CN103792665A - Beam shaping device based on microfluidic optical technology - Google Patents

Abstract

A beam shaping device based on microfluidic optical technology, including a fluid optical waveguide body, an incident laser, a beam receiving surface, and an outflow fluid reservoir. The fluid optical waveguide body is opened with a flow channel for carrying microfluids. The flow channel includes a The core layer fluid inlet, two symmetrical cladding fluid inlets, the fluid microcavity and two symmetrical fluid outlets, the core fluid inlet and the cladding fluid inlet are all connected to the inlet side of the fluid microcavity, and the outlet side of the fluid microcavity It is connected with two fluid outlets, the fluid outlet communicates with the outflow fluid reservoir, the incident laser and the beam receiving surface are coaxially arranged, the axes of the incident laser and the beam receiving surface intersect with the fluid flow direction axis, and the incident laser and the beam receiving surface The surface is placed symmetrically with the intersection point as the center of symmetry, and the beam propagation direction and the fluid flow direction are 90°±10°. The invention has the advantages of small loss in the light propagation process, simplified structure, convenient manufacture and good control flexibility.

Description

Beam shaping device based on microfluidic optical technology

technical field

The invention relates to the field of optical devices and detection systems, in particular to a light beam shaping device. Background technique

Beam shaping technology includes focusing, collimation, deflection, beam splitting, coupling and other adjustments to the beam, usually by adjusting the dielectric constant and permeability distribution of the optical medium and then changing the spatial electromagnetic field distribution, such as for optical devices The adjustment of the refractive index distribution can easily realize the control of focusing, collimation, deflection, and beam splitting of the incident beam. The rapid development of microfluidic optical technology in recent years has provided us with a new method of beam shaping. The principle is to control the microscopic scale of light by controlling the flow of fluid. In view of this, microfluidic technology and systems can be introduced into the design and fabrication of fluid optical waveguides with controllable refractive index. If a fluid with a higher refractive index can diffuse in a fluid with a lower refractive index, and can achieve a stable distribution during the diffusion process, then there will be a controllable flow in the process of fluid diffusion and convection. Refractive index distribution, for example, using etching technology to fabricate microfluidic channels on the substrate material, combined with a constant flow fluid device, can realize microfluidic graded refractive index distribution lenses based on convection and diffusion effects (Mao X, Lin SS, Lapsley MI, Shi J, Juluri BK, Tunable liquid gradient refractive index (L-GRIN) lens with two degrees of freedom, Lab.Chip., 9(2009):2050-2058, tunable with 2 degrees of freedom adjustment ability Liquid graded-index lenses, Lab on a Chip, 9(2009):2050-2058; Yang Y, Liu AQ, Chin LK, Zhang XM, Tsai DP, Lin CL, Lu C, Wang GP, Zheludev NI, Optofluidic waveguide as a transformation Optics device for lightwave bending and manipulation, Nat.Commun., 3(2012):651-657 ). To use microfluidic optics technology to achieve dynamic beam shaping, the beam shaping method based on microfluidic optics technology and the fluid optical waveguide structure based on this method are the core technical problems that must be solved.

Contents of the invention

In order to overcome the deficiencies of the existing beam shaping methods, such as large loss in light propagation process, complex structure, difficult production, and poor control flexibility, the present invention provides a light transmission process based on low loss, simplified structure, convenient production, and good control flexibility. Beam shaping device for microfluidic optics.

The technical solution adopted by the present invention to solve its technical problems is:

A beam shaping device based on microfluidic optical technology, comprising a fluid optical waveguide main body, an incident laser, a beam receiving surface and an outflow fluid reservoir, the fluid optical waveguide main body is provided with a flow channel for carrying microfluids, the The flow channel comprises a core fluid inlet, two symmetrical cladding fluid inlets, a fluid microcavity and two symmetrical fluid outlets, the core fluid inlet and the cladding fluid inlet are all connected to the inlet side of the fluid microcavity The outlet side of the fluid microcavity is connected to two fluid outlets, the fluid outlet is communicated with the outflow fluid reservoir, the incident laser and the beam receiving surface are coaxially arranged, the incident laser and the beam The axis of the receiving surface intersects the axis of the fluid flow direction, the incident laser and the beam receiving surface are symmetrically placed with the intersection point as the center of symmetry, and the incident laser injects a laser beam of a set wavelength into the fluid optical waveguide, and the beam The direction of propagation is 90°±10° to the direction of fluid flow, and the beam receiving surface receives the output beam after passing through the fluid optical waveguide.

