Ultra-narrowband te polarization spectrally selective absorber based on cascaded grating structure

Abstract

An ultra-narrow-band TE (transverse electric) polarizing spectrum selective absorber based on a cascaded fiber grating structure comprises a metal grating layer and a Bragg grating layer from top to bottom, wherein a metal film reflecting layer is further arranged under the Bragg grating layer; the period of the metal grating layer at the top is 365-375nm, the duty ratio of the metal grating layer at the top is 0.48-0.52, the thickness of the metal grating layer at the top is 45-55 nm, the Bragg grating layer in the middle is formed by less than five pairs of dielectric slabs with high refractive index and dielectric slabs with low refractive index, the dielectric slabs with the high refractive index and the dielectric slabs with the low refractive index are arranged in a staggered manner, the thickness of each dielectric slab with the high refractive index is 270-290 nm, the thickness of each dielectric slab with the low refractive index is 300-320 nm, and the thickness of the metal film reflecting film at the bottom is larger than the skin depth of light in the infrared band. The ultra-narrow-band TE polarizing spectrum selective absorber based on the cascaded fiber grating structure can be processed by an electron-beam direct writing device with a microelectronics technology, the materials are convenient to obtain, the manufacturing cost is low, mass production can be realized, and the absorber has broad practical prospect.

Description

technical field [0001] This patent relates to an ultra-narrowband spectrally selective absorber, especially an ultranarrowband TE polarization spectrally selective absorber based on a cascaded grating structure. Background technique [0002] Generally, absorbers are divided into two types: one is a broadband absorber, which has high absorption in a certain bandwidth range, and is mainly used in the field of thin-film solar cells; the other is a spectrally selective absorber, namely It has ideal absorption in a narrow bandwidth, and is mainly used to design high-sensitivity detectors, thermal imaging devices, and narrow-band absorption / thermal radiators. To achieve ideal spectrally selective absorption, many subwavelength structures have been proposed, such as metamaterials, metallic nanoparticles, and so on. Among the proposed structures, the one-dimensional metal grating structure can also be used to achieve enhanced absorption, and its structure is simple, and its design ...

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Problems solved by technology

However, these selective absorbers, whether based on complex metamaterial structures or simple metal grating structures, have common defects: poor spatial coherence, limited narrow-band spectrum (bandwidth is usually on the order of hundreds of nanometers, not narrow enough)

However, the TM polarized narrow-band absorber / heat radiator has a big defect. Its Bragg grating is usually composed of 20 pairs of high-refractive-index dielectric layers and low-refractive-index dielectric layers. Therefore, its fabrication is complicated and costly, which is not conducive to practical application.

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