A highly variable confocal, homogenizing micro-optical device

Abstract

A kind of highly variable confocal, homogenization micro-optical device.The optical device is composed of variable height axisymmetric linear period micro straight prism structure, the working distance of central micro straight prism is defined as the working distance of device, after solving the relationship between the working distance of linear period micro straight prism structure and its height, the height change general formula is established, by changing the height of linear period micro straight prism structure, after the incident light is perpendicular to the bottom surface of device and passes through the device, confocal effect can be achieved, and energy is obviously concentrated, the maximum intensity is doubled with the expansion of structure.This application has important application value and application prospect in the field of focusing micro-nano optical device design, beam shaping and high aspect ratio micro groove measurement technology.And the X wave generated has good application prospect in the field of optical information processing and transmission and touch screen detection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of micro-optical device design, relates to local field enhancement, Bessel beam shaping and X-beam application, and particularly relates to a highly variable confocal and homogenized micro-optical device capable of effectively enhancing local field and having strong focusing ability. BACKGROUND

[0002] The generation of local field enhancement can enhance the linear or nonlinear response of the medium, and has wide application in many fields such as photonics, nanosensing, near-field optical microscopy, biological detection and nanomedicine, and has important practical significance. However, at present, most of the local field enhancement is based on metal nanostructures, and the complexity of the material is also increased accordingly while achieving the effect of local field enhancement, which is very unfavorable for application.

[0003] In the field of Bessel beam shaping, focusing will affect the light intensity around the focal plane of the Bessel function distribution, and will decrease with the decrease of the numerical aperture value of the optical device. The use of axicon-shaped Bessel beams can improve the above problems. The previous micro-optical device composed of micro-straight triangular prisms with the same height, when the light is vertically incident on the device and passes through, the refractive surface of the two symmetrical triangular prisms has the same inclination, and as the linear expansion of the structure, the working distance of the device is larger, the refractive light of the symmetrical micro-straight triangular prisms with the same k value converges, thereby a continuous focal spot is generated in the working distance, achieving the effect of homogenization, but there is no obvious beneficial effect on the light intensity. SUMMARY

[0004] The purpose of the present application is to break through the technical limitations in the fields of local field enhancement and Bessel beam shaping, and to provide a highly variable confocal and homogenized micro-optical device capable of effectively improving the focusing ability and the field energy.

[0005] The highly variable confocal and homogenized micro-optical device of the present application can improve the focusing ability and the field intensity, and X-beams are generated in the results, which not only provides a new way in the fields of local field enhancement and Bessel beam shaping, but also has application potential in the fields of high aspect ratio structure micro-slot measurement, optical information processing and transmission, and touch screen detection.

[0006] The highly variable confocal and homogenized micro-optical device, characterized in that the maximum working distance Z of the device max is determined by the following formula:

[0007] Z max =Λ·tan β1

[0008] wherein, n sin α1 = n'sin g1, n is the refractive index of the micro straight prism, n' is the air refractive index.

[0009] The height-variable confocal and homogenized micro-optical device is characterized in that the micro straight prism material is optical glass.

[0010] The height-variable confocal and homogenized micro-optical device is characterized in that in the device, the height h1 of the central micro straight prism is determined by Snell's law and a formula of design principle of the diffractive element.

[0011] The height-variable confocal and homogenized micro-optical device is characterized in that when the micro-optical device is of equal height, i.e. h k = h1, a continuous focal spot appears in the working distance, and with the increase of the number of micro straight prisms in the device, the continuity of the focal spot is enhanced.

[0012] The height-variable confocal and homogenized micro-optical device is characterized in that when the micro-optical device is of unequal height, the continuous focal spot appearing in the working distance at equal height converges, the confocal effect can be achieved, and the energy is obviously concentrated.

[0013] The height-variable confocal and homogenized micro-optical device is characterized in that the height variation of the linear periodic micro straight prism structure in the micro-optical device is as follows:

[0014]

[0015] The height-variable confocal and homogenized micro-optical device is characterized in that the design method establishes a design formula of the micro-optical element, changes the structure height in the device, and the high device converges the linear discrete focal points generated by the previous equal height structure, the working distance of each structure is all cut off in the working distance of the central micro straight prism, and the light convergence and the overall working distance of the device can be controlled.

[0016] Compared with the prior art, the beneficial effects of the present application include:

[0017] (1) The present application establishes a new design theory formula of micro-optical device, and has a complete theoretical system.