Further, the beam propagation direction is perpendicular to the fluid flow direction, and the beam receiving surface is coaxial with the incident laser.

The beam shaping device also includes a peristaltic pump for injecting fluid. The peristaltic pump for injecting fluid is located at the inlet of the core layer fluid and the inlet of the cladding fluid. The adjustment of the flow rate of the fluid is realized by controlling the peristaltic pump, and the adjustment of the flow rate of the fluid is realized by controlling the peristaltic pump. The regulation of the temperature of the fluid.

The technical idea of the present invention is to dynamically control the refractive index of the waveguide by utilizing the diffusion and convection process of the core layer and the cladding fluid that constitute the fluid optical waveguide. There are many factors that affect the diffusion and convection process of the two fluids, such as temperature, concentration, and flow rate. As well as the selection of the type of microfluid, the structure and size of the main body of the fluid optical waveguide, and then affect the distribution of the refractive index. In a finite-length microchannel, if the fluid velocity is high and the diffusion of the core fluid is limited, then the convective effect dominates. At this time, the fluid optical waveguide can be approximately regarded as a step refractive index distribution (perpendicular to the fluid flow direction ) waveguide structure; and when the fluid flow rate is low, the diffusion effect is obvious. At this time, whether it is the cross-sectional direction of the microcavity or along the fluid flow direction, the influence of the diffusion effect on the concentration gradient must be considered, while the core fluid is in the cladding layer The diffusion in the fluid is the theoretical basis for the realization of the graded-index fluid optical waveguide. Therefore, the process of diffusion and convection can be effectively controlled by controlling the flow rate and fluid type of the core fluid and cladding fluid, thereby controlling the spatial distribution of fluid diffusion concentration and refractive index.

The beneficial effects of the present invention are mainly manifested in: 1. Based on the beam shaping method of microfluidic optical technology, the fluid optical waveguide structure is formed by the convection and diffusion process between the two fluids, by controlling the flow velocity of the core layer and the cladding fluid and Fluid types can obtain flexible and variable refractive index distributions; 2. By inventing fluid optical waveguides based on microfluidic optical technology, new devices that can focus, collimate, split, and deflect light beams can be constructed; 3. The dynamic adjustment of beam focusing, beam splitting and deflection is realized, and it belongs to online real-time adjustment; 4. The beam propagation direction is perpendicular to the fluid flow direction, which effectively reduces the propagation loss of the beam.

Description of drawings

Fig. 1 is a schematic diagram of a beam shaping device based on microfluidic optical technology of the present invention.

Fig. 2 is a schematic diagram of the cavity of the fluid optical waveguide body carrying the microfluid in the beam shaping device based on the microfluidic optical technology of the present invention.

Fig. 3 is the distribution of refractive index at different cross-sections of the fluidic optical waveguide of the present invention along the direction of fluid flow.

Figure 4 shows the distribution of the refractive index at the cross section at the center position along the fluid flow direction (that is, where the laser beam is incident) at different flow rates.

Figure 5 shows the distribution of the refractive index at the cross section at the center of the fluid flow direction (that is, where the laser beam is incident) when the flow velocity of the cladding on one side is changed when the flow velocity of the cladding on both sides is different.

Fig. 6 is the variation of the refractive index distribution of the fluid optical waveguide with the flow velocity when the refractive index of the cladding fluid is higher than that of the core fluid.

Detailed ways

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

Referring to Figures 1 to 6, a beam shaping method based on microfluidic optics technology, the shaping method uses a beam shaping device based on microfluidic optics technology, the beam shaping device includes a fluid optical waveguide body 1, an incident laser 2 , a light beam receiving surface 3 and an outflow fluid reservoir 4, the fluid optical waveguide main body 1 is provided with a channel for carrying microfluidics, and the channel includes a core fluid inlet 5 and two symmetrical cladding fluid inlets 6. The fluid microcavity 7 and two symmetrical fluid outlets 8, the core layer fluid inlet 5 and the cladding fluid inlet 6 are all communicated with the inlet side of the fluid microcavity 7, and the outlet side of the fluid microcavity 7 Connected with two fluid outlets 8, the fluid outlet 8 communicates with the outflow fluid reservoir 4, the incident laser 2 and the beam receiving surface 3 are coaxially arranged, and the axes of the incident laser and the beam receiving surface are in line with the The axes of the fluid flow directions intersect, and the incident laser and the beam receiving surface are symmetrically placed with the intersection point as the center of symmetry. The direction is 90°±10°, and the beam receiving surface receives the output beam after passing through the fluid optical waveguide.

