Electrically switchable bright-field and interference-synthesized edge-enhanced imaging with a polarization-multiplexed metalens

Metasurface image processors are typically designed by prescribing a spatial-frequency transfer function in a single optical channel. Here, we demonstrate an LC-integrated polarization-dependent metalens that electrically accesses three transfer-function states by interferometrically synthesizing an effective response from two cofocal imaging channels. A voltage-controlled liquid-crystal (LC) cell selects X-polarized, Y-polarized, or 45° linearly polarized illumination at the metalens plane. The metalens encodes two polarization-selective focusing channels with unequally effective apertures and a common focal plane, producing a broad low-pass response and a narrower low-pass response. Under 45°-polarized illumination followed by a 45° polarization analyzer, both channels are projected onto a common basis. A designed π-phase offset suppresses shared low-spatial-frequency components through coherent cancellation, while higher spatial frequencies supported by the larger aperture are retained, yielding an interference-synthesized response. This interference-synthesized response produces edge-enhanced images without digital post-processing. Experiments at 635 nm validate the three states through focusing characterization, modulation-transfer analysis, resolution-target imaging, biological imaging, and LC-assisted electrical switching. This work establishes coherent channel interaction as a design principle for electrically reconfigurable metasurface transfer-function engineering.