Broadband directional light emission structure and design method

Abstract

The invention relates to a broadband directional light emission structure and a design method, the broadband directional light emission structure comprises a plurality of independent super-lens rings, and each super-lens ring is composed of a plurality of elements; the focuses of the super-lens rings are different, and the larger the radius of the super-lens rings is, the shorter the focal length of the focuses is. According to the invention, heat radiation can be effectively and directionally radiated.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano photonics, and in particular to a broadband directional light emission structure and a design method thereof. Background Art

[0002] With the continuous advancement of semiconductor technology, its integration level continues to increase, and high-performance core particles have emerged. At the same time, its heat generation continues to increase. If the heat cannot be dissipated in time, the temperature inside the core particle will be too high, which will seriously affect the working performance and life of the core particle. In the prior art, through silicon vias (TSV) or microfluidics are used to remove the heat generated by the core particles through heat conduction and heat convection. However, for high-power core particles such as automotive-grade, the heat generated by thermal radiation at the extreme hot spots (hot spots) during operation cannot be ignored, and the prior art often makes it difficult to achieve radiation cooling of the core particles. Therefore, in order to avoid overheating of the local junction temperature of the core particle, it is a very effective way to establish an additional radiation heat dissipation channel without affecting the existing heat dissipation conditions.

[0003] Due to the thinness of the die in the core particle and the high power consumption accumulation, the core particle in the working state will have an extreme hot spot at a node of the die. The hot spot generates incoherent, non-polarized long-wave infrared electromagnetic waves in any direction through thermal radiation, and its light source can be regarded as a three-dimensional ellipsoid. The light source is split into countless small ellipsoidal light sources, and each small ellipsoidal light source can be regarded as a large focal depth focus formed by parallel light focusing through a lens. Then, according to the principle of reversible optical path, when a large focal depth lens is placed on the upper surface of the die, the ellipsoidal light source inside it will be converted into parallel light through the lens and emitted into the upper thermal interface material (TIM), and then it will be formed into a periodic array to achieve directional cooling of thermal radiation. In addition, the lens needs to fit tightly on the die inside the core particle, which requires the focal length of the lens to be extremely short. However, the traditional optical lens is too large to be integrated and packaged in the core particle, and due to the limitations of optical theory, it is difficult to achieve short focal length and large focal depth at the same time. Micro-nano optical metasurface is a two-dimensional planar optical element. Based on the theory of diffraction optics and the principle of phase modulation, it can freely manipulate the wavefront and has the advantages of small size and high integration. The current superlens technology can achieve a large depth of focus, but most superlens designs are optimized for a single wavelength, the working bandwidth is too narrow, and there are challenges in short focus. Therefore, there is currently no suitable micro-nano optical device that can be used for directional radiation heat dissipation of core particles. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a broadband directional light emitting structure and a design method, which can effectively dissipate heat from thermal radiation in a directional manner.

[0005] The technical solution adopted by the present invention to solve its technical problem is: to provide a broadband directional light emission structure, including a plurality of independent super lens rings, wherein each super lens ring is composed of a plurality of primitives; the focus of each super lens ring is different, and the larger the radius of the super lens ring, the shorter the focal length of the focus.

[0006] The phase of the element of the superlens ring is: in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

[0007] The basic unit is a metasurface micro-nano structure of a truncated cone structure.

[0008] The height and period of the primitives are equal.

[0009] The technical solution adopted by the present invention to solve the technical problem is: to provide a design method of a broadband directional light emitting structure, comprising the following steps:

[0010] Construct a primitive library, determine the height and period of each primitive in the primitive library, change the parameters of the primitive by simulation software, and obtain the phase and transmittance of each primitive in the primitive library at the working wavelength;

[0011] Assigning a focal length to each metalens ring according to the shape of the broadband directional light emission structure, and determining the required phase of the primitives of each metalens ring according to the number and focal length of the primitives of each metalens ring;

[0012] A primitive that meets the required phase and has a transmittance exceeding a threshold is found from a primitive library and filled into the super lens ring to obtain the broadband directional light emission structure.

[0013] The required phase of the element of the metalens ring is: in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

[0014] The basic unit is a metasurface micro-nano structure of a truncated cone structure.

