CN108873171B - A multi-core fiber-like Bessel beam array optical tweezers - Google Patents

Abstract

A multi-core optical fiber Bessel beam array optical tweezers belongs to the technical field of optical trapping. The optical fiber comprises a multi-core optical fiber, a step multimode optical fiber and a laser light source, wherein a tail fiber of the laser light source is connected with one end of the multi-core optical fiber in a melting taper coupling mode, the other end of the multi-core optical fiber is in conventional coaxial fusion welding with one end of the step multimode optical fiber, and the other end of the step multimode optical fiber is prepared into an approximate semi-sphere structure with the radius R through melting processing. The invention relates to a novel all-fiber array optical tweezers based on Bessel-like light beams, which can be used for batch operation and screening of a plurality of tiny particles and realizes three-dimensional array arrangement of specific positions; the change of the quantity of the light potential well and the quantity of the captured particles can be realized by adjusting the number of the fiber cores of the multi-core fiber, the length of the step multimode fiber and the fused biconical taper shape of one end of the step multimode fiber, and the microscopic fine operation of the tiny particles is realized, so that the method has wide application value in the field of biomedical research.

Description

A multi-core fiber-like Bessel beam array optical tweezers

technical field

The invention belongs to the technical field of optical capture, and in particular relates to a multi-core optical fiber type Bessel beam array optical tweezers.

Background technique

Optical tweezers are tools for trapping and manipulating particles using the gradient force and scattering force of light intensity distribution. It was first proposed by Askin and his colleagues at Bell Labs in the United States in 1986 (Optics Letters, 18(5): 288-290, 1986), a three-dimensional optical potential well based on a single-beam laser, which is used to realize the detection of tiny particles. Three-dimensional control, so the light beam can realize the clamping of tiny particles in space, so it is named "optical tweezers". Since then, optical tweezers technology has developed rapidly and has become an important research technique, making it widely used in the field of manipulation of various tiny particles, ranging from particles of hundreds of microns to nanoparticles, from living cells to DNA biological macromolecular chains. Capture and manipulate with optical tweezers.

Because the traditional optical tweezers system is based on the optical microscope system, it is bulky, lacks flexibility in structure, and has less freedom of operation. As a waveguide medium, optical fiber is more suitable for micro-manipulation in complex space due to its flexible characteristics. Compared with conventional optical tweezers systems, fiber optic tweezers have been developed due to their simple structure, low price, and flexible operation.

Since the development of multi-fiber optical tweezers to array fiber optical tweezers technology, a variety of optical fiber optical tweezers systems have been produced. For example, in 2008, a publication entitled "Multi-optical tweezers integrated in a single fiber" was published with the publication number CN101251620. By adjusting the geometrical arrangement of the fiber core, the simultaneous capture of multiple tiny particles geometrically arranged at different positions can be achieved. At the same time, the capture performance of the optical tweezers has been greatly improved; in 2010, the publication number CN101893736A "Axial Array Optical Tweezers and Optical Dynamic Control Method Based on Array Core Fiber" was published one after another. The optical potential well formed at the end has a regular octahedral structure, and the optical potential well is formed at the vertex of the regular octahedron. By adjusting the driving circuit of the piezoelectric ceramic driving device, the direction displacement of the array core fiber is changed to control the phase of the transmitted beam, and the power distribution and adjustment are realized. Control the optical trap force distribution of the axial array optical tweezers; the publication number is CN101907742A "Array optical tweezers based on multi-core polarization-maintaining fibers and preparation method thereof", the array optical tweezers can form a dense interference grid at the fiber end The optical field array forms an optical potential well at the coherent enhancement point to screen particles and other functions. Most of these optical tweezers can achieve functions such as multi-particle capture operation, but there are few optical tweezers that can capture and operate three-dimensional arrays of sub-micron particles.

SUMMARY OF THE INVENTION

In view of the above-mentioned prior invention, the present invention provides a single-fiber array optical tweezers based on a fiber-like Bessel beam that realizes capture by a single-fiber three-dimensional array while saving physical space.

In order to achieve the above purpose, a multi-core fiber-like Bessel beam array optical tweezers disclosed in the present invention comprises a multi-core fiber (3), a step multi-mode fiber (2) and a laser light source (4), the laser light source (4). ) pigtail (41) is fused and taper-coupled to one end of the multi-core fiber (3), and the other end of the multi-core fiber (3) is conventionally coaxially spliced with one end of the step multimode fiber (2). The other end of the mode optical fiber (2) is prepared into an approximate hemispherical structure (22) with a radius R by melt processing.

The number of cores (31) of the multi-core optical fiber (3) is greater than or equal to 2, and the distribution of the cores (31) is not fixed.

The step multimode optical fiber (2) is a multimode optical fiber with a step refractive index distribution whose core diameter is greater than the core distance of the multi-core optical fiber, and the length of the step multimode optical fiber (2) is in the range of 200-500 μm and has an approximate hemispherical structure. The radius R of (22) is in the range of 50-90 μm.

By controlling the welding current time, the shape of the approximately hemispherical structure (22) is controlled.

The beneficial effects of the present invention are:

The invention is a new type of all-fiber array optical tweezers based on Bessel-like beams; the Bessel-like beams excited in the step-multimode fibers by coaxial fusion splicing of multi-core fibers and step-multimode fibers form a dense Three-dimensional optical potential wells can be used for batch operation and screening of multiple tiny particles to achieve three-dimensional array arrangement at specific positions; Bessel-like beam array optical tweezers based on multi-core fibers and step multi-mode fibers can be used for multi-core Adjustment of the number of fiber cores, the length of the step multimode fiber and the shape of the melting taper at one end of the step multimode fiber can realize the change of the number of optical potential wells and trapped particles, and realize the microscopic and fine operation of tiny particles, so that they can be used in biology. It has a wide range of application value in the field of medical research.

Description of drawings

Figure 1. Schematic diagram of the structure and principle of multi-core fiber-like Bessel beam array optical tweezers (taking five-core fiber as an example);

Figures 2(a)-(c) are cross-sectional views of multi-core optical fibers, wherein Figure 2(a) is a double-core, Figure 2(b) is a four-core, and Figure 2(c) is a five-core;

Figure 3 is a schematic diagram of a fiber probe of a multi-core fiber Bessel beam array optical tweezers;

Figure 4 is a schematic diagram of the coupling structure of the laser light source pigtail and the five-core optical fiber fusion taper.

Detailed ways:

The present invention will be further described below in conjunction with the accompanying drawings:

Example 1

A multi-core fiber-like Bessel beam array optical tweezers, comprising a multi-core fiber (3), a step multi-mode fiber (2) and a laser light source (4), a pigtail (41) of the laser light source (4) and a multi-mode fiber One end of the core optical fiber (3) is fused and taper-connected, the other end of the multi-core optical fiber (3) is conventionally coaxially spliced with one end of the stepped multimode optical fiber (2), and the other end of the stepped multimode optical fiber (2) is fused together. An approximate hemispherical structure (22) with a radius R is prepared by melt processing, and a laser light source (4) emits a laser to excite a Bessel-like beam (23) in the core (21) of the step multimode fiber (2), The hemispherical structure (22) converges the Bessel-like beams (23) and interferes in space to form an array of three-dimensional optical potential wells (24).

The number of cores (31) of the multi-core optical fiber (3) is greater than or equal to 2, and the distribution of the cores (31) is not fixed. (31) The distribution brings about different numbers and positions of optical traps.

The step multimode optical fiber (2) is a multimode optical fiber with a step refractive index distribution whose core diameter is greater than the core distance of the multi-core optical fiber, and the length of the step multimode optical fiber (2) is in the range of 200-500 μm and has an approximate hemispherical structure. (22) The range of the radius R is 50-90 μm. The length of the step multimode fiber and the shape of the melting taper at one end of the step multimode fiber are adjusted to realize the change of the optical potential well and the number of trapped particles, and realize the display of tiny particles. Micro fine operation.

By controlling the welding current time, the shape of the approximately hemispherical structure (22) is controlled.

The manufacturing process of a multi-core fiber-like Bessel beam array optical tweezers is as follows:

Step 1: Coupling the laser light source pigtail (41) with the five-core optical fiber (3) light source: using fusion taper coupling in combination with Figures 1 and 4, the laser light source pigtail (41) and the five-core optical fiber (3) are tapered Coupling to realize the coupling and distribution adjustment of the power of the laser light source (4).

Step 2, Bessel-like beam excitation: Combined with Fig. 1 and Fig. 3, in order to excite Bessel-like beam (23) in the step multimode fiber (2), the multi-core fiber (3) is combined with the step multimode fiber (2). The mode fiber (2) is conventionally coaxially spliced, and the step multimode length L is taken, and a Bessel-like beam (23) is excited in the step multimode fiber core (21).

Step 3, preparation of optical fiber cone-tip lens (22): with reference to FIG. 3, a hemispherical structure (22) with a radius of R is prepared by fusion processing to form a cone-tip lens, and the shape of the cone-tip lens is controlled by controlling the welding current time.

Step 4, three-dimensional array capture experiment: after the entire system is connected, turn on the light source (4), the laser light source is coupled into the multi-core fiber (3) through the taper region, the multi-core fiber (3) and the step multi-mode fiber (2) ) conventional coaxial fusion splicing, in which a Bessel-like beam (23) is excited in the stepped multimode fiber core (21), and the Bessel-like beam (23) is converged by the multimode fiber semicircular structure (22) The interference forms a three-dimensional optical potential well (24), so as to achieve the purpose of capturing tiny particles in a three-dimensional array.

Example 2

The invention relates to the field of optical capture, in particular to a multi-core fiber-like Bessel beam array optical tweezers.

Optical tweezers are tools for trapping and manipulating particles using the gradient force and scattering force of light intensity distribution. It was first proposed by Askin and his colleagues at Bell Labs in the United States in 1986 (Optics Letters, 18(5): 288-290, 1986), a three-dimensional optical potential well based on a single-beam laser, which is used to realize the detection of tiny particles. Three-dimensional control, so the light beam can realize the clamping of tiny particles in space, so it is named "optical tweezers". Since then, optical tweezers technology has developed rapidly and has become an important research technique, making it widely used in the field of manipulation of various tiny particles, ranging from particles of hundreds of microns to nanoparticles, from living cells to DNA biological macromolecular chains. Capture and manipulate with optical tweezers.

Because the traditional optical tweezers system is based on the optical microscope system, it is bulky, lacks flexibility in structure, and has less freedom of operation. As a waveguide medium, optical fiber is more suitable for micro-manipulation in complex space due to its flexible characteristics. Compared with conventional optical tweezers systems, fiber optic tweezers have been developed due to their simple structure, low price, and flexible operation.

Since the development of multi-fiber optical tweezers to array fiber optical tweezers technology, a variety of optical fiber optical tweezers systems have been produced. For example, in 2008, a publication entitled "Multi-optical tweezers integrated in a single fiber" was published with the publication number CN101251620. By adjusting the geometrical arrangement of the fiber core, the simultaneous capture of multiple tiny particles geometrically arranged at different positions can be achieved. At the same time, the capture performance of the optical tweezers has been greatly improved; in 2010, the publication number CN101893736A "Axial Array Optical Tweezers and Optical Dynamic Control Method Based on Array Core Fiber" was published one after another. The optical potential well formed at the end has a regular octahedral structure, and the optical potential well is formed at the vertex of the regular octahedron. By adjusting the driving circuit of the piezoelectric ceramic driving device, the direction displacement of the array core fiber is changed to control the phase of the transmitted beam, and the power distribution and adjustment are realized. Control the optical trap force distribution of the axial array optical tweezers; the publication number is CN101907742A "Array optical tweezers based on multi-core polarization-maintaining fibers and preparation method thereof", the array optical tweezers can form a dense interference grid at the fiber end The optical field array forms an optical potential well at the coherent enhancement point to screen particles and other functions. Most of these optical tweezers can achieve functions such as multi-particle capture operation, but there are few optical tweezers that can capture and operate three-dimensional arrays of sub-micron particles.

The purpose of the present invention is to provide a single-fiber array optical tweezers based on a fiber-like Bessel beam that realizes capture by a single-fiber three-dimensional array while saving physical space.

The object of the present invention is achieved in this way:

A multi-core fiber-like Bessel beam array optical tweezers, comprising a multi-core fiber (3) a step-by-step multi-mode fiber (2) and a laser light source (4), characterized in that: a pigtail (41) of the laser light source (4) ) is fused and taper-coupled to one end of the multi-core optical fiber (3), and the other end of the multi-core optical fiber (3) is conventionally coaxially spliced with the stepped multi-mode fiber (2). A Bessel-like beam (23) is excited in the core (21), and the other end of the step multi-mode optical fiber (2) with a certain length L is prepared into an approximate hemispherical structure (22) with a radius R by melting and processing, and the semicircular The spherical structure (22) converges the Bessel-like beams (23) and interferes in space to form an array of three-dimensional optical potential wells (24).

The number of cores (31) of the multi-core optical fiber (3) is greater than or equal to two.

The step multimode fiber (2) is a multimode fiber with a step refractive index distribution whose core diameter is greater than the core distance of the multi-core fiber. 22) The radius R may be 50-90 μm.

The pigtail of the laser light source (4) is fused and taper-coupled with one end of the multi-core optical fiber (3), so as to realize power coupling and distribution adjustment.

The advantages and characteristics of the present invention are:

demonstrated a novel all-fiber array optical tweezers based on Bessel-like beams;

A compact three-dimensional optical potential well is formed by coaxially splicing a multi-core fiber and a step multi-mode fiber, and the Bessel-like beam excited in the step multi-mode fiber interferes. 3D array arrangement at a specific location;

Bessel-like beam array optical tweezers based on multi-core fiber and step multi-mode fiber can be adjusted by adjusting the number of multi-core fiber cores, the length of the step multi-mode fiber, and the shape of the fused taper at one end of the step multi-mode fiber. It can realize the change of the number of optical potential wells and trapped particles, and realize the microscopic and fine operation of tiny particles, which makes it have a wide range of application value in the field of biomedical research.

The present invention will be discussed in more detail below in conjunction with the accompanying drawings:

The purpose of the present invention is to provide a single-fiber array optical tweezers based on a fiber-like Bessel beam that realizes capture by a single-fiber three-dimensional array while saving physical space. This single-fiber array optical tweezers demonstrates a new type of all-fiber array optical tweezers based on Bessel-like beams; at the same time, it can be used for batch operation and screening of multiple tiny particles to achieve a three-dimensional array arrangement at a specific location, making it It has a wide range of application value in the field of biomedical research.

A multi-core fiber-like Bessel beam array optical tweezers, comprising a multi-core fiber (3) a step-by-step multi-mode fiber (2) and a laser light source (4), characterized in that: a pigtail (41) of the laser light source (4) ) is fused and taper-coupled to one end of the multi-core optical fiber (3), and the other end of the multi-core optical fiber (3) is conventionally coaxially spliced with the stepped multi-mode fiber (2). A Bessel-like beam (23) is excited in the core (21), and the other end of the step multi-mode optical fiber (2) with a certain length L is prepared into an approximate hemispherical structure (22) with a radius R by melting and processing, and the semicircular The spherical structure (22) converges the Bessel-like beams (23) and interferes in space to form an array of three-dimensional optical potential wells (24).

The number of cores (31) of the multi-core optical fiber (3) is greater than or equal to two.

The step multimode optical fiber (2) is a multimode optical fiber with a step refractive index distribution whose core diameter is greater than the core distance of the multi-core optical fiber. The radius R of the spherical structure (22) may be 50-90 μm.

The pigtail of the laser light source (4) is fused and taper-coupled with one end of the multi-core optical fiber (3), so as to realize power coupling and distribution adjustment.

Figure 1 is a schematic diagram of the structure and principle of a multi-core fiber-like Bessel beam array optical tweezers (taking a five-core fiber as an example). Among them, (1) is a single-fiber Bessel-like array optical tweezers that can realize array capture, (2) is a large-core step multimode fiber, (3) is a multi-core fiber, (4) is a laser light source, and (22) ) is a hemispherical lens of radius R made by melting. One end of the pigtail fiber of the laser light source (4) and the multi-core optical fiber (3) are coupled by fusion taper, and the other end of the multi-core optical fiber (3) is conventionally coaxially spliced with the step multi-mode fiber (2) to excite the step multi-mode fiber. In the Bessel-like beam, the Bessel-like beam forms an array optical trap through spatial interference of a hemispherical lens (22) at one end of the step multimode fiber, and finally realizes three-dimensional array capture.

Figures 2(a)-(c) are cross-sectional views of multi-core optical fibers, wherein Figure 2(a) is a double-core, Figure 2(b) is a four-core, and Figure 2(c) is a five-core. The distribution of the fiber cores can be symmetrical or asymmetrical, and different core distributions bring about different numbers and positions of optical traps.

FIG. 3 is a schematic diagram of a fiber probe of a multi-core fiber Bessel beam array optical tweezers. The multicore fiber (2) is conventionally coaxially spliced with the step multimode fiber (3) to excite Bessel-like beams in the step multimode. The fiber length of the step multimode (3) is L, and the other end of the fiber is fused to form a hemispherical lens (22) with a radius R, and the Bessel-like beams converge and interfere in space through the spherical lens to form an array optical trap.

Figure 4 is a schematic diagram of the coupling structure of the laser light source pigtail and the five-core optical fiber fusion taper. The coupling and distribution adjustment of the power of the laser light source (4) can be realized through the fusion taper coupling.

The single-fiber Bessel-like optical tweezers ( 1 ) for realizing such three-dimensional array capture with reference to FIG. 1 mainly include a multi-core optical fiber ( 3 ), a step-step multi-mode optical fiber ( 2 ) and a laser light source ( 4 ). The pigtail (41) of the laser light source (4) is connected to one end of the multi-core optical fiber (3) by fusion and taper fusion, and the other end of the multi-core optical fiber (3) is conventionally coaxially spliced with the step multi-mode optical fiber (2). A Bessel-like beam (23) is excited in the core (21) of the step multimode fiber (2), and the other end of the step multimode fiber (2) is melt-processed to prepare a hemispherical structure with a radius R ( 22), by converging Bessel-like beams (23) through a hemispherical structure (22) and interfering in space to form an array of three-dimensional optical potential wells (24).

The manufacturing process of the single-fiber optical tweezers of this embodiment:

Step 1: Coupling the laser light source pigtail (41) with the five-core optical fiber (3) light source: using fusion taper coupling in combination with Figures 1 and 4, the laser light source pigtail (41) and the five-core optical fiber (3) are tapered Coupling to realize the coupling and distribution adjustment of the power of the laser light source (4).

Step 2, Bessel-like beam excitation: Combined with Fig. 1 and Fig. 3, in order to excite Bessel-like beam (23) in the step multimode fiber (2), the multi-core fiber (3) is combined with the step multimode fiber (2). The mode fiber (2) is conventionally coaxially spliced, and the step multimode length L is taken, and a Bessel-like beam (23) is excited in the step multimode fiber core (21).

Step 3, preparation of optical fiber cone-tip lens (22): with reference to FIG. 3, a hemispherical structure (22) with a radius of R is prepared by fusion processing to form a cone-tip lens, and the shape of the cone-tip lens is controlled by controlling the welding current time.

Step 4, three-dimensional array capture experiment: after the entire system is connected, turn on the light source (4), the laser light source is coupled into the multi-core fiber (3) through the taper region, the multi-core fiber (3) and the step multi-mode fiber (2) ) conventional coaxial fusion splicing, in which a Bessel-like beam (23) is excited in the stepped multimode fiber core (21), and the Bessel-like beam (23) is converged by the multimode fiber semicircular structure (22) The interference forms a three-dimensional optical potential well (24), so as to achieve the purpose of capturing tiny particles in a three-dimensional array.

Claims (1)

1. The utility model provides a multicore optic fibre class Bessel beam array optical tweezers, includes multicore optic fibre (3), step multimode fiber (2) and laser source (4), its characterized in that: a tail fiber (41) of a laser light source (4) is connected with one end of a multi-core fiber (3) in a fused biconical coupling mode, the other end of the multi-core fiber (3) is conventionally and coaxially welded with one end of a step multimode fiber (2) with a certain length, a Bessel-like light beam is excited in the step multimode fiber, the other end of the step multimode fiber (2) is prepared into an approximate semi-spherical structure (22) with a radius R through fusion processing, and the Bessel-like light beam is converged through the semi-spherical structure to form a multi-point array three-dimensional potential well (24) through interference in space;

the number of fiber cores (31) of the multi-core optical fiber (3) is more than or equal to 2, the distribution of the fiber cores (31) is not fixed, and different fiber core (31) distribution brings different light traps in number and positions;

the step multimode fiber (2) is a multimode fiber with the core diameter larger than the core distance of the multi-core fiber and the step refractive index distribution, and the length range of the step multimode fiber (2) is 200-500 mu m so as to form a compact space multi-point array three-dimensional potential well;

the shape of the approximate semi-sphere structure (22) of the semi-sphere lens is controlled by controlling the welding current time, and the radius R of the semi-sphere structure (22) ranges from 50 to 90 mu m.

And the tail fiber of the laser light source (4) is fused and tapered with one end of the multi-core fiber to be coupled, so that the power coupling and distribution adjustment are realized.

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