Laser and nonlinear/quantum optics

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, we have developed Janus laser and optical parametric oscillator (OPO) systems capable of producing high-efficiency, high-purity, and high-order Laguerre-Gaussian modes.