Lithium niobate (LiNbO3) crystal exhibits exceptional electro-optic, acoustic-optic, and nonlinear-optic properties, establishing itself as a highly promising material platform for diverse applications in optical communication networks, microwave photonic systems, and quantum information processing. Our research focuses on the design and nanofabrication of essential lithium niobate components, including waveguides, microdisks, and linear/nonlinear photonic crystals. These components find applications in laser frequency conversion, quantum light generation, electro/acousto-optic modulators, and the development of surface acoustic wave (SAW) devices.

Femtosecond laser-writing methods have found extensive applications in the creation of three-dimensional (3D) photonic structures within transparent materials. Within our research group, we leverage a near-infrared femtosecond laser to conduct precise 3D nanoscale domain engineering in materials such as lithium niobate, lithium tantalate, and other ferroelectric crystals. The achieved resolution of 30 nm surpasses the conventional diffraction limit of light. Furthermore, we have pioneered a femtosecond laser-assisted nanolithography technique, enabling the realization of high-aspect-ratio nanofabrication specifically in lithium niobate crystals.

Nonlinear optics serves as a crucial tool for connecting diverse electromagnetic frequencies, facilitating communication across visible, infrared, and terahertz bands through χ(2) and higher-order nonlinear optical processes. Employing the principles of quasi-phase matching theory, our approach involves the utilization of nonlinear photonic crystals in lithium niobate (referred to as periodically poled lithium niobate crystals). These crystals feature intricately designed three-dimensional nanostructures that enable the manipulation of various dimensional parameters within a light field. These parameters include wavelength, polarization, spatial mode, orbital angular momentum (OAM), and quantum correlation. Our research extends the functionality to nonlinear beam shaping, nonlinear holography, high-dimensional quantum entanglement, and nonlinear neural network applications. Notably, ......

Laguerre-Gaussian modes represent eigen solutions of the paraxial Helmholtz equation, offering versatile capabilities across various applications. Notably, they serve as typical orbital angular momentum (OAM) modes, enhancing the precision of measuring rotational angles and speeds. The orthogonality inherent in these modes is harnessed for high-capacity holographic multiplexing. Laguerre-Gaussian modes form a comprehensive modal basis, extensively applied for analyzing both static and rotating light fields. Additionally, our research has led to the development of advanced techniques in quantum-enhanced phase measurement, single-pixel sensing, polarization detection, and optical artificial intelligence.