Surface plasmon polariton waveguides with subwavelength confinement<xref rid="cpb_27_9_094216fn1" ref-type="fn">*</xref><fn id="cpb_27_9_094216fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant Nos. 11704266 and 11774245), the Fok Ying Tung Education Foundation, China (Grant No. 151010), the Scientific Research Base Development Program of Beijing Municipal Commission of Education, China, the General Foundation of Beijing Municipal Commission of Education, China (Grant No. KM201810028006), and the Training Program of the Major Research Plan of Capital Normal University, China.</p></fn>

Surface plasmon polariton waveguides with subwavelength confinement**

Project supported by the National Natural Science Foundation of China (Grant Nos. 11704266 and 11774245), the Fok Ying Tung Education Foundation, China (Grant No. 151010), the Scientific Research Base Development Program of Beijing Municipal Commission of Education, China, the General Foundation of Beijing Municipal Commission of Education, China (Grant No. KM201810028006), and the Training Program of the Major Research Plan of Capital Normal University, China.

Yang Longkun¹, Li Pan¹, Wang Hancong², Li Zhipeng^{1, †}

(color online) (a) SEM image of the groove milled in a gold film. (b) CPPs launched by end-fire configuration. (c) Microscope image of the near-field optical probe. (d) SNOM images recorded at different wavelengths, in the range of 1425–1630 nm. (e) CPP dispersion: the CPP propagation length as a function of light wavelength. Insets show the electric field distributions of the fundamental CPP modes at different wavelengths. (f) Optical signal recorded inside the groove as a function of the distance between the probe and the bottom of the groove, together with the exponential fitting curves (dash lines), reproduced from Ref. [59]. (g) Near-field optical images taken at 1600 nm: (I) S-bends and (II) Y-splitter, reproduced from Ref. [62].