[0015] The parameters of the primitive are the upper base radius and the lower base radius of the truncated cone structure.

[0016] The height and period of the primitives are equal.

[0017] Beneficial Effects

[0018] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention can effectively shorten the focal length of the metalens without affecting other indicators, thereby achieving a short focal length and a large focal depth, thereby adding an additional radiation cooling channel for core heat dissipation, solving the problem of difficulty in cooling extreme hot spots when the core works at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of a broadband directional light emission structure according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of the structure of a primitive in an embodiment of the present invention;

[0021] Figure 3 is a phase diagram of a primitive library in an embodiment of the present invention;

[0022] Figure 4 is a transmittance map of a primitive library in an embodiment of the present invention;

[0023] Figure 5 is the phase distribution diagram required for the broadband directional light emitting structure according to the embodiment of the present invention;

[0024] Figure 6 is a schematic diagram of a broadband directional light emission structure in an embodiment of the present invention;

[0025] Figure 7 is a simulation result diagram of a broadband directional light emission structure in an embodiment of the present invention;

[0026] Figure 8 is an application schematic diagram of a broadband directional light emitting structure according to an embodiment of the present invention;

[0027] Fig. 9 It is a schematic diagram of the thermal radiation directional scheme of the broadband directional light emitting structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0029] An embodiment of the present invention relates to a broadband directional light emission structure, comprising a plurality of independent superlens rings, wherein each superlens ring is composed of a plurality of primitives; the focus of each superlens ring is different, and the larger the radius of the superlens ring, the shorter the focal length of the focus.

[0030] In order to achieve the effect of short focal length and large focal depth, this embodiment adopts the ring allocation method to design a broadband directional light emission structure. The ring allocation method refers to dividing the metalens structure from the inside to the outside into multiple independent metalens rings, and according to the phase control principle of electromagnetic waves, calculating the phase information corresponding to each element position in each metalens ring, thereby obtaining its geometric information. Figure 1 As shown, each metalens ring generates a focus independently, and as the radius of the metalens ring increases, the focal length of the focus gradually shortens, and the distance between each focus can be determined by the diffraction limit and the Rayleigh criterion. Finally, the focuses generated by different metalens rings are connected together to form a focus effect with a short focal length and a large focal depth. The complete metalens composed of multiple metalens rings is the broadband directional light emission structure of this embodiment.

[0031] In this embodiment, the phase transmission principle of the metalens is used for design, and each element in the metalens ring is independently designed so that the electromagnetic waves released by the heat source can be emitted in parallel after passing through different metalens rings. In order to achieve the focusing function, the phase at a given position (x, y) on a metalens ring can be expressed as:

[0032]

[0033] in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

[0034] The primitive in this embodiment may adopt a metasurface micro-nanostructure of a truncated cone structure, and the height and period of the truncated cone structure are the same.

[0035] The design process is explained below using the long-wave infrared broadband directional light emission structure as an example.

[0036] Firstly, a primitive library is constructed, and the height and period of each primitive in the primitive library are determined. The parameters of the primitive are changed through simulation software to obtain the phase and transmittance of each primitive in the primitive library at the working wavelength.

[0037] In order to achieve the radiative cooling effect, this embodiment needs to select a polarization-insensitive metasurface micro-nanostructure as the primitive, and it needs to have a high external quantum efficiency to achieve high efficiency of radiative heat dissipation. After comparing multiple primitive shapes, this embodiment finally selects a truncated cone metasurface micro-nanostructure (see Figure 2 ) as primitives.

[0038] When establishing the primitive library, the height H is set to 6 μm, the period P is set to 6 μm, and the upper base radius r1 and the lower base radius r2 of the truncated cone structure are used as variables. The parameters are scanned by simulation software. When the working wavelength is 8 μm, the phase of each primitive in the primitive library is obtained (see Figure 3) and transmittance (see Figure 4 ).

[0039] Then, the focal length of each metalens ring is assigned according to the shape of the broadband directional light emitting structure. The focal length can be determined by the diffraction limit and the Rayleigh criterion. Then, the required phase of the element of each metalens ring is determined according to the number of elements and the focal length of each metalens ring.

[0040] After obtaining the primitive parameter data, different focal lengths are assigned to the metalens rings in turn according to the shape of the long-wave infrared broadband directional light emission structure. In this embodiment, the length and width of the long-wave infrared broadband directional light emission structure are both 102 μm, and it can be divided into 5 metalens rings. According to the number of primitives and the focal length, the relationship between the required phase and coordinates of each metalens ring in the long-wave infrared broadband directional light emission structure is obtained (see Figure 5 ).

[0041] Among them, the required phase of the primitive element of each metalens ring in the long-wave infrared broadband directional light emission structure is:

[0042]

[0043] in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

[0044] Finally, a primitive that meets the required phase and has a transmittance exceeding a threshold is found from the primitive library and filled into the superlens ring to obtain the broadband directional light emission structure.

[0045] In this embodiment, based on the established primitive library, primitives that meet the phase requirements and have a transmittance greater than 0.6 are screened, and the found primitives are filled into the metalens ring to obtain a long-wave infrared broadband directional light emission structure (see Figure 6 ). Through simulation software, the boundary is set as periodic boundary condition, and finally the simulation result of the long-wave infrared broadband directional light emission structure at 6-15μm is obtained (see Figure 7 ), which achieves the effect of short focal length and large focal depth within a wide bandwidth.

[0046] In this embodiment, the designed long-wave infrared broadband directional light emitting structure is periodically arranged in the x and y directions to obtain a long-wave infrared broadband directional light emitting structure array. The general operating temperature of the high-power core particle is about 360K, and the maximum operating temperature is about 400K. According to Planck's blackbody radiation law, the core particle will generate non-polarized, incoherent, arbitrary-direction broadband electromagnetic waves with a wavelength of 7-14μm when working. Figure 8As shown, the long-wave infrared broadband directional light emission structure array of this embodiment is placed on the upper surface of the core particle, and the device is connected to the upper packaging layer through a thermal interface material (TIM). According to the principle of reversible light path, the thermal radiation point source generated inside the core particle will be extracted as parallel light after passing through the metasurface array and emitted to the thermal interface material (TIM), thus realizing directional radiation cooling of the core particle (see Fig. 9 ).

[0047] It is not difficult to find that the present invention can effectively shorten the focal length of the metalens without affecting other indicators, achieving a short focal length and a large focal depth, thereby adding an additional radiation cooling channel for core heat dissipation, solving the problem of difficulty in cooling extreme hot spots when the core works at high temperatures.

Claims

1. A broadband directional light emitting structure, characterized in that: The invention comprises a plurality of independent metalens rings, wherein each metalens ring is composed of a plurality of primitives; the focus of each metalens ring is different, and the larger the radius of the metalens ring is, the shorter the focal length of the focus is.

2. The broadband directional light emitting structure according to claim 1, characterized in that: The phase of the element of the superlens ring is: in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

3. The broadband directional light emitting structure according to claim 1, characterized in that: The basic unit is a metasurface micro-nano structure of a truncated cone structure.

4. The broadband directional light emitting structure according to claim 1, characterized in that: The height and period of the primitives are equal.

5. A method for designing a broadband directional light emitting structure, characterized in that: The following steps are involved: Build a primitive library, determine the height and period of each primitive in the primitive library, and change the parameters of the primitive through simulation software. Obtain the phase and transmittance of each primitive in the primitive library at the working wavelength; Assigning a focal length to each metalens ring according to the shape of the broadband directional light emission structure, and determining the required phase of the primitives of each metalens ring according to the number and focal length of the primitives of each metalens ring; A primitive that meets the required phase and has a transmittance exceeding a threshold is found from a primitive library and filled into the super lens ring to obtain the broadband directional light emission structure.

6. The design method of a broadband directional light emitting structure according to claim 5, characterized in that: The required phase of the element of the metalens ring is: in, is the phase of the primitive at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the metalens ring.

7. The method for designing a broadband directional light emitting structure according to claim 5, characterized in that: The basic unit is a metasurface micro-nano structure of a truncated cone structure.

8. The method for designing a broadband directional light emitting structure according to claim 6, characterized in that: The parameters of the primitive are the upper base radius and the lower base radius of the truncated cone structure.

9. The method for designing a broadband directional light emitting structure according to claim 5, characterized in that: The height and period of the primitives are equal.

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