Fig. 1. Refraction of an optical VB by an SMCW chip and the E-field distribution of an oscillating UOM at resonance (red line).

Fig. 2. (a) Optical field of the incident beam generated by a spiral phase plate with l = 1. (b), (c), and (d) Optical field of the reflected beam at 9.42, 9.50, and 9.52 deg, respectively. The intensity is normalized to the maximum of the incident light spot.

Fig. 3. (Top) Experimentally measured reflectivity of a VB reflected by the SMCW chip; (bottom) numerically simulated reflectivity of a planar wave model via the transfer matrix method. The permittivity of silver is based on the Drude model ε_Ag = −13.9235 + 0.7233i, and the permittivity of the guiding layer is 2.25.

Fig. 4. Evolution of the M-line in a reflected Gaussian beam under the same experimental conditions. The coupling angle of the resonant dip is around 9.13 deg. The intensity is normalized to the maximum of the reflected light spot in (b).

Fig. 5. Reflection spectra of a prism-coupled SMCW chip as a function of film thickness and incident angle. θ_c is the critical angle for total reflection of the guiding layer.

Fig. 6. (a) Phase structure and related energy flux S⇀ distribution (black arrow) in the beam cross sections at different propagation distances. (b) The distribution of the energy flux vector (red arrow) at a tilted cross section (blue circle) due to a nonzero incident angle θ.

Fig. 7. Simulated inner ring and the M-line of the reflected VB (l = 1) near a resonance, where the parameters are the same as those used in Fig. 3. The beam waist is 0.5 mm, and the propagation distance is z = 50 cm.

Fig. 8. (a), (d) Intensities and (b), (e) phase structures of the reflected beams with different topological charge l; (c), (f) the phase structures of the incident beams are also plotted for comparison. The incident angle is θ = 30 deg, and the rest parameters are the same as those used in Fig. 7.