Further, the beam propagation direction is perpendicular to the fluid flow direction, and the beam receiving surface is coaxial with the incident laser.

The beam shaping device also includes a peristaltic pump for injecting fluid. The peristaltic pump for injecting fluid is located at the inlet of the core layer fluid and the inlet of the cladding fluid. The adjustment of the flow rate of the fluid is realized by controlling the peristaltic pump, and the adjustment of the flow rate of the fluid is realized by controlling the peristaltic pump. The regulation of the temperature of the fluid.

In the beam shaping device of this embodiment, the beam shaping method implemented includes the following steps:

(1) There is only diffusion and convection between the core fluid and the cladding fluid (the core fluid and the cladding fluid do not chemically react with each other), and the cladding fluid surrounds the core fluid in a balanced manner, so The core fluid and the cladding fluid are two fluids with different refractive indices, and the core fluid and the cladding fluid flow in the fluid microcavity to jointly form a fluid optical waveguide;

(2) The incident laser injects the laser beam with a set wavelength into the fluid optical waveguide, the beam propagation direction is 90°±10° with the fluid flow direction, and the beam receiving surface receives the output beam after passing through the fluid optical waveguide ;

(3) By adjusting the fluid flow rate, temperature, concentration, and microfluidic type, controlling the fluid diffusion process and the spatial distribution of the refractive index, beam shaping is realized.

In this embodiment, in the step (3), the process of diffusion and convection can be effectively controlled by controlling the flow velocity and fluid type of the core fluid and the cladding fluid, thereby controlling the spatial distribution of fluid diffusion and refractive index; the details are as follows:

1) The refractive index distribution of different cross-sections of the fluid optical waveguide, assuming that the diffusion coefficient during the convection and diffusion process between the core fluid and the cladding fluid is constant (1×10 ^-9 m ² /s), and setting the control parameters of the peristaltic pump, Make the flow rate of the cladding and core fluids the same (both 2500pL/s), and make the diffusion effect along the fluid direction and the vertical fluid direction more obvious, and obtain the refraction at the cross section at different positions along the fluid flow direction As shown in Figure 3, the refractive index distribution curve tends to be flatter gradually as the refractive index distribution moves away from the fluid inlet. The most direct effect of this refractive index distribution is that the focal length of the vertically incident laser beam can be adjusted.

2) The influence of flow velocity on the distribution of the refractive index. In order to study the influence of the flow velocity of the fluid on the distribution of the refractive index, keeping other parameters unchanged, the refractive index distribution at the cross section at the center of the fluid flow direction (that is, where the laser beam is incident) is selected. As a reference, the influence of the fluid velocity on the distribution of the refractive index of the waveguide is obtained. As shown in Figure 4, when the flow velocity is low (Q ₁ =Q ₂ =Q _c =1000pL/s), the refractive index distribution is relatively flat, and when the flow velocity is high (Q ₁ =Q ₂ =Q _c =5000pL/s), the refractive index distribution is relatively sharp. This change can adjust the refractive index distribution by adjusting the flow velocity under the condition that the position of the beam remains unchanged, so as to realize the continuous adjustment of the beam convergence, that is, the continuous dynamic shaping of the beam.

3) The influence of different cladding flow rates on both sides on the refractive index distribution. The condition discussed above is the case where the flow rate of the core layer is the same as that of the cladding layers on both sides. The result of this flow rate condition is that the refractive index center is at the center of the fluid microcavity place. If the cladding fluid on one side is kept constant and the flow velocity of the cladding fluid on the other side is changed, the refractive index distribution of the fluid optical waveguide can be adjusted more flexibly, and an asymmetric refractive index distribution along the optical axis can be obtained, which in turn can control the beam's deflection. Also select the refractive index distribution at the cross section at the center position along the fluid flow direction (that is, where the laser beam is incident) as a reference, keep Q _c = Q ₂ = 2500pL/s, change Q ₁ , that is, the flow velocity of the cladding layer and the core layer on one side The constant is 2500pL/s, and the cladding flow rate on the other side is respectively selected as 500pL/s, 1500pL/s, 2500pL/s, 5000pL/s and 10000pL/s. At this time, the center of the refractive index distribution changes from -25μm to 28μm, as shown in the figure 5. The most direct impact of this spatial refractive index shift on the light is that it can realize the focus and deflection of the beam, and the deflection angle can be continuously adjusted with the change of the cladding flow velocity.

