ADJUSTABLE DEVICE FOR A GEOMETRIC-PHASE OPTICAL SHIFT, AND ADJUSTABLE METHOD OF GENERATING A GEOMETRIC-PHASE OPTICAL SHIFT

摘要

The invention relates to an adjustable device (103) for a geometric-phase optical shift, comprising: a nematic liquid-crystal film (4); a permanent magnet (5) comprising a through-passage (6), the permanent magnet (5) being suitable for generating a magnetic field around a magnetic axis (13) extending through the through-passage (6) and the magnetic field having a component that is transverse to the magnetic axis (13) and suitable for generating, in the liquid-crystal film (4), a structure with a topological charge +1, and the through-passage (6) being suitable for transmitting a light beam that passes through the liquid-crystal film (4); electrodes (2, 12) suitable for applying an electrical field to the liquid-crystal film (4), said electrical field being oriented transversely to the plates (1), wherein the electrical field and the magnetic field are suitable for generating, in the liquid-crystal film (4) a spiral-shaped geometric-phase optical shift about the magnetic axis (13).