Fig. 1. Schematic diagram of the SP-HBS and LP-HBS. The grating comprises simple dielectric bars with high refractive index, surrounded by a low-index medium, herein, InP and air. T, HCG period; s, grating bar width; D, HCG duty cycle, D=s/T; t, HCG thickness.

Fig. 2. Schematic diagrams of designing an SP-HBS: (a) a basic grating unit, A-B-A; (b) the periodical extending of basic grating units; (c) a formed SP-HBS.

Fig. 3. Designed grating bars of SP-HBS and LP-HBS distributed on the X axis and their geometric structural parameters: (a) and (b) periods; (c) and (d) duty cycles.

Fig. 4. Transmissivity distributions and phase distributions of the grating bars used in SP-HBS and LP-HBS: (a) and (b) transmissivity distributions; (c) and (d) phase distributions.

Fig. 5. Simulation results of SP-HBS and LP-HBS for the normal incidence of a 1.55 μm TM-polarization Gaussian plane wave: (a) and (b) the electric-field intensity distributions, (d) and (e) the results by measuring the cut lines at y=0μm, 20 μm, and 40 μm in (a) and (b), with (a) and (d) for SP-HBS and (b) and (e) for the LP-HBS; the FWHM of incident light is 20 μm. (c) is the splitting effect of an SP-HBS with 9.9 μm width when the incident light (FWHM=5μm) propagates from the near- to far-field, and (f) is the measurement results by cutting (c) at y=30μm, 60 μm, and 90 μm.

Fig. 6. Simulation results of the SP-HBSs whose ΔφAB are (a) π, (b) 0.972π, (c) 0.892π, (d) 0.801π, (e) 0.5π, and (f) 0.001π. Insets are the normalized electric-field intensity of the cut line at y=40μm.

Fig. 7. Simulation results of SP-HBS for the small-angle (θi=5°) oblique incidence of a 1.55 μm TM-polarization Gaussian (FWHM = 5 μm) plane wave. The deflection angles of beams A and B are 52.3° and 38.1°, respectively.