A broadband directional light emitting structure and design method

Abstract

The present application relates to a kind of broadband directional light emitting structure and design method, wherein, broadband directional light emitting structure includes several independent superlens ring, wherein, each superlens ring is by multiple base element;The focal point of each superlens ring is different, and the greater the radius of the superlens ring, the shorter the focal length of focal point is.The present application can effectively direct heat dissipation to thermal radiation.

Description

Technical Field

[0001] This invention relates to the field of micro-nano photonics technology, and in particular to a broadband directional light emission structure and its design method. Background Technology

[0002] With the continuous advancement of semiconductor technology, its integration density is constantly increasing, leading to the emergence of high-performance chips. Simultaneously, the heat generated by these chips is also increasing. If heat dissipation is not timely, the internal temperature of the chip will become excessively high, severely impacting its performance and lifespan. Current technologies employ through-silicon vias (TSVs) or microfluidics to remove heat generated by the chip through heat conduction and convection. However, for high-power chips such as those used in automotive applications, the heat generated by thermal radiation from extreme hot spots during operation is also significant, and current technologies often struggle to achieve radiative cooling. Therefore, to prevent localized overheating of the chip junction, establishing an additional radiative heat dissipation channel without compromising existing heat dissipation conditions is a highly effective approach.

[0003] Due to the thinness of the die and the high power consumption of the die, an extreme hot spot will appear at a certain node of the die during operation. This hot spot generates incoherent, unpolarized, long-wave infrared electromagnetic waves in any direction through thermal radiation. The light source can be regarded as a three-dimensional ellipsoid. This light source is split into countless small ellipsoidal light sources, each of which can be regarded as a large depth of focus formed by parallel light being focused by a lens. Then, according to the principle of optical reversibility, when a large depth of focus lens is placed on the upper surface of the die, the ellipsoidal light source inside it will be transformed into parallel light through the lens and emitted into the upper thermal interface material (TIM). By arranging them into a periodic array, directional cooling of thermal radiation can be achieved. In addition, the lens needs to be tightly attached to the die inside the die, which requires an extremely short focal length. However, traditional optical lenses are too large to be integrated and packaged in the die, and due to the limitations of optical theory, it is difficult to achieve both short focal length and large depth of focus at the same time. Micro-nano optical metasurfaces are two-dimensional planar optical elements based on diffraction optics theory and phase modulation principles. They can freely manipulate wavefronts and possess advantages such as small size and high integration. Current superlens technology can achieve large depths of focal length, but most superlens designs are optimized for only a single wavelength, resulting in excessively narrow operating bandwidths and challenges in short focal lengths. Therefore, there is currently no suitable micro-nano optical device that can be applied to directional radiative heat dissipation of the core particle. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a broadband directional light emission structure and design method that can effectively dissipate heat 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 number of independent superlens rings, wherein each superlens ring is composed of multiple primitives; each superlens ring has a different focal point, and the larger the radius of the superlens ring, the shorter the focal length of the focal point.

[0006] The phase of the basic elements of the superlens ring is: in, Let λ be the phase of the primitive at coordinate position (x,y), λ be the working wavelength, and F be the focal length of the superlens ring.

[0007] The basic unit is a metasurface micro / nano structure with a frustum structure.

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

[0009] The technical solution adopted by this invention to solve its technical problem is: to provide a design method for a broadband directional light emission structure, comprising the following steps:

[0010] Construct a primitive library and determine the height and period of each primitive in the primitive library. Change the parameters of the primitives using simulation software to obtain the phase and transmittance of each primitive in the primitive library at the working wavelength.

[0011] The focal length of each superlens ring is assigned according to the shape of the broadband directional light emission structure, and the required phase of each superlens ring is determined according to the number of primitives and the focal length of each superlens ring.

[0012] Find the primitives that meet the required phase and have a transmittance exceeding the threshold from the primitive library and fill them into the superlens ring to obtain the broadband directional light emission structure.

[0013] The required phase of the primitives of the superlens ring is: in, Let λ be the phase of the primitive at coordinate position (x,y), λ be the working wavelength, and F be the focal length of the superlens ring.

[0014] The basic unit is a metasurface micro / nano structure with a frustum structure.

[0015] The parameters of the basic element are the upper and lower base radii of the frustum 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 superlens without affecting other indicators, achieving a short focal length and a large focal depth, thereby adding an additional radiation cooling channel for heat dissipation of the core particle, and solving the problem of difficult cooling of extreme hot spots under high temperature operation of the core particle. Attached Figure Description

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

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

[0021] Figure 3 This is the phase diagram of the primitive library in the embodiments of the present invention;

[0022] Figure 4 This is a transmittance diagram of the element library in an embodiment of the present invention;

[0023] Figure 5 This is the phase distribution diagram required for the broadband directional light emission structure in the embodiment of the present invention;

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

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

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

[0027] Figure 9 This is a schematic diagram of the thermal radiation orientation scheme of the broadband directional light emission structure according to an embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0029] The embodiments of the present invention relate to a broadband directional light emission structure, including a plurality of independent superlens rings, wherein each superlens ring is composed of multiple primitives; each superlens ring has a different focal point, and the larger the radius of the superlens ring, the shorter the focal length of the focal point.

[0030] To achieve a short focal length and large depth of focus, this embodiment employs a ring-based allocation method for designing the broadband directional light emission structure. The ring-based allocation method involves dividing the superlens structure into multiple independent superlens rings from the inside out, and calculating the phase information corresponding to each element position within each superlens ring based on the phase modulation principle of electromagnetic waves, thereby deriving its geometric information. For example... Figure 1 As shown, each superlens ring independently generates a focal point, and as the radius of the superlens ring increases, the focal length of the focal point gradually decreases. The distance between each focal point can be determined by the diffraction limit and the Rayleigh criterion. Ultimately, the focal points generated by different superlens rings merge into one, forming a focal effect with a short focal length and a large depth of field. The complete superlens composed of multiple superlens rings constitutes the broadband directional light emission structure of this embodiment.

