Liquid crystal microlenses based on binary surface alignment controlled by focused ion beam treatment

Abstract

We report the formation of high optical power microlenses in the near-surface region of the liquid crystal layer. Such microlenses, possessing a very small focal length f at a rather large aperture A ( f / A ∼ 2 ), are able to focus the light into spots of a characteristic size comparable with the wavelength. Using numerical modeling, a specific patterning profile of a liquid crystal (LC) alignment surface by an ion beam is proposed to provide the aligning properties necessary for the formation of an array of microlenses with a focal length comparable to the LC cell thickness. The proposed microlens arrays are produced, and their optical properties are discussed.

Liquid-crystal metasurfaces: Self-assembly for versatile optical functionality

“…In the first practical implementation of this idea [43], a binary aligning pattern with a feature size of 75 nm was designed to promote the LC assembly into a cylindrical lens of an aperture A = 15 μm (see fig. 5 Challenging functionalities.…”

“…Substituting photopatterning by treatment with tightly focused ion beam (FIB) not only has allowed stabilizing similar micrometer-scale LC textures [39][40][41], but also has drastically expanded the palette of patterns and decreased well below the visible light wavelength their minimum feature size. The metasurface design principles can now be applied to purely softmatter systems and the LC metasurfaces evolve [42,43]. Being controlled by low voltages, they retain the flat cell geometry, conventional for the LC display industry, which promises easy scaling up in production.…”

Waveguide Properties of Homogeneously Aligned Liquid Crystal Layers between ITO Electrodes and Thin Alignment Films

“…Along with well-known display applications, liquid crystals (LCs) are of great interest for various photonic devices. These are electrically controlled beam-steering devices and switched gratings [1,2], lenses and arrays of high-aperture lenses [3][4][5][6][7], liquid crystal metasurfaces [8][9][10], as well as liquid crystal light amplifiers and microlasers [11][12][13][14][15][16]. In many cases, the operation of these devices presupposes an effective waveguide mode of light propagation.…”