中国物理B ›› 2021, Vol. 30 ›› Issue (8): 84102-084102.doi: 10.1088/1674-1056/abe22e

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Surface plasmon polaritons frequency-blue shift in low confinement factor excitation region

Ling-Xi Hu(胡灵犀)1,2, Zhi-Qiang He(何志强)1,2, Min Hu(胡旻)1,2,†, and Sheng-Gang Liu(刘盛纲)1,2   

  1. 1 Terahertz Research Center, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China;
    2 Key Laboratory of Terahertz Technology, Ministry of Education, Chengdu 610054, China
  • 收稿日期:2020-12-16 修回日期:2021-01-12 接受日期:2021-02-02 出版日期:2021-07-16 发布日期:2021-08-02
  • 通讯作者: Min Hu E-mail:hu_m@uestc.edu.cn
  • 基金资助:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0701000, 2018YFF01013001, and 2020YFA0714001) and the National Natural Science Foundation of China (Grant Nos. 61988102, 61921002, and 62071108).

Surface plasmon polaritons frequency-blue shift in low confinement factor excitation region

Ling-Xi Hu(胡灵犀)1,2, Zhi-Qiang He(何志强)1,2, Min Hu(胡旻)1,2,†, and Sheng-Gang Liu(刘盛纲)1,2   

  1. 1 Terahertz Research Center, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China;
    2 Key Laboratory of Terahertz Technology, Ministry of Education, Chengdu 610054, China
  • Received:2020-12-16 Revised:2021-01-12 Accepted:2021-02-02 Online:2021-07-16 Published:2021-08-02
  • Contact: Min Hu E-mail:hu_m@uestc.edu.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0701000, 2018YFF01013001, and 2020YFA0714001) and the National Natural Science Foundation of China (Grant Nos. 61988102, 61921002, and 62071108).

摘要: Surface plasmon polaritons' (SPPs') frequency blue shift is observed in finite-difference time-domain (FDTD) simulation of parallel electron excitation Au bulk structure. Comparing with cold dispersion of SPPs, an obvious frequency blue shift is obtained in low confinement region excitation simulation results. Then, according to SPPs' transverse attenuation characteristics, the excited frequency mode instead of cold dispersion corresponding frequency mode matches it. Thence, this excited mode is confirmed to be SPPs' mode. As is well known the lower the frequency, the smaller the confinement factor is and the lower the excitation efficiency, the wider the bandwidth of excited SPPs is. And considering the attenuation in whole structure, the excited surface field contains attenuation signal. In a low confinement factor region, the higher the SPPs' frequency, the higher the excitation efficiency is, while broadband frequency information obtained in attenuation signal provides high frequency information in stimulation signal. Thence, in the beam-wave interaction, as the signal oscillation time increases, the frequency of the oscillation field gradually increases. Thus, compared with cold dispersion, the frequency of excited SPP is blueshifted This hypothesis is verified by monitoring the time domain signal of excited field in low and high confinement factor regions and comparing them. Then, this frequency-blue shift is confirmed to have commonality of SPPs, which is independent of SPPs' material and structure. Finally, this frequency-blue shift is confirmed in an attenuated total reflection (ATR) experiment. Owing to frequency dependence of most of SPPs' devices, such as coherent enhancement radiation and enhancement transmission devices, the frequency-blue shift presented here is of great influence in the SPPs applications.

关键词: surface plasmon polaritons (SPPs), frequency-blue shift, surface plasmon resonance (SPR), coherent enhancement radiation

Abstract: Surface plasmon polaritons' (SPPs') frequency blue shift is observed in finite-difference time-domain (FDTD) simulation of parallel electron excitation Au bulk structure. Comparing with cold dispersion of SPPs, an obvious frequency blue shift is obtained in low confinement region excitation simulation results. Then, according to SPPs' transverse attenuation characteristics, the excited frequency mode instead of cold dispersion corresponding frequency mode matches it. Thence, this excited mode is confirmed to be SPPs' mode. As is well known the lower the frequency, the smaller the confinement factor is and the lower the excitation efficiency, the wider the bandwidth of excited SPPs is. And considering the attenuation in whole structure, the excited surface field contains attenuation signal. In a low confinement factor region, the higher the SPPs' frequency, the higher the excitation efficiency is, while broadband frequency information obtained in attenuation signal provides high frequency information in stimulation signal. Thence, in the beam-wave interaction, as the signal oscillation time increases, the frequency of the oscillation field gradually increases. Thus, compared with cold dispersion, the frequency of excited SPP is blueshifted This hypothesis is verified by monitoring the time domain signal of excited field in low and high confinement factor regions and comparing them. Then, this frequency-blue shift is confirmed to have commonality of SPPs, which is independent of SPPs' material and structure. Finally, this frequency-blue shift is confirmed in an attenuated total reflection (ATR) experiment. Owing to frequency dependence of most of SPPs' devices, such as coherent enhancement radiation and enhancement transmission devices, the frequency-blue shift presented here is of great influence in the SPPs applications.

Key words: surface plasmon polaritons (SPPs), frequency-blue shift, surface plasmon resonance (SPR), coherent enhancement radiation

中图分类号:  (Radiation by moving charges)

  • 41.60.-m
41.60.Bq (Cherenkov radiation) 41.85.-p (Beam optics) 11.55.Fv (Dispersion relations)