Single-mode circular truncated cone optical fiber tweezers for capturing nanoparticles based on LP11 mode

Abstract

The invention belongs to the technical field of optical fibers, and particularly relates to single-mode circular truncated cone optical fiber tweezers for capturing nanoparticles based on an LP11 mode, the single-mode circular truncated cone optical fiber tweezers comprise a first single-mode optical fiber, a second single-mode optical fiber is fixed at one end of the first single-mode optical fiber, the first single-mode optical fiber is connected with the second single-mode optical fiber in a core staggering manner, and the second single-mode optical fiber is fixed at the other end of the first single-mode optical fiber. A tapered optical fiber pigtail is arranged at one end, far away from the first single-mode optical fiber, of the second single-mode optical fiber; the preparation method comprises the following steps: S1, cutting a section of first single-mode fiber and a section of second single-mode fiber for later use, S2, stripping a coating layer from one end of the second single-mode fiber, S3, grinding one end of the second single-mode fiber, and S4, carrying out core staggering connection on the first single-mode fiber and the second single-mode fiber. The capturing radius is further improved, so that the capturing precision and the capturing radius of the single-fiber optical tweezers are improved, and the manufacturing difficulty of the single-fiber optical tweezers is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of optical fiber technology and specifically relates to a method based on LP 11 Single-mode frustum-cone fiber tweezers for trapping nanoparticles. Background Art

[0002] Optical tweezers is a technology that uses the radiation pressure generated by laser beams to manipulate and manipulate tiny particles, molecules, and even cells. The technology was first proposed by American scientist Ashkin and his colleagues in 1986, and a related paper was published in the journal Optical Letters. The core of optical tweezers technology lies in the radiation pressure of light, that is, when a light beam passes through a medium, the momentum of the light beam changes due to refraction or reflection, thereby generating radiation pressure. At the focus of the light beam, there are two main forces: gradient force and scattering force. The gradient force attracts objects to the point where the intensity of the light beam is the highest, while the scattering force tends to push the object away. By precisely controlling these two forces, stable capture and manipulation of tiny objects can be achieved.

[0003] The advantage of optical tweezers technology lies in its non-contact manipulation method, which makes it have important applications in the biomedical field. Since the light beam can penetrate biological particles without causing mechanical damage to them, optical tweezers are particularly suitable for in vivo operations, such as the manipulation of cells, organelles and biomolecules. In addition, optical tweezers technology can accurately apply tiny forces, which is very suitable for studying nano- and micro-scale particles, as well as the mechanical properties of biological particles.

[0004] In the field of biology, optical tweezers technology has been used to study DNA macromolecules, proteins, and the interaction between molecules. For example, optical tweezers can be used to manipulate cells, study their mechanical properties, and even study molecular dynamics within cells. In the fields of physics and chemistry, optical tweezers technology provides new tools for studying micromechanics and particle manipulation.

[0005] In a study published in 2014, Zhang Yu et al. from Harbin Engineering University proposed a method based on LP 11 The single-mode optical tweezers technology can stimulate LP in single-mode optical fiber through a specific optical fiber core welding method. 11 This method can achieve various manipulations of particles, including capture, rotation, and axial movement, by precisely controlling the amount of optical fiber core misalignment and modifying the optical fiber tip through selective chemical etching and discharge current melting technology. 11 The mode beam converges inside the optical fiber tip to form a nanometer-scale capture light trap. Compared with the traditional chemical etching or heating and melting cone technology, this method improves the capture radius and capture accuracy of the target particles, and has low cost and simple structure, providing more practical application possibilities in the field of biomedical research.

[0006] However, the capture radius of the target particles in the above paper is still small, and thus cannot stably capture nanometer-sized particles. Therefore, it is necessary to propose a new type of single-mode frustum fiber tweezers. Summary of the invention

[0007] The purpose of the present invention is to provide a method based on LP 11 The single-mode truncated cone fiber tweezers used to capture nanoparticles have further improved their capture radius, thereby increasing the capture accuracy and capture radius of the single-fiber tweezers while also reducing the difficulty of making the single-fiber tweezers.

[0008] The technical solution adopted by the present invention is as follows:

[0009] Based on LP 11 The single-mode frustum optical tweezers used for capturing nanoparticles include a first single-mode optical fiber, one end of which is fixed with a second single-mode optical fiber;

[0010] The first single-mode optical fiber is connected to the second single-mode optical fiber in a staggered manner, and a tapered optical fiber pigtail is provided at one end of the second single-mode optical fiber away from the first single-mode optical fiber.

[0011] The offset between the first single-mode optical fiber and the second single-mode optical fiber is 2 μm.

[0012] The output wavelength of the first single-mode optical fiber is 980 nm.

[0013] The cutoff wavelength of the second single-mode optical fiber is 1310 nm.

[0014] The included angle between the second single-mode optical fiber and the tapered optical fiber pigtail is 22°.

[0015] The core refractive index of the first single-mode optical fiber and the second single-mode optical fiber are both 1.4661, and the cladding refractive index are both 1.457.

[0016] Based on LP 11 Method for preparing single-mode truncated cone optical fiber tweezers for capturing nanoparticles The method is used to prepare the above-mentioned single-mode truncated cone optical fiber tweezers, and the preparation method comprises the following steps:

[0017] S1: firstly, cut off a section of the first single-mode optical fiber and a section of the second single-mode optical fiber for standby use;

[0018] S2: Then, stripping the coating layer of one end of the second single-mode optical fiber, cutting it evenly, and then cleaning the end face of the second single-mode optical fiber (1-2);

[0019] S3: then grinding one end of the second single-mode optical fiber to form the tapered optical fiber pigtail;

[0020] S4: Finally, the first single-mode optical fiber and the second single-mode optical fiber are connected by staggered core connection, and the tapered optical fiber pigtail is located at an end away from the first single-mode optical fiber.

[0021] In S4, the first single-mode optical fiber and the second single-mode optical fiber are connected by fusion splicing.

[0022] The technical effects achieved by the present invention are:

[0023] The present invention has further improved the capture radius by staggering the cores of a 980nm single-mode optical fiber and a 1310nm single-mode optical fiber to stimulate the LP 11 mode light field, and by combining with a simple grinding method to modify the optical fiber end method, the capture accuracy of the optical fiber tweezers is simply and effectively improved; the present invention improves the capture accuracy and capture radius of the single-fiber optical tweezers while reducing the difficulty of making the single-fiber optical tweezers. The device used is low in price and the preparation method is simple, which is suitable for promotion in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of single-mode truncated cone optical fiber tweezers in the present invention;

[0025] Figure 2 is a schematic diagram of the overall fiber optic tweezers system of the present invention;

[0026] Figure 3 It is a schematic diagram of the optical fiber grinder grinding a tapered optical fiber in the present invention.

[0027] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0028] 1-1, first single-mode optical fiber; 1-1-1, single-mode optical fiber core; 1-2, second single-mode optical fiber; 1-3, tapered optical fiber pigtail; 1-3-1, light beam; 1-3-2, capture light trap; 1-3-3, end face; 2-1, laser light source; 2-2, optical fiber fusion welding machine; 2-3, staggered core fusion; 2-4, three-dimensional adjustment frame; 2-5, first optical fiber probe; 2-6, sample pool; 2-7, irradiation light source; 2-8, optical microscope; 2-9, computer; 3-1, rotation; 3-2, sand tray; 3-3, sandpaper; 3-4, second optical fiber probe; 3-5, four-dimensional adjustment frame. DETAILED DESCRIPTION

[0029] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0030] A LP-based 11 The single-mode frustum fiber tweezers used to capture nanoparticles are single-mode frustum fiber tweezers that can combine mode excitation and light shaping technology. And the fiber tweezers can not only excite high-order modes LP 11 The outgoing light beam can also form a capture light trap 4-4 that can stably capture nano-sized particles based on the fiber shaping. This achieves the goal of studying smaller biological particles in the biological field. The fiber optic tweezers proposed by this method are low-cost and simple in structure, providing many possibilities for more practical applications in the field of biomedical research.