[0018] (2) The present application establishes a design formula of the micro-optical element, changes the structure height in the device, and the high device converges the linear discrete focal points generated by the previous equal height structure, the working distance of each structure is all cut off in the working distance of the central micro straight prism, and the light convergence and the overall working distance of the device can be controlled.

[0019] ​(3) The device appearance rule of the application is simple in shape, easy to process, and can reduce processing cost and difficulty, and the innovation and novelty are expected to be applied and innovated in the field of micro-nano optical structure and super surface device.

[0020] (4) The highly variable confocal and uniform light micro-optical device provided by the application can realize focusing and greatly enhance the energy of the field, and the structure size is in the micron level, and with the increase of the array k value, the focusing and field strength increasing capacity are doubled, which has important application prospect in the field of local field enhancement and Bessel beam shaping. The generated X-beam has application background in optical information processing and transmission and touch screen detection, and the isometric device has application potential in high aspect ratio structure micro slot measurement field. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a three-view of a k=1 height of 1 micron micro straight three-prism structure according to an embodiment of the application. Wherein: (a) is the main cross-sectional view of the k=1 height of 1 micron micro straight three-prism; (b) is the left cross-sectional view of the k=1 height of 1 micron micro straight three-prism; (c) is the top view of the k=1 height of 1 micron micro straight three-prism.

[0022] Figure 2 Figure 2 is a schematic diagram of an isometric uniform light micro-optical device structure when k=2 according to the application. Wherein: (a) is the main cross-sectional view of the k=2 isometric device; (b) is the left cross-sectional view of the k=2 isometric device; (c) is the top view of the k=2 isometric device.

[0023] Figure 3 Figure 3 is a schematic diagram of an isometric uniform light micro-optical device structure when k=4 according to the application. Wherein: (a) is the main cross-sectional view of the k=4 isometric device; (b) is the left cross-sectional view of the k=4 isometric device; (c) is the top view of the k=4 isometric device.

[0024] Figure 4 Figure 4 is an energy diagram of the isometric micro-optical device structure calculated by the finite difference time domain method according to the embodiment of the application. Wherein: (a) is the energy diagram of the k=1 height of 1 micron micro straight three-prism; (b) is the energy diagram of the k=2 isometric device; (c) is the energy diagram of the k=4 isometric device.

[0025] Figure 5 Figure 5 is a method display of the formula according to the application.

[0026] Figure 6 Figure 6 is a schematic diagram of a height variable confocal micro-optical device structure when k=2 according to the application. Wherein: (a) is the main cross-sectional view of the k=2 height variable confocal micro-optical device; (b) is the left cross-sectional view of the k=2 height variable confocal micro-optical device; (c) is the top view of the k=2 height variable confocal micro-optical device.

[0027] Figure 7 This is a schematic diagram of the confocal micro-optical device with height variation when k=3 provided by the present invention. Wherein: (a) is a front sectional view of the confocal micro-optical device with height variation when k=3; (b) is a left sectional view of the confocal micro-optical device with height variation when k=3; (c) is a top view of the confocal micro-optical device with height variation when k=3.

[0028] Figure 8 These are energy diagrams of confocal, homogenized micro-optical devices with varying heights, calculated using the finite-time-difference method according to embodiments of the present invention. Specifically: (a) is the energy diagram of a confocal micro-optical device with a height variation of k=2; (b) is the energy diagram of a confocal micro-optical device with a height variation of k=3. Detailed Implementation

[0029] To better understand this invention, the following embodiments are used to describe the technical solution of this invention in detail. However, the scope of protection of this invention is not limited to the following embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention. The embodiments of this invention are further described below with reference to the accompanying drawings:

[0030] The axisymmetric linear periodic micro-straight triangular prism structure in this invention can be fabricated using photolithography and dry etching techniques. The specific steps are as follows:

[0031] (1) Micro-straight triangular prism structures were fabricated by exposing a photosensitive medium and developing it using laser direct writing or electron beam direct writing methods.

[0032] (2) The micro-straight triangular prism structure is transferred onto optical glass using reactive ion etching or inductively coupled plasma etching techniques.

[0033] According to geometric optics theory, such as Figure 1 As shown, when parallel light is incident perpendicularly to the base of a right triangular prism along the Z direction, its maximum working distance Z is... max Determined by the following formula:

[0034] Z max =Λ·tan β1

[0035] in, n sin α1=n′sin γ1, where n is the refractive index of the micro-rectangular prism and n′ is the refractive index of air.

