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A three-layer all-dielectric rectangular grating that achieves -2-level broadband high efficiency

A rectangular grating, all-dielectric technology, applied in the field of three-layer all-dielectric rectangular grating, achieves the effect of small aspect ratio, simple structure, and high-efficiency negative second-order diffraction

Active Publication Date: 2021-09-07
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

No one has yet designed a high-efficiency diffraction grating for a transmissive multilayer dielectric rectangular grating

Method used

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  • A three-layer all-dielectric rectangular grating that achieves -2-level broadband high efficiency
  • A three-layer all-dielectric rectangular grating that achieves -2-level broadband high efficiency
  • A three-layer all-dielectric rectangular grating that achieves -2-level broadband high efficiency

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specific Embodiment approach 1

[0034] see first figure 1 , figure 1 It is a schematic diagram of a negative secondary high-efficiency three-layer all-dielectric rectangular grating in the 1.5 micron band of the present invention, in the figure: θ in represents the angle of incidence, θ -2 , θ 0 are the diffraction angles of -2 order and 0 order respectively, h 1 、h 2 and h 3 are the layer thicknesses of aluminum oxide, titanium dioxide and silicon dioxide in the three-layer all-dielectric rectangular grating structure, respectively. b represents the width of the grating ridge, and d represents the grating period (the duty cycle is f=b / d). Areas 1, 2, 3, 4, and 7 are homogeneous media. The grating vector K is located in the incident plane, the vibration direction of the TE polarized light corresponding to the electric field vector is perpendicular to the incident plane, and the TE polarized light is at a certain angle θ in =arcsin(λ / n 1 d) (defined as the quadratic Bragg angle) incident on the grati...

specific Embodiment approach 2

[0038] Due to different wavelengths, the corresponding refractive index of the material is also different. The three-layer structure is re-optimized below, and the grating structure is still used figure 1 Structure, re-optimize the structural parameters, when the grating duty cycle is 0.4263, the period is 0.8647 microns, and the depth h 1 184.2 nm, h 2 506 nm, h 3 When it is 186.1 nanometers, the effect is the best. Figure 9 , Figure 10 , Figure 11 , Figure 12 and Figure 13 , are the control variables for the duty cycle, duty cycle f, h1, h2, and h3 respectively, and study the influence of its tolerance on the -2nd order diffraction efficiency value. It can be seen that for each parameter variable, the diffraction efficiency output of more than 95% can be achieved within a large tolerance range. For the diffraction efficiency above 95% is the standard, the tolerance intervals are, period (833.9-924.2 nanometers), duty cycle (0.4076-0.4494), h1 (113.9-257.9 nanomet...

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Abstract

A three-layer all-dielectric rectangular grating that achieves ‑2-level broadband high efficiency, including fused silica as the medium in the incident area and the grating ridge is a three-layer all-dielectric rectangular grating, respectively, the first layer of aluminum oxide, the second layer of titanium dioxide, and the second layer of titanium dioxide The three-layer fused silica is characterized in that the three-layer rectangular grating has the largest refractive index in the middle layer, and the refractive index of each layer of material is between the refractive index of two adjacent materials. Bragg angle θ in =arcsin(λ / n 1 d) incident, n 1 is the refractive index of the incident area, d represents the grating period, and b represents the width of the grating ridge. The present invention can realize transmission-second-order diffraction efficiency close to 1 for TE polarized light. The grating has the characteristics of simple structure, rectangular structure, small aspect ratio, easy processing, and large manufacturing tolerance. It is easy to realize under the microelectronic deep etching process combined with today's optical holographic recording technology or electron beam direct writing technology, and the process is mature. , low cost, capable of mass production, and has important application prospects.

Description

technical field [0001] The invention relates to a broadband high-efficiency grating, in particular to a three-layer all-dielectric rectangular grating realizing -2-level broadband high efficiency. Background technique [0002] In the field of femtosecond lasers, spectroscopic devices such as prisms cannot be used due to the introduction of material dispersion. The grating can not only separate the spectrum, but also compensate the dispersion. It has the advantages of compensating dispersion, compact structure, high efficiency, and easy fabrication. It is the most important optical device in the femtosecond laser field. The all-dielectric rectangular grating has a higher damage threshold than the gold-plated grating, so the all-dielectric grating has important practical prospects. [0003] The all-dielectric rectangular grating is easy to manufacture, and can be processed by one-time exposure, development, etching and other conventional processes in the holographic interfere...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G02B5/18
CPCG02B5/1809
Inventor 周常河尹正坤余俊杰鲁云开
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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