[0031] The manufacturing process of the implementation method is described in detail with reference to the accompanying drawings:

[0032] Embodiment 1:

[0033] See attached Figure 1 , including a first single-mode optical fiber 1-1, the output wavelength of the first single-mode optical fiber 1-1 is 980nm, a second single-mode optical fiber 1-2 is fixed at one end of the first single-mode optical fiber 1-1, the cutoff wavelength of the second single-mode optical fiber 1-2 is 1310nm, the core refractive index of the first single-mode optical fiber 1-1 and the second single-mode optical fiber 1-2 are both 1.4661, and the refractive index of the cladding is both 1.457;

[0034] The 9980nm laser light source 2-1 is connected to the 980nm single-mode optical fiber core 1-1-1 to form a semicircular LP with symmetry at both ends at the exit end face of the second single-mode optical fiber 1-2 at 1310nm. 11 Mode beam 1-3-1, to ensure the formation of a stable optical potential well capable of capturing nano-sized particles;

[0035] The first single-mode optical fiber 1-1 is connected to the second single-mode optical fiber 1-2 by core misalignment. According to the difference in the misalignment between the first single-mode optical fiber 1-1 and the second single-mode optical fiber 1-2, the generated LP 11 The light field effect of the end face of the mode output beam is also different. Through experimental observation, when the misalignment between the first single-mode optical fiber 1-1 and the second single-mode optical fiber 1-2 is approximately 2μm, LP 11 The two sub-beams 1-3-1 of the mode light beam tend to be perfectly symmetrical, thus forming an effective fiber optic tweezers that can capture nano-sized particles, and a tapered fiber pigtail 1-3 is provided at one end of the second single-mode fiber 1-2 away from the first single-mode fiber 1-1. The angle between the second single-mode fiber 1-2 and the tapered fiber pigtail 1-3 is 22°. In order to ensure that the light beam can converge onto the fiber end face after total reflection in the single-mode fiber, a suitable grinding depth needs to be selected. In addition, in the tapered fiber probe area, as the grinding depth increases, the LP 11The mode beam will also be more affected by its cone angle, which will cause the generated light trap to be unstable. Through experimental observation, when the reserved length of the end face 1-3-3 is about 4μm, a stable light trap that can capture nano-scale particles can be formed;

[0036] Through the above settings, the capture radius of the fiber tweezers is further improved; the LP is stimulated by staggered connection of the first single-mode fiber 1-1 with a wavelength of 980 nm and the second single-mode fiber 1-2 with a wavelength of 1310 nm. 11 The mode light field and the capture accuracy of the fiber tweezers are simply and effectively improved by combining with a simple grinding method to modify the fiber end.

[0037] Therefore, the present invention improves the capture accuracy and capture radius of the single-fiber optical tweezers while reducing the difficulty of manufacturing the single-fiber optical tweezers. The device used is low-priced and the preparation method is simple, which is suitable for promotion in the biomedical field.

[0038] Embodiment 2:

[0039] See attached Figure 2 and attached Figure 3 , a method based on LP 11 A method for preparing single-mode truncated cone optical fiber tweezers for capturing nanoparticles is provided. The method is used to prepare the above-mentioned single-mode truncated cone optical fiber tweezers. The preparation method comprises the following steps:

[0040] S1: First, a section of the 980nm first single-mode optical fiber 1-1 and a section of the 1310nm second single-mode optical fiber 1-2 are cut for standby use;

[0041] S2: Then, one end of the second single-mode optical fiber 1-2 is stripped of a coating layer of about 2 cm using a wire stripper, and the coating layer is cut evenly, and then an alcohol non-woven cloth with alcohol is used to wipe the end face of the second single-mode optical fiber 1-2 to ensure that the end face is clean and free of pollution;

[0042] S3: Then fix the second optical fiber probe 3-4 on the four-dimensional adjustment frame 3-5. The four-dimensional adjustment frame 3-5 can shape the optical fiber into a suitable shape by making the optical fiber rotate autonomously and the turntable and the optical fiber rotate relative to each other. After fixing the optical fiber, use CCD for observation. With its help, grind one end of the second single-mode optical fiber 1-2 and form a tapered optical fiber pigtail 1-3. At the same time, in order to ensure that the light beam can converge the light spot on the optical fiber end face after total reflection in the single-mode optical fiber, it is also necessary to select a suitable grinding depth. In the tapered optical fiber probe area, as the grinding depth increases, LP 11 The mode beam will also be affected by its cone angle, which will cause the generated light trap to be unstable. Therefore, it is necessary to observe whether its grinding depth is around 4μm. 11Under the action of the tapered pigtail 1-3 that has been ground and modified by the grinder, the mode light beam converges at the front section of the optical fiber and forms two capture light traps 1-3-2 with a scale of nanometers, thereby stably capturing nano-scale particles near the optical fiber probe;

[0043] Combination Figure 3 , which is a process diagram of using a fiber optic grinder to grind the optical fiber. According to the principle of total reflection, the grinding angle is calculated. The 1310nm ordinary single-mode optical fiber needs to be grinded to a suitable angle, which is about 22°. First, the 1310nm second single-mode optical fiber 1-2 is fixed by a four-dimensional adjustment frame 3-5; the optical fiber is controlled to contact the fiber optic grinder 3-2 at an angle of about 22°. At this time, the optical fiber is grinded by replacing sandpaper 3-3 with different roughness to achieve the expected optical fiber structure shape;

[0044] Then, start the spin to make the optical fiber spin, and then turn on the grinder sand disc 3-2 to rotate 3-1, and shape the optical fiber together with the optical fiber spin. Observe through the CCD to prevent the second single-mode optical fiber 1-2 from being damaged. After a specific time, modify the end face of the optical fiber to make it conical. Then replace the sandpaper 3-3 with a smaller roughness and repeat the above steps for polishing, and continue to observe under the perspective of the CCD until the roughness of the tapered area of ​​the optical fiber is small enough to affect the formation of the total reflection angle of the optical fiber, and the optical fiber shaping part is completed. After the shaping is completed, use a microscope to observe the tip of the optical fiber to observe whether its tapered angle meets the capture requirements. In order to reduce the loss and interference caused by the reflection of the optical fiber end face, the grinding angle of the 1310nm second single-mode optical fiber 1-2 needs to be greater than the total reflection angle, and theoretical analysis shows that under the same incident power laser, the closer the grinding angle is to the total reflection angle, the greater the capture force of the nano-light trap it generates;

[0045] S4: After the 1310nm second single-mode optical fiber 1-2 is polished and shaped, the outgoing light field at the tip of the optical fiber is observed using a CCD. A 980nm laser is introduced, and when the excited LP 11 When the two sub-beams 1-3-1 of the mode light beam tend to be perfectly symmetrical, the first single-mode optical fiber 1-1 and the second single-mode optical fiber 1-2 are staggered-core-fused 2-3 using an optical fiber fusion welding machine 2-2, and the tapered optical fiber pigtail 1-3 is located at one end away from the first single-mode optical fiber 1-1.

[0046] The following is an embodiment of the steps of using the above-mentioned fiber optic tweezers in the present application, as follows:

[0047] Select a certain amount of nano-particle PS particles and use an appropriate amount of water to prepare them. After adding the particles to the solvent, adapt to ultrasonic treatment for oscillation to ensure that the particles are evenly dispersed. Store the prepared solution under appropriate conditions, avoiding light and temperature changes to maintain the stability of the particles. And in the whole process, pay attention to avoid the generation of bubbles to ensure the dispersion of the particles and the uniformity of the solution;

[0048] Use the sample pool 2-6 and the irradiation light source 2-7 to hit the sample pool 2-6, and adjust the focus through the optical microscope 2-8, and accurately control the position of the fiber optic probe through the three-dimensional adjustment frame 2-4 and the micro-operation console. Pass the 980nm laser light source 2-1 to form LP 11 After the shape of the fiber optic probe can be clearly seen in the CCD, the configured nano-scale particle 100nm polystyrene particle solution is dripped onto the hydrophobic glass slide in an appropriate amount, and the focal length is continuously adjusted until the shape of the fiber tip can be clearly observed. Finally, the speed of the three-dimensional adjustment frame 2-4 is slowed down and the three-dimensional adjustment frame 2-4 is precisely controlled to control the position of the first fiber optic probe 2-5 to observe whether the nanoparticles are captured. After the particles are stably captured, the three-dimensional adjustment frame 2-4 is continuously adjusted to control the position of the first fiber optic probe 2-5 and ensure that the nano-scale particles are stably captured. After the prepared fiber optic probe is introduced with a 980nm laser, it is placed in a solution containing nano-particles to accurately capture the nano-particles. At the same time, the image is collected by CCD and stored by the computer 2-9. For the first time, the grinding technology and the beam mode change technology are combined together, and a smaller capture light trap is produced, so that nano-scale particles can be stably captured.

[0049] The specific capture steps are:

[0050] The laser emits a fiber body through a staggered welding structure to achieve a 980nm first single-mode fiber 1-1 and a 1310nm second single-mode fiber 1-2 welding, so that the fiber body passes through the fiber cone and generates LP 11 The light beam receives incident light, captures particles through the light trap on it, obtains captured particles, and then captures the particles under a microscope through a probe and transmits them to a computer for imaging.

[0051] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. Based on LP 11 The single-mode frustum-cone optical tweezers used for capturing nanoparticles are characterized by: It comprises a first single-mode optical fiber (1-1), wherein a second single-mode optical fiber (1-2) is fixed to one end of the first single-mode optical fiber (1-1); The first single-mode optical fiber (1-1) and the second single-mode optical fiber (1-2) are connected in a staggered manner, and a tapered optical fiber pigtail (1-3) is provided at one end of the second single-mode optical fiber (1-2) away from the first single-mode optical fiber (1-1).

2. The single-mode truncated cone optical tweezers according to claim 1, characterized in that: The offset between the first single-mode optical fiber (1-1) and the second single-mode optical fiber (1-2) is 2 μm.

3. The single-mode truncated cone optical tweezers according to claim 1, characterized in that: The output wavelength of the first single-mode optical fiber (1-1) is 980 nm.

4. The single-mode truncated cone optical tweezers according to claim 1, characterized in that: The cutoff wavelength of the second single-mode optical fiber (1-2) is 1310 nm.

5. The single-mode truncated cone optical tweezers according to claim 1, characterized in that: The included angle between the second single-mode optical fiber (1-2) and the tapered optical fiber pigtail (1-3) is 22°.

6. The single-mode truncated cone optical tweezers according to claim 1, characterized in that: The core refractive index of the first single-mode optical fiber (1-1) and the second single-mode optical fiber (1-2) are both 1.4661, and the refractive index of the cladding are both 1.

457.

7. Based on LP 11 A method for preparing a single-mode truncated cone optical fiber tweezers for capturing nanoparticles, characterized in that: The method is used to prepare the single-mode truncated cone fiber tweezers according to any one of claims 1 to 6, and the preparation method comprises the following steps: S1: firstly, cutting off a section of the first single-mode optical fiber (1-1) and a section of the second single-mode optical fiber (1-2) for standby use; S2: then stripping the coating layer of one end of the second single-mode optical fiber (1-2), cutting it evenly, and then cleaning the end face of the second single-mode optical fiber (1-2); S3: then grinding one end of the second single-mode optical fiber (1-2) to form the tapered optical fiber pigtail (1-3); S4: Finally, the first single-mode optical fiber (1-1) and the second single-mode optical fiber (1-2) are connected in a staggered manner, and the tapered optical fiber pigtail (1-3) is located at an end away from the first single-mode optical fiber (1-1).

8. The preparation method according to claim 7, characterized in that: In S4, the first single-mode optical fiber (1-1) and the second single-mode optical fiber (1-2) are connected by fusion splicing.

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