[0031] This embodiment utilizes the phase transmission principle of a superlens for design, independently designing each element in the superlens ring so that the electromagnetic waves emitted by the heat source can exit in parallel after passing through different superlens rings. To achieve the focusing function, the phase at a given position (x, y) on a certain superlens ring can be expressed as:

[0032]

[0033] in, Let λ be the phase of the primitive at coordinate position (x,y), λ be the working wavelength, and F be the focal length of the superlens ring.

[0034] The basic unit in this embodiment can be a metasurface micro / nano structure with a frustum structure, the height and period of which are the same.

[0035] The design process is illustrated below using a long-wave infrared broadband directional light emitting structure as an example.

[0036] First, a primitive library is constructed, and the height and period of each primitive in the primitive library are determined. By changing the parameters of the primitives through simulation software, the phase and transmittance of each primitive in the primitive library at the working wavelength are obtained.

[0037] To achieve radiative cooling, this embodiment requires selecting a polarization-insensitive metasurface micro / nanostructure as the basic unit, which also needs to possess a high external quantum efficiency to achieve efficient radiative heat dissipation. After comparing several basic unit shapes, this embodiment ultimately selected a frustum-shaped metasurface micro / nanostructure (see...). Figure 2 ) as a basic unit.

[0038] When establishing the primitive library, the height H was set to 6 μm and the period P to 6 μm. The upper base radius r1 and lower base radius r2 of the frustum structure were used as variables. Parameter scanning was performed using simulation software. When the working wavelength was 8 μm, the phase of each primitive in the primitive library was obtained (see...). Figure 3) and transmittance (see Figure 4 ).

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

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

[0041] The required phase for each element of the superlens ring in the long-wave infrared broadband directional light emission structure is:

[0042]

[0043] in, Let λ be the phase of the primitive at coordinate position (x,y), λ be the working wavelength, and F be the focal length of the superlens ring.

[0044] Finally, primitives that meet the required phase and have a transmittance exceeding the threshold are selected 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 selected. The selected primitives are then filled into the superlens ring to obtain a long-wave infrared broadband directional light emission structure (see...). Figure 6 Simulations were performed using simulation software, with periodic boundary conditions set. The simulation results for this long-wave infrared broadband directional light-emitting structure in the 6-15 μm range were finally obtained (see [link to simulation results]). Figure 7 It achieves the effect of short focal length and large focal depth within a wide bandwidth range.

[0046] This embodiment arranges the designed long-wave infrared broadband directional light emitting structure periodically in the x and y directions to obtain a long-wave infrared broadband directional light emitting structure array. The typical operating temperature of the high-power core is approximately 360K, with a maximum operating temperature of approximately 400K. According to Planck's blackbody radiation law, the core will generate unpolarized, incoherent, broadband electromagnetic waves with wavelengths of 7-14μm in any direction during operation. Figure 8As shown, the long-wave infrared broadband directional light emitting structure array of this embodiment is placed on the upper surface of the core, and the device is connected to the upper encapsulation layer through a thermal interface material (TIM). According to the principle of optical path reversibility, the thermal radiation point source generated inside the core will be transformed into parallel light after passing through the metasurface array and extracted, and emitted onto the thermal interface material (TIM), realizing directional radiative cooling of the core (see...). Figure 9 ).

[0047] It is easy to see that the present invention can effectively shorten the focal length of the superlens without affecting other indicators, achieving a short focal length and a large focal depth, thereby adding an extra radiation cooling channel for heat dissipation of the core particle and solving the problem of difficult cooling of extreme hot spots under high temperature operation of the core particle.

Claims

1. A broadband directional light emitting structure, characterized by, The superlens ring comprises a plurality of independent superlens rings, each of which is composed of a plurality of units; the focal points of each superlens ring are different and are connected together; the greater the radius of the superlens ring is, the shorter the focal length of the focal point is.

2. The broadband directional light launch structure of Claim 1, wherein, The phase of the base element of the superlens ring is: wherein, is the phase of the base element at coordinate position (x, y), λ is the working wavelength, and F is the focal length of the superlens ring.

3. The broadband directional light launch structure of Claim 1, wherein, The unit is a frustum structure super-structured surface micro-nano structure.

4. The broadband directional light launch structure of Claim 1, wherein, The height and the period of the unit are equal.

5. A method of designing a broadband directional light emitting structure as claimed in any one of claims 1-4, characterized in that, The method comprises the following steps: constructing a unit library and determining the height and the period of each unit in the unit library, changing the parameters of the unit through simulation software, obtaining the phase and the transmittance of each unit in the unit library at the working wavelength, assigning the focal length to each superlens ring according to the shape of the broadband directional light emitting structure, and determining the required phase of the unit of each superlens ring according to the number of units and the focal length of each superlens ring, filling the unit meeting the required phase and the transmittance exceeding the threshold value from the unit library into the superlens ring to obtain the broadband directional light emitting structure.

6. The method of designing a broadband directional light emission structure according to claim 5, wherein, The required phase of the superlens ring's cells is: where, is the phase of a cell at coordinate position (x, y), λ is the operating wavelength, and F is the focal length of the superlens ring.

7. The method of designing a broadband directional light emission structure according to claim 5, wherein, The unit is a frustum structure super-structured surface micro-nano structure.

8. The method of designing a broadband directional light emitting structure according to claim 6, wherein, The parameters of the unit are the upper base radius and the lower base radius of the frustum structure.

9. The method of designing a broadband directional light emitting structure according to claim 5, wherein, The height and the period of the unit are equal.

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