Vortex beam generator based on single-layer porous metasurface

The coupling of multi-channel optical vortices based on angular momentum conservation using a single-layer metal metasurface

“…The modulation of the phase of the optical field by the resonant metasurface completely depends on the resonance of the nanostructure itself, so the working bandwidth of the resonant metasurface is often very narrow [19][20][21]. The other type of metasurface is the geometric phase metasurface using the Pancharatnam-Berry (PB) phase, which can obtain different phases by changing the rotation angle of the structural unit [22][23][24]. Compared with the resonant metasurface, the geometric phase metasurface does not require the strict design of structural parameters, which is more flexible and can ensure that the outgoing beam amplitude is maintained at the same amplitude.…”