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Abstract Optical vortex beams with helical phase fronts have immense potential to enhance data capacity due to the unbounded values of orbital angular momentum. Chip‐scale platforms for producing vortex beams are of paramount importance for a variety of applications. On the other hand, 2D materials with unique optical properties are essential for developing multifunctional ultrathin photonic devices. Here, anisotropic and temperature‐tunable second‐harmonic vortex beam generation is demonstrated with ultrathin ferroelectric niobium oxide dichloride (NbOCl₂) fork holograms. The polarization‐resolved Raman measurements are performed on the NbOCl₂crystal to understand the anisotropic behavior of the Raman modes. It is demonstrated that the anisotropic and temperature‐tunable second‐harmonic vortex beams can be generated regardless of the relative orientation of the fork gratings with respect to the crystallographic orientation of the NbOCl₂flakes. Furthermore, the Curie temperature of the ferroelectric NbOCl₂crystal is determined according to the measured temperature‐dependent second‐harmonic generation intensities. The results presented here create new opportunities for the development of advanced polarization‐sensitive and temperature‐switchable nonlinear photonic devices used for future applications in integrated photonic devices, quantum optical chips, and optical communication. 

The coherent superposition of two vortex beams with opposite topological charges gives rise to the formation of petal‐like beams with unique intensity profiles and azimuthal phase structures, offering great potential for various applications. Here, the generation of anisotropic second‐harmonic petal‐like beams is demonstrated using ultrathin niobium oxide dibromide (NbOBr₂) holograms. The polarization‐dependent Raman measurements are conducted on the NbOBr₂flake to reveal the anisotropic properties of the crystal. By imprinting the beam profile information of the superposed vortex beams on the designed NbOBr₂holograms, highly anisotropic second‐harmonic petal‐like beams with different combinations of the topological charges of vortex beams are produced. The results demonstrated here provide a pathway toward the development of chip‐scale polarization‐sensitive functional optical devices for applications in optical communication, optical trapping, and quantum optics. 

Hermite–Gaussian (HG) modes are an orthogonal set of solutions to the paraxial wave equation possessing distinct spatial intensity variations, which are important in many optical applications. Here, anisotropic second‐ and third‐harmonic HG beam generation is demonstrated with ultrathin niobium oxide diiodide (NbOI₂) grating holograms to produce the nonlinear HG₀₁and HG₁₀modes. It is shown that the generated second‐harmonic HG modes exhibit a high anisotropy ratio reaching a large value of 14.95, while the simultaneously generated third‐harmonic HG modes have an anisotropy ratio up to 4.85. The relative magnitudes of the second‐ and third‐order nonlinear susceptibