Bandwidth convertible mid-infrared absorption of one-dimensional quasi-periodic system containing Dirac semimetals

The absorption properties of one-dimensional quasi-periodic (Fibonacci and Thue Morse sequences) systems composed of Dirac semimetal are investigated. Numerical results show that nearly perfect broadband or narrowband absorption in mid-infrared range can be obtained using the same constituents with different sequences. For the Fibonacci sequence, a 90% absorption band with a relative bandwidth over 38% can be obtained, which results from the superimposing multiple resonances, and the average absorption over the absorption band can reach 97.2%. A nearly perfect narrowband absorption can be realized by the Thue Morse sequence due to the strong field localization effect. The absorption can be tunable by changing the Fermi energy of the Dirac semimetal, the geometry parameters and the permittivity of the constituents. In addition, the effects of the polarization and the incident angles of the incident wave on the absorption performance are also calculated. Our demonstrated structures have promising absorption properties and the results are valuable in designing tunable optoelectronic devices such as mid-infrared detectors and filters.