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Tunable Raman scattering enhancement via particle‐waveguide coupling
Author(s) -
Kan Xuefen,
Yin Cheng,
Wu Jian,
Li Bowei,
Han Qingbang
Publication year - 2019
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.5593
Subject(s) - raman scattering , materials science , raman spectroscopy , waveguide , coupling (piping) , excitation , scattering , surface plasmon resonance , substrate (aquarium) , nanoparticle , penetration depth , optoelectronics , optics , nanotechnology , physics , composite material , oceanography , quantum mechanics , geology
Surface‐enhanced Raman scattering relies crucially on the formation of hot spots, which are usually difficult to fabricate and modulate. In this paper, the reverse symmetrical waveguide structure (RSW) is applied as the Raman scattering enhancement substrate, whereas gold nanoparticles are mixed with sample solution to achieve the effective coupling between localized surface plasmon (LSP) and the guided modes. Experimental results verify that the reverse symmetry results in a large penetration depth of the guided modes into the covering medium at resonance; thus, the coupling of waveguide modes can promote the resonant strength of the LSP of the nanoparticles. In return, the excitation of the nanoparticles also facilitates the coupling of incident energy into the guided modes. Finally, the Raman enhancement can be effectively adjusted by tuning the coupling efficiency of the waveguide. We illustrate such modulation by varying the guiding layer thickness, and the experimental results fit well with the theoretical model.