Paper
20 January 2023 Fabrication of linear polarizer in 7-14um infrared region by metal-assisted chemical etching
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Abstract
With the widespread application of polarizers in infrared detection, military, medical and other fields, infrared polarizers have developed rapidly in the last decade, and it is becoming increasingly crucial to fabricate high-performance and low-cost polarizers. The paper presents a design for fabricating a linear polarizer operating in the 7-14 um by metal-assisted chemical etching. A subwavelength gold grating is fabricated on a silicon substrate by the lift-off process, then a subwavelength silicon grating structure is fabricated by the metal-assisted chemical etching process of silicon, an aluminum film is coated on the bottom of the groove and the ridge of the fabricated subwavelength silicon grating by electron beam evaporation coating. The structure is optimized by the rigorous coupled-wave analysis, we assess the effect of the grating parameters on the extinction ratio and transverse magnetic wave transmittance and optimize the parameters, and finally determined that the grating period is 400 nm, the duty cycle is 0.5, and the groove depth is 1200nm. The numerical simulation results demonstrate that the polarizer has the advantages of high extinction ratio and wide manufacturing tolerance in long wave infrared region (7-14um). Grating structures with high aspect ratio can be fabricated by metal-assisted chemical etching, which makes it possible to enhance the transmission of the silicon substrate. Therefore, anti-reflection structures can be designed to enhance the transmission of the silicon substrate in the long-wave infrared based on the effective medium theory.
© (2023) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fanfan Lu, Huaikun Wei, Angran Li, Tao Ren, Yilin Hong, and Keqiang Qiu "Fabrication of linear polarizer in 7-14um infrared region by metal-assisted chemical etching", Proc. SPIE 12555, AOPC 2022: Infrared Devices and Infrared Technology; and Terahertz Technology and Applications, 1255508 (20 January 2023); https://doi.org/10.1117/12.2648017
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KEYWORDS
Silicon

Polarizers

Infrared radiation

Wet etching

Aluminum

Linear polarizers

Refractive index

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