An Amplitude Tunable Dual-Band Bandpass Filter With Perfect Absorption and Its Sensing Applications

• Published in: IEEE sensors journal Vol. 24; no. 4; pp. 4387 - 4399
• Main Authors: Zhu, Aijun, Li, Zongteng, Cheng, Lei, Hu, Cong, Mahapatra, Rabi N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15-02-2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Absorption; Amplitude modulation; Band-pass filters; Bandpass filters; Dual band; dual-band bandpass filter; Figure of merit; Frequencies; Graphene; Metals; Metamaterials; Modulators; perfect absorber; Phase transitions; Sensors; terahertz (THz) sensor
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2023.3346441

A design is presented here that integrates a five-layer structure, which can achieve multiple functions with tunable amplitudes with a dual-band bandpass filter and perfect absorber for sensing applications. When used as a bandpass filter, the design has two center frequencies at 0.708 and 1.733 THz with a 3-dB bandwidth of 0.312 and 0.160 THz, respectively. Among them, the maximum transmission of the first frequency band can attain <inline-formula> <tex-math notation="LaTeX">\ge 90 </tex-math></inline-formula>%, while that of the second frequency band exceeds 70%. Using the phase transition characteristics of VO2 as the amplitude modulation principle, the amplitude modulation depth can reach 89.36% and 94.24%, respectively. As a sensor, a perfect absorption peak generated by this structure at 1.478 THz was used, with an absorption rate of up to 99%. Simulation results showed that its sensitivity, quality factor (<inline-formula> <tex-math notation="LaTeX">{Q}{)} </tex-math></inline-formula>, and figure of merit (FOM) could reach 0.247 THz/RIU, 21.497, and 3.592 RIU<inline-formula> <tex-math notation="LaTeX">^{-{1}} </tex-math></inline-formula>, respectively. The combination of multiple functions gives our design important application values for bandpass filters, modulators, sensors, and other fields.