Optical fiber riffle system for particle directional ejection and control method
Technical Field
The invention relates to an optical fiber riffle system for directionally ejecting particles, and belongs to the technical field of micro-manipulation of optical tweezers.
Background
The traditional micro-fluidic analysis system transports and directionally moves particles and cells by adding electrodes at two ends of a container loaded with the particles and the cells, polarizes the particles and the cells, and transports the particles and the cells towards the direction of an electric field under the action of the electric field force of the electrodes at the two ends after polarization, thereby achieving the effect of transporting the particles and the cells. This method with electrodes also has a relatively small effect on the particles, but a relatively large effect on the cells, which if subjected to voltage may affect the cell tissue and even destroy the cell wall. The operation of directional movement of cells in organisms is very many, so that another control method with less damage or even no damage to biological tissues is urgently needed to be found.
The interaction between the light beam and the particle transfers the momentum of the light beam to the particle, causing the particle to be captured, rotated, and transported. These manipulation methods have opened up a range of tools that use light to micromanipulate particles. Astro standing waves et al propose a light gun for directional emission of particles (Deng, Hongchang, et al. "Fiber-based optical gun for particle shooting." ACS Photonics 4.3(2017):642-648 "). The optical gun adopts a coaxial double-waveguide optical fiber with an annular core and an intermediate core, the fiber end of the optical gun is provided with a cone frustum structure for reflecting and focusing, the annular light beam can be focused to form the optical tweezers, the capture of particles is realized, and the ejection of the particles is realized by Gaussian light energy output by the intermediate core. However, since the beam output from the intermediate core is a diverging gaussian beam, the scattering forces acting on the particles may cause the particles to deviate from the axial direction of the fiber, thereby causing the particles to deviate from the intended motion profile. This light gun structure can be analogized to the shotgun in the actual firearm, which is short in range and lacks precision in hitting the target.
In fact, in the development of firearms, rifles have been proposed to increase the range and improve the accuracy of hitting the target. The rifling in the barrel of such a gun imparts a spinning force to the cartridge and therefore has a higher accuracy and a longer range than a smoothbore gun. By analogy with this, in order to increase the distance of directional transport of the particles and the accuracy of the transport path, a rotational momentum may be imparted to the particles before they are emitted.
The photo-induced rotation is an effective means for realizing the rotation of the particles, and the following methods are mainly adopted for realizing the light-driven rotation so far: the first way is to use spin angular momentum to achieve rotation (Hill-autumn-silk, Ziyanying, Schwann, etc.. use a beam with spin angular momentum to achieve rotation of the particles [ J ]. Chinese laser, 2008,35(10): 324-; the second way is to achieve rotation using orbital angular momentum (Gaomingwei, high spring, what dawn swallow, etc.. the rotation of particles is achieved using a light beam with orbital angular momentum [ J ]. Physics, 2004,53(2): 413-417.); the third way is to use the linear momentum of light to realize rotation, design and manufacture micro devices with specific shape structure, and use the interaction of reflection, refraction, absorption, etc. of light beam by the devices to realize rotation of the devices (Galajda P, Ormos P. complex micro technologies Produced and drive by light, applied. Phys. Lett.2001, 78 (2): 249-.
Disclosure of Invention
The invention aims to provide a fiber-optic riffle system for directionally ejecting particles and a control method of the system.
