Surface plasmon polaritons frequency-blue shift in low confinement factor excitation region |
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| Affiliation: | 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 |
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| 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. |
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| Keywords: | surface plasmon polaritons (SPPs) frequency-blue shift surface plasmon resonance (SPR) coherent enhancement radiation |
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