Fig. 1. Localized hybrid phonon resonance of Ge grating on SiC. (a) SEM image of the grating (w=2μm and P=4μm). Scale bar equals 4μm. (b) Measured absorption spectrum of gratings in (a) and its double-Lorentzian fittings. Simulated intensity distribution of the (c) dipolar and (d) higher order mode. White dashed lines indicate the SiC–air interface. Scale bar equals 4μm. (e) and (f) Percentage of total energy localized within a distance d above the SiC surface in the total energy above the SiC surface.

Fig. 2. Coupling of the propagating SPhP mode with the hybrid phononic–dielectric dipolar mode in Ge gratings with varying period P and fixed width (w=2μm): (a) experimental normalized absorption and (b) simulated normalized absorption. The yellow, magenta, and green dashed lines indicate phase-matching conditions of SPhP modes with m=−1, 1, and −2, respectively. (c) Absorption of the grating when w=2μm and P=8μm. Shaded areas represent multi-Lorentzian decomposition of the spectrum. Purple dots and blue lines represent experimental data and the fitted spectrum, respectively. (d)–(f) Real parts of the Ez for the green, magenta, and red dots shown in (b), respectively. The scale bar represents 2μm.

Fig. 3. Coupling of the propagating SPhP mode with the hybrid phononic–dielectric dipolar mode in Ge gratings with varying period P and fixed width (w=1μm): (a) experimental normalized absorption and (b) simulated normalized absorption. The yellow and magenta dashed lines indicate the phase-matching condition of SPhP mode with m=−1 and 1, respectively.