Intensity-tunable transverse achromatic liquid crystal bifocal lens controlled through polarization

In this Letter, a transverse achromatic liquid crystal bifocal lens (ALCBLs) is proposed in which the relative intensity between the two foci can be controlled via polarization. The proposed device comprises three diffractive liquid crystal bifocal lenses fabricated using a specialized multi-twist (MT) structure, the transmittance for the target wavelength of all lenses can reach approximately 95%. Each lens focuses the left-circular polarized (LCP) and right-circular polarized (RCP) beams of the target wavelength (445, 520, and 638 nm) to different focal points. The proposed ALCBLs have a size of 2 mm and have been experimentally verified to effectively suppress chromatic aberration. Potential applications are expected to be found in augmented reality (AR) displays, multi-wavelength chiral imaging systems, and biomedical imaging applications.