中国物理B ›› 2022, Vol. 31 ›› Issue (11): 114101-114101.doi: 10.1088/1674-1056/ac6015

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Ultra-wideband surface plasmonic bandpass filter with extremely wide upper-band rejection

Xue-Wei Zhang(张雪伟), Shao-Bin Liu(刘少斌), Qi-Ming Yu(余奇明), Ling-Ling Wang(王玲玲), Kun Liao(廖昆), and Jian Lou(娄健)   

  1. College of Electronic and Information Engineering, Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
  • 收稿日期:2021-12-07 修回日期:2022-02-13 接受日期:2022-03-23 出版日期:2022-10-17 发布日期:2022-10-17
  • 通讯作者: Shao-Bin Liu E-mail:plrg@nuaa.edu.cn,lsb@nuaa.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. U2141232, 62071221, and 62071442) and the Aeronautical Science Foundation of China (Grant No. 2019ZA037001).

Ultra-wideband surface plasmonic bandpass filter with extremely wide upper-band rejection

Xue-Wei Zhang(张雪伟), Shao-Bin Liu(刘少斌), Qi-Ming Yu(余奇明), Ling-Ling Wang(王玲玲), Kun Liao(廖昆), and Jian Lou(娄健)   

  1. College of Electronic and Information Engineering, Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
  • Received:2021-12-07 Revised:2022-02-13 Accepted:2022-03-23 Online:2022-10-17 Published:2022-10-17
  • Contact: Shao-Bin Liu E-mail:plrg@nuaa.edu.cn,lsb@nuaa.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. U2141232, 62071221, and 62071442) and the Aeronautical Science Foundation of China (Grant No. 2019ZA037001).

摘要: An ultra-wideband bandpass filter (BPF) with a wide out-of-band rejection based on a surface plasmonic waveguide (SPW) slotline with ring grooves is designed and analyzed. A paired microstrip-to-slotline transition is designed for quasi-TEM to TM mode conversion by using a microstrip line with a circular pad and the slotline with the same circular slot. The mode conversion between the TM and the surface plasmon polariton (SPP) mode is realized by using a gradient slotline with ring grooves and an impedance matching technique. The upper cut-off frequencies of the passband can be adjusted by using these proposed SPP units, while the lower frequencies of the passband are created by using the microstrip-to-slotline transitions to give an ultra-wideband BPF. The dispersion curves of SPP units, electric field distribution, and the transmission spectra of the proposed ultra-wideband bandpass filter are all calculated and analyzed by the finite-difference time-domain (FDTD) method. The simulated results show that the presented filter has good performance including a wide 3-dB bandwidth of 149% from 0.57 GHz to 3.93 GHz, an extremely wide 40-dB upper-band rejection from 4.2 GHz to 18.5 GHz, and low loss and high selectivity in the passband. To prove the design validity, a prototype of the BPF has been manufactured and measured, showing a reasonable agreement with simulation results. The unique features of the proposed BPF may make it applicable for integrated circuit and plasmonic devices in microwave or THz frequency ranges.

关键词: surface plasmonic waveguide (SPW), bandpass filter, out-of-band rejection, ultra-wideband

Abstract: An ultra-wideband bandpass filter (BPF) with a wide out-of-band rejection based on a surface plasmonic waveguide (SPW) slotline with ring grooves is designed and analyzed. A paired microstrip-to-slotline transition is designed for quasi-TEM to TM mode conversion by using a microstrip line with a circular pad and the slotline with the same circular slot. The mode conversion between the TM and the surface plasmon polariton (SPP) mode is realized by using a gradient slotline with ring grooves and an impedance matching technique. The upper cut-off frequencies of the passband can be adjusted by using these proposed SPP units, while the lower frequencies of the passband are created by using the microstrip-to-slotline transitions to give an ultra-wideband BPF. The dispersion curves of SPP units, electric field distribution, and the transmission spectra of the proposed ultra-wideband bandpass filter are all calculated and analyzed by the finite-difference time-domain (FDTD) method. The simulated results show that the presented filter has good performance including a wide 3-dB bandwidth of 149% from 0.57 GHz to 3.93 GHz, an extremely wide 40-dB upper-band rejection from 4.2 GHz to 18.5 GHz, and low loss and high selectivity in the passband. To prove the design validity, a prototype of the BPF has been manufactured and measured, showing a reasonable agreement with simulation results. The unique features of the proposed BPF may make it applicable for integrated circuit and plasmonic devices in microwave or THz frequency ranges.

Key words: surface plasmonic waveguide (SPW), bandpass filter, out-of-band rejection, ultra-wideband

中图分类号:  (Electromagnetic wave propagation; radiowave propagation)

  • 41.20.Jb
84.40.Dc (Microwave circuits) 84.40.Az (Waveguides, transmission lines, striplines) 73.20.Mf (Collective excitations (including excitons, polarons, plasmons and other charge-density excitations))