length F to achieve the displacement of the optical tweezers focus along the Z axis of the beam propagation direction; after the objective lens imaging, the optical tweezers are behind the objective lens. Focus on is the focal length of the objective lens; 2) Radial displacement of the optical tweezers focus: For X-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD1 and AOD3; for Y-axis displacement, linear scanning signals with opposite frequency modulation slopes are input to AOD2 and AOD4; The acousto-optic lens effect is offset by the phase conjugate path, and the Bragg diffraction deflection effect is superimposed to generate the deflection angle: Where f is the frequency difference between AOD1 and AOD3, or AOD2 and AOD4; By adjusting the frequency modulation slope α and the signal timing, the displacement of the optical tweezers focus on the X-axis and Y-axis can be achieved.

2. The optical tweezers focus position three-dimensional decoupling control device according to claim 1, characterized in that: It also includes a real-time signal processor for realizing dynamic superposition of driving signals through FPGA programming and controlling the radio frequency signal output by the arbitrary waveform generator.

3. The optical tweezers focus position three-dimensional decoupling control device according to claim 1, characterized in that: The acousto-optic deflector uses tellurium dioxide as the acoustic material, has an operating light wavelength of 532nm, a sound speed of 650m / s, a maximum scanning angle of 41mrad, a center frequency of 80MHz, and an operating frequency range of 50MHz.

4. The optical tweezers focus position three-dimensional decoupling control device according to claim 1, characterized in that: The 4f lens group includes a pair of lenses, the distance between the lenses is twice the focal length, and the distance between the lenses and the adjacent acousto-optic deflector is one focal length, and the focal length reference value is 10 cm.

5. The optical tweezers focus position three-dimensional decoupling control device according to claim 1, characterized in that: The objective lens has an equivalent focal length of 10 mm and is directly connected to the second pair of acousto-optic deflectors through adjacent installation, or is indirectly connected to the second pair of acousto-optic deflectors through a reflecting mirror and a relay optical path.

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