The purpose of the invention is realized as follows:
an optical fiber riffle system for particle directional ejection is disclosed, as shown in figure 1, and comprises a three-channel light source 1, a first optical fiber coupler 2-1, a second optical fiber coupler 2-2, a first adjustable optical fiber attenuator 3-1, a second adjustable optical fiber attenuator 3-2, an optical fiber phase modulator 4, a three-core optical fiber fanning-in device 5, a three-core optical fiber 6, a coaxial double-wave optical fiber fanning-in device 7, a coaxial double-wave optical fiber 8 and a fiber end cone round platform 9, wherein the input end of the first optical fiber coupler 2-1 is connected with one output channel 1-1 of the three-channel light source, and a plurality of divided optical paths are connected with a ring-shaped core input channel of the coaxial double-wave optical fiber fanning-in device 7 and used for injecting a capture beam into the ring-core of the coaxial double-wave optical fiber 8; the input end of the second optical fiber coupler 2-2 is connected with one output channel 1-2 of the three-channel light source, the output end is divided into two paths, wherein one path is connected with a first fiber core channel of the three-core optical fiber fanning-in device 5 after being connected with the first adjustable optical fiber attenuator 3-1 and the optical fiber phase modulator 4, and the other path is connected with a second fiber core channel of the three-core optical fiber fanning-in device 5 after being connected with the second adjustable optical fiber attenuator 3-2; a third fiber core channel of the three-core optical fiber fanning-in device 5 is directly connected with a third output channel 1-3 of the three-channel light source; the three-core optical fiber 6 is correspondingly connected with the middle core of the coaxial double-waveguide optical fiber 8 after passing through the coaxial double-waveguide optical fiber fanning-in device 7.
As shown in FIG. 2, the coaxial double waveguide fiber 8 has a cladding, an intermediate core 8-1 and a ring core 8-2, wherein the intermediate core 8-1 is a few-mode core, preferably, the intermediate few-mode core is a three-mode core, supporting two LP cores in orthogonal orientation11Mold and LP01And (5) molding.
The fiber end of the coaxial double-waveguide fiber is provided with a cone frustum 9 for reflecting and focusing the captured light beam transmitted in the annular core 8-2, and the reflection surface of the fiber end can improve the reflectivity by plating a metal film.
Preferably, the first optical fiber coupler 2-1 is a 1 × 6 uniform light splitting single-mode optical fiber coupler, in order to uniformly inject the trapped light waves into the annular core 8-2;
preferably, the second optical fiber coupler 2-2 is a 1 × 2 uniform light splitting single-mode optical fiber coupler;
as shown in fig. 3, the three-core optical fiber 6 includes an outermost fluorine-doped low-refractive-index cladding, a pure silica cladding, and three single-mode cores 6-1 to 6-3 having different mode field effective refractive indices in a triangular distribution.
The structure of the coaxial dual-waveguide optical fiber fanning-in device 7 is shown in fig. 4, and the specific preparation method is as follows:
step 1: six double-clad optical fibers 11 and one three-core optical fiber 6 are taken, a fluorine-doped seven-hole sleeve 13 is inserted after coating layers are stripped, the cross section of the seven-hole sleeve 13 is shown in figure 5, and the sleeve is a fluorine-doped quartz tube with low refractive index. Wherein the three-core optical fiber 6 is inserted into the middle hole of the seven-hole sleeve 13, and the six double-clad optical fibers 11 are inserted into six peripheral holes of the seven-hole sleeve.
Step 2: and (3) cutting the combined sleeve at a proper cone waist under high temperature to obtain a seven-core cone output end face 14, wherein the middle core of the output end face 14 is a three-mode multiplexer formed by tapering the three-core optical fiber 6, and six fiber cores on the periphery are single-mode fiber cores formed by tapered inner cladding after tapering the six double-clad optical fibers 11. The geometrical spacing distribution of seven cores at the output end is consistent with the core distribution of the coaxial double-waveguide fiber 8. In addition, the end face of the double-clad optical fiber 11 used is shown in fig. 6 and comprises a single-mode core 11-1, an inner cladding 11-2 and an outer cladding, and after the optical fiber is adiabatically tapered, the optical wave in the core is gradually adiabatically transited into the inner cladding for transmission, and the mode field distribution is kept unchanged. The input end of the double-clad fiber 11 is connected to a single-mode fiber 12.
