Fig. 2

Principles of light field interactions with disordered NLC medium. a Simplified model composed of randomly LC directors arranged in a square lattice. Inset: Schematic of in-plane director angle \(\theta\) relating to the x-axis. b Simulated in-plane random distributions of NLC directors (left panel), and their far-field diffracted speckle patterns (right panel) with Gaussian beam input (waist radius of 1 mm). The ordinary refraction index and extraordinary refraction index of NLC medium are set as 1.517 and 1.741, respectively; and the NLC film thickness is set as 20 \(\upmu\)m. The scale bar is 2 mm. c Calculated structural similarity (SSIM) index of speckle patterns for various linear-polarization light input in a range of disorder strength (\(\varepsilon\)). d Calculated SSIM contrast for various disorder parameter (\(\varepsilon\)) under linear-polarization light input. e,f Simulated and experimental results of SSIM index of speckle patterns for different polarized light input (e) and different OAM-state input (f). The light wavelength is fixed as 660 nm. g Simulated and experimental results of SSIM for speckle patterns under different light wavelength input