Lithium niobate (LN), known as the “silicon of photonics,” exhibits outstanding material characteristics with great potential for broad applications. Enhancing light–matter interaction on the nanoscale would result in intriguing device characteristics that enable new physical phenomena to be revealed and novel functionalities inaccessible by conventional means to be realized. High‐Q 2D photonic crystal (PhC) slab nanoresonators are particularly suitable for this purpose, which, however, remains an open challenge to be realized on the lithium niobate platform. Here, an important step is taken toward this direction, demonstrating 2D LN PhC slab nanoresonators with optical Q as high as 3.51 × 105, about three orders of magnitude higher than other 2D LN PhC structures reported to date. The high optical quality, tight mode confinement, together with specific polarization characteristics of the devices enable the peculiar anisotropy of photorefraction quenching and unique anisotropic thermo‐optic nonlinear response to be revealed. They also allow the observation of third‐harmonic generation in on‐chip LN nanophotonic devices, and a strong orientation‐dependent generation of the second harmonic.
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Liquid crystals offer a dynamic platform for developing advanced photonics and soft actuation systems due to their unique and facile tunability and reconfigurability. Achieving precise spatial patterning of the liquid crystal alignment is critical to developing electro‐optical devices, programmable origami, directed colloidal assembly, and controlling active matter. Here, a simple method is demonstrated to achieve continuous 3D control of the directions of liquid crystal mesogens using a two‐step photo‐exposure process. In the first step, polarized light sets the orientation in the plane of confining substrates; the second step uses unpolarized light of a prescribed dose to set the out‐of‐plane orientation. The method enables smoothly varying orientational patterns with sub‐micrometer precision. As a demonstration, the setup is used to create gradient‐index lenses with parabolic refractive index profiles that remain stable without external electric fields. The lenses' focal length and sensitivity to light polarization are characterized through experimental and numerical methods. The findings pave the way for developing next‐generation photonic devices and actuated materials, with potential applications in molecular self‐assembly, re‐configurable optics, and responsive matter.
more » « less- NSF-PAR ID:
- 10494629
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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