Capillary-assisted self-assembly of glass microspheres for simple and versatile fabrication of voltage-tunable two-dimensional liquid crystal gratings

Abstract

We present a straightforward yet versatile method for fabricating voltage-tunable two-dimensional liquid crystal (LC) gratings that exhibit high diffraction efficiency and polarization independence. This technique employs capillary-assisted self-assembly of 5 μm silica microspheres on an indium tin oxide-coated glass substrate, resulting in a highly ordered hexagonal structure without requiring intricate lithography or templating processes. The self-assembled microsphere array effectively modulates the alignment of the LC, enabling tunable diffraction in response to applied voltages. Experimental findings demonstrate a first-order diffraction efficiency of 2.76% at 0 V, which decreases to 1.86% at 5 V and stabilizes at 2.41% at 15 V. Notably, the grating exhibits polarization-independent diffraction within the voltage range of 3–4 V. This approach significantly streamlines the fabrication process while delivering strong performance, paving the way for developing next-generation tunable LC optical devices.