Tunable high-quality-factor absorption in a graphene monolayer based on quasi-bound states in the continuum

Jun Wu; Yasong Sun; Feng Wu; Biyuan Wu; Xiaohu Wu

doi:10.3762/bjnano.13.59

Tunable high-quality-factor absorption in a graphene monolayer based on quasi-bound states in the continuum

Beilstein J Nanotechnol. 2022 Jul 19:13:675-681. doi: 10.3762/bjnano.13.59. eCollection 2022.

Authors

Jun Wu¹, Yasong Sun^{2

3}, Feng Wu⁴, Biyuan Wu^{2

5}, Xiaohu Wu⁵

Affiliations

¹ College of Electrical Engineering, Anhui Polytechnic University, Wuhu, 241000, China.
² Basic Research Center, School of Power and Energy, Northwestern Polytechnical University, Xi'an 710064, Shaanxi, China.
³ Center of Computational Physics and Energy Science, Yangtze River Delta Research Institute of NPU, Northwestern Polytechnical University, Taicang 215400, Jiangsu, China.
⁴ School of Optoelectronic Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China.
⁵ Shandong Institute of Advanced Technology, Jinan 250100, China.

Abstract

A tunable graphene absorber, composed of a graphene monolayer and a substrate spaced by a subwavelength dielectric grating, is proposed and investigated. Strong light absorption in the graphene monolayer is achieved due to the formation of embedded optical quasi-bound states in the continuum in the subwavelength dielectric grating. The physical origin of the absorption with high quality factor is examined by investigating the electromagnetic field distributions. Interestingly, we found that the proposed absorber possesses high spatial directivity and performs similar to an antenna, which can also be utilized as a thermal emitter. Besides, the spectral position of the absorption peak can not only be adjusted by changing the geometrical parameters of dielectric grating, but it is also tunable by a small change in the Fermi level of the graphene sheet. This novel scheme to tune the absorption of graphene may find potential applications for the realization of ultrasensitive biosensors, photodetectors, and narrow-band filters.

Keywords: bound states in the continuum; graphene; gratings; selective absorption.

Grants and funding

The authors acknowledge the support of the National Natural Science Foundation of China (Grant Nos. 61405217, 52106099 and 12104105), the Zhejiang Provincial Natural Science Foundation (Grant No. LY20F050001), the Anhui Provincial Natural Science Foundation (Grant No. 2108085MF231), the Anhui Polytechnic University Research Startup Foundation (Grant No. 2020YQQ042), the Pre-research Project of National Natural Science Foundation of Anhui Polytechnic University (Grant No. Xjky02202003), the Natural Science Foundation of Shandong Province (Grant No. ZR2020LLZ004), and the Start-Up Funding of Guangdong Polytechnic Normal University (Grant No. 2021SDKYA033).