[0036] Specific application example 1

[0037] Examples of height-varying confocal, homogenizing micro-optical devices constructed from equal-height axisymmetric linear periodic micro-straight triangular prism structures and variable-height axisymmetric linear periodic micro-straight triangular prism structures:

[0038] The specific parameters of the equal-height axisymmetric linear periodic micro straight-triangular prism structure are as follows:

[0039] The material of the equal-height axisymmetric linear periodic micro straight-triangular prism structure is silicon dioxide (refractive index is 1.5), the design period is Λ=5 μm, and the design wavelength is 500 nm, According to optical theory, the length of the bottom of the central micro straight-triangular prism is 2Λ=10 μm, and the maximum working distance Z max =49.2 μm.

[0040] The specific parameters of the variable-height axisymmetric linear periodic micro straight-triangular prism structure are as follows:

[0041] The material of the variable-height axisymmetric linear periodic micro straight-triangular prism structure is silicon dioxide (refractive index is 1.5), the design period is Λ=5 μm, and the design wavelength is 500 nm, According to optical theory, the length of the bottom of the central micro straight-triangular prism is 2Λ=10 μm, and the maximum working distance Z max =49.24 μm, when k=1, the array is composed of only the central micro straight-triangular prism; when k=2, according to the established general formula, the height h2 of the two side micro straight-triangular prisms is 1.91 μm; when k=3, according to the established general formula, the height h2 of the two side micro straight-triangular prisms is 1.91 μm, and the height h3 of the third micro straight-triangular prism is 2.68 μm.

[0042] The focusing effect and field strength of the equal-height axisymmetric linear periodic micro straight-triangular prism structure calculated by the finite difference time domain method are as shown in Figure 4 .

[0043] The focusing effect and field strength of the variable-height micro straight-triangular prism array calculated by the finite difference time domain method are as shown in Figure 8 .

Claims

1. A confocal and homogenized micro-optical device, by changing the height of an axisymmetric linear periodic micro straight triangular prism structure made of optical glass, a confocal effect is achieved, and the energy is significantly concentrated, the maximum intensity is doubled with the increase of k value. The optical device is made of optical glass and is composed of an axially symmetric linear periodic micro straight prism structure with variable height, the axially symmetric linear periodic micro straight prism structure is used for focusing the light incident perpendicularly to the bottom surface of each micro straight prism within a working distance, concentrating energy and improving maximum intensity; the device is an axially symmetric linear periodic micro straight prism structure with variable height, the central micro straight prism is an isosceles structure, the period is 2Λ, the two side micro straight prisms are placed in mirror symmetry, the periods are both Λ, and the heights are h k , k = 1, 2, 3,... Wherein, the k of the central micro straight triangular prism is 1, and h1 is calculated according to Snell's law and the design principle formula of the diffraction element: To fix, Lambda is the period, lambda is the incident wavelength, and n is the refractive index of the micro straight triangular prism. Λ and h k The size is in the order of microns; the height h k The minimum acute angle is α k The refraction angle of the light passing through the kth structure is γ k The angle between the outermost refracted light and the base of the three-prism is β k The maximum working distance of the device is Z max The working distance of the fixed central micro straight three-prism is determined by the following formula: Z max = A tan β1 wherein nsin a1= n'sin g1, n is the refractive index of the micro-prism, n' is the refractive index of air; When each structure is equal in height, i.e., h k When each structure is equal in height, i.e., h When each structure is equal in height, i.e., h When the incident light is perpendicular to the bottom surface of the device and passes through the device, the working distance of the micro straight prism structure with the same k value on both sides is controlled to be the same as that of the central micro straight prism, so that the focal points are converged at a point, the confocal effect is achieved, the energy is obviously concentrated, the confocal effect is better with the linear increase of the k value of the device structure, and the intensity is doubled. The height-varying confocal and uniform light micro-optical device has the following height-varying general formula: h k = A tan a k Z max = A tan β k γ k = arcsin(n sin α k ) This design method converges the linear discrete focal points generated by the previous equal-height structure by establishing a design formula of the micro-optical element, changing the structure height of the device, and cutting off the working distance of each structure in the working distance of the central micro straight prism, so that the convergence of light and the overall working distance of the device can be controlled.

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