4) The influence of the refractive index of the cladding fluid being higher than that of the core fluid on the distribution of the refractive index of the fluid optical waveguide. When the cladding fluid adopts dilute ethylene glycol solution with a higher Ionized water while maintaining equal core and cladding fluid flow rates. When the fluid flow velocity is continuously adjusted, the refractive index distribution at the cross section at the center position along the fluid flow direction (that is, where the laser beam is incident) is obtained, as shown in Figure 6. It can be seen from Figure 6 that the refractive index distribution has a central depression. The simplest application of this distribution is on the beam splitting device of the beam, and the beam is focused while splitting the beam. In addition, dynamically adjusting the flow rate of the cladding fluid, for example, the lower left curve in Figure 6 shows the refractive index distribution when Q ₁ =10000pL/s, Q _c =Q ₂ =2500pL/s, which can realize continuous adjustment of the beam splitting ratio.

5) The influence of temperature, concentration, and type of microfluid on the distribution of the refractive index of the fluid optical waveguide. The influence of the temperature change on the distribution of the refractive index of the fluid optical waveguide is manifested in the increase in the temperature of the core and cladding fluids, which increases the diffusion coefficient (For example, when the core fluid uses ethylene glycol solution with a mass fraction of 0.8, when the temperature changes from 30°C to 50°C, the diffusion coefficient changes from 3.19×10 ^-10 m ² /s to 4.63×10 ^-10 m ² /s), thereby making the refractive index distribution curve of the fluid optical waveguide more gentle; the influence of the temperature change on the core fluid and the cladding fluid is consistent. The impact of the concentration change on the distribution of the refractive index of the fluid optical waveguide, the higher the concentration, the smaller the diffusion coefficient (for example, when the concentration ratio of ethylene glycol to deionized water is between 0.0250-0.950, the variation range of the diffusion coefficient is 9.28 ×10 ^-10 m ² /s to 1.67×10 ^-10 m ² /s), which in turn makes the refractive index distribution curve of the fluid optical waveguide sharper; the influence of the concentration change on the core fluid and cladding fluid Trends are consistent but can be individually regulated. The impact of the type of microfluid on the distribution of the refractive index of the fluid optical waveguide is manifested in that different microfluids have different viscosity coefficients, and the viscous resistance between the fluid microcavity wall and the fluid affects the diffusion process of the microfluid. At the position of the cavity wall, the fluid velocity is lower than that at the center of the microcavity, and the area where the flow velocity decreases diffuses more obviously. Therefore, compared with the refractive index distribution curve at the center, the refractive index distribution at the edge is relatively smooth.

Claims (3)

1. A light beam shaping device based on microfluidic optical technology, characterized in that: it includes a fluid optical waveguide main body, an incident laser, a beam receiving surface and an outflow fluid reservoir, and the fluid optical waveguide main body has a The flow channel comprises a core fluid inlet, two symmetrical cladding fluid inlets, a fluid microcavity and two symmetrical fluid outlets, the core fluid inlet and the cladding fluid inlet are all connected to the The inlet side of the fluid microcavity is connected, the outlet side of the fluid microcavity is connected with two fluid outlets, and the fluid outlets are connected with the outflow fluid reservoir, the incident laser and the beam receiving surface are arranged coaxially, the The axis of the incident laser and the beam receiving surface intersects the axis of the fluid flow direction, the incident laser and the beam receiving surface are symmetrically placed with the intersection point as the center of symmetry, and the incident laser injects the laser beam of the set wavelength into the In the fluid optical waveguide, the beam propagation direction is 90°±10° to the fluid flow direction, and the beam receiving surface receives the output beam after passing through the fluid optical waveguide. 2 . The beam shaping device based on microfluidic optical technology according to claim 1 , wherein the beam propagation direction is perpendicular to the fluid flow direction, and the beam receiving surface is coaxial with the incident laser. 3 . 3. The beam shaping device based on microfluidic optical technology as claimed in claim 1 or 2, characterized in that: the beam shaping device also includes a peristaltic pump for injecting fluid, and the peristaltic pump for injecting fluid is located in the core fluid Inlet, cladding fluid inlet.

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