And step 3: and (3) welding the taper obtained by cutting in the step (2) with the coaxial double-waveguide fiber (8), wherein: the six double-clad optical fibers are correspondingly connected with the annular core 8-2 of the coaxial double-waveguide optical fiber after tapering, the three-core optical fiber 6 is correspondingly connected with the middle few mold cores 8-1 of the coaxial double-waveguide optical fiber, and the fiber core mode division multiplexer is formed.
And 4, step 4: and packaging the device to obtain the coaxial double-wave optical fiber fanning-in device 7.
As shown in fig. 7, the three-core fiber fanning-in device 5 has three single-mode fibers 12 as input ends, and the output ends respectively correspond to three single-mode fiber cores of the three-core fiber 6. Preferably, the three-core fiber fanning-in device 5 is also prepared by a double-clad fiber bundle tapering method. The concrete description is as follows: and (3) welding single-mode fibers 12 at one ends of three double-clad fibers 11, stripping the coating at the other ends of the three double-clad fibers, inserting the coating into a three-hole quartz sleeve 15, thermally insulating, tapering, cutting, and performing core-to-core welding with the three-core fibers 6 to form the fanning-in device 5 of the three-core fibers.
The control method of the directional particle ejection comprises the following steps:
(1) referring to fig. 1, a first output channel 1-1 of a three-channel light source 1 provides capture light, the capture light is split by a first optical fiber coupler 2-1, injected into an annular core 8-2 of a coaxial double-waveguide optical fiber 8 through a coaxial double-waveguide optical fiber fanning-in device 7, reflected and focused by a fiber end cone frustum 9, and forms a three-dimensional capture mechanical potential well to stably capture particles 10.
(2) A second output channel 1-2 of the three-channel light source 1 is divided into two paths by a second optical fiber coupler 2-2, and the two paths correspondingly form two orthogonal LP (Low-pass) of a middle core 8-1 of a coaxial double-waveguide optical fiber 8 after passing through a three-core optical fiber fanning-in device 5 and a coaxial double-waveguide optical fiber fanning-in device 611Mode, two light beams are adjusted by adjusting two variable optical attenuators 3-1 and 3-2 and a fiber phase modulator 4The input intensity and phase difference causes the output of the intermediate core 8-1 of the final coaxial double waveguide fiber 8 to be in a vortex optical mode for trapping the fixed axis rotation of the particles 10.
(3) A third output channel 1-3 of the three-channel light source 1 correspondingly forms a fundamental mode of a coaxial double-wave light guide fiber intermediate core 8-1 after passing through a three-core optical fiber fanning-in device 5 and a coaxial double-wave light guide fiber fanning-in device 7, the light beam generates forward radiation pressure on the captured particles 10 and can eject the particles 10 forward, and the ejecting force of the particles 10 can be adjusted by adjusting the output power of the channel.
In summary, by the control adjustment described above, the rotational emission of the fine particles can be realized.
Compared with the prior art, the invention has the following characteristics:
the invention adopts special coaxial double-waveguide fiber, realizes the omnibearing three-dimensional stable capture of particles by utilizing the focusing of annular light beams transmitted in an annular core, realizes the fixed-axis rotation of captured particles by combining the photoinduced rotation function of vortex light, and realizes the directional ejection of the particles by using Gaussian light beams with proper intensity. The rotary directional ejection can realize longer range and higher transmission precision.
Drawings
FIG. 1 is a block diagram of a fiber optic riffle system for directed ejection of particles.
FIG. 2 is an end view and refractive index profile of a coaxial dual waveguide fiber.
Fig. 3 is an end view of a three-core optical fiber.
Fig. 4 is a structural diagram of a coaxial two-wave optical fiber fanning-in device.
Fig. 5 is an end view of a fluorine-doped seven-hole casing.
FIG. 6 is an end view and refractive index profile of a double-clad optical fiber.
Fig. 7 is a block diagram of a three-core fiber fan-in device.
FIG. 8 shows the mode field distributions of the three modes supported by the intermediate core of a coaxial double waveguide fiber, where (a) is LP01The basic mode, (b) and (c) are LP11And (5) molding.
Fig. 9 to 12 show that the input conditions of different cores of the middle three-core fiber of the coaxial dual-waveguide fiber fanning-in device correspond to different output modes of the middle core of the coaxial dual-waveguide fiber.
FIG. 13 is a schematic diagram of the cone frustum structure of a coaxial dual waveguide fiber and the operation of a riffle.
Detailed Description
The invention is further illustrated below with reference to specific examples.
Such as the fiber optic riflescope system for directional ejection of particles shown in fig. 1. The optical fiber sensing device comprises a three-channel light source 1, a first optical fiber coupler 2-1, a second optical fiber coupler 2-2, a first adjustable optical fiber attenuator 3-1, a second adjustable optical fiber attenuator 3-2, an optical fiber phase modulator 4, a three-core optical fiber fanning-in device 5, a three-core optical fiber 6, a coaxial double-wave optical fiber fanning-in device 7, a coaxial double-waveguide optical fiber 8 and a fiber end cone round table 9, wherein the input end of the first optical fiber coupler 2-1 is connected with one output channel 1-1 of the three-channel light source, and a plurality of branched optical paths are connected with an annular core input channel of the coaxial double-wave optical fiber fanning-in device 7 and used for injecting a capture light beam into an annular core of the coaxial double-wave optical fiber 8; the input end of the second optical fiber coupler 2-2 is connected with one output channel 1-2 of the three-channel light source, the output end is divided into two paths, wherein one path is connected with a first fiber core channel of the three-core optical fiber fanning-in device 5 after being connected with the first adjustable optical fiber attenuator 3-1 and the optical fiber phase modulator 4, and the other path is connected with a second fiber core channel of the three-core optical fiber fanning-in device 5 after being connected with the second adjustable optical fiber attenuator 3-2; a third fiber core channel of the three-core optical fiber fanning-in device 5 is directly connected with a third output channel 1-3 of the three-channel light source; the three-core optical fiber 6 is correspondingly connected with the middle core of the coaxial double-waveguide optical fiber 8 after passing through the coaxial double-waveguide optical fiber fanning-in device 7.
The three-channel light source 1 selects an LD laser with the wavelength of 976 nm; the middle core 8-1 of the coaxial double-waveguide fiber 8 is a three-mode fiber core, and the supported mode is LP01Mode and two orthogonal LPs11The mode field distributions are shown in fig. 8(a) to (c).
The mode division multiplexer of the coaxial double-waveguide fiber intermediate core 8-1 is formed by tapering a three-core fiber 6, each fiber core of the three-core fiber correspondingly excites one mode in fig. 8, and the corresponding relation is shown in fig. 9-11.
The power and phase of light waves in the fiber cores of the three-core optical fibers 6-1 and 6-2 are adjusted by adjusting the two variable optical attenuators 3-1 and 3-2 and the optical fiber phase modulator 4 in the system, so that the first-order vortex rotation can be combined in the coaxial double-waveguide optical fiber intermediate core 8-1, as shown in FIG. 12.
Fig. 13 shows the structure of the taper frustum 9 at the fiber end of the coaxial dual-waveguide fiber 8 and the operation principle of the riffle. The trapping light beam injected into the annular core 8-2 can trap the single yeast cell 10, and then the middle core 8-1 of the coaxial double waveguide fiber 8 outputs vortex rotation by adjusting, so that the trapped yeast cell 10 rotates in a fixed axis mode. Then inputting LP through a 6-3 fiber core channel of the three-core optical fiber01Mode, the yeast cells 10 are ejected in a rotational orientation.
In the description and drawings, there have been disclosed typical embodiments of the invention. The invention is not limited to these exemplary embodiments. Specific terms are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth.