Figure 1 | Nonlinear Pancharatnam-Berry phase (IMAGE)
Caption
Figure 1 | Nonlinear Pancharatnam-Berry phase. a, A thin-film polar LC element with a spatially modulated alignment pattern in the x-y plane. The right panel: a polar LC director in the (x, y, z) coordinate system. The azimuthal angle in the x-y plane is denoted as . For a polar LC director, SHG signals of both circular polarizations, with phases of σα and 3σα, are generated in the forward direction. b, Schematic representation of the linear and nonlinear Pancharatnam-Berry phases resulting from coordinate transformations. The entire diagram is divided into a central part representing the local frame with blue coordinate axes and an outer part representing the laboratory coordinates with black coordinate axes. The area under the blue-violet trapezoidal shadow on the left corresponds to the linear optical process, while the other gradient-colored trapezoidal region includes the process of nonlinear frequency conversion. For a CP FW incidence with the spin state of σ = +1 (RHCP), the evolved cross-CP FW signal acquires Pancharatnam-Berry phase of 2σα, while the co- and cross-CP components of the SH signal acquire nonlinear Pancharatnam-Berry phases σα and 3σα, respectively.
Credit
Hui-Feng Chen et al.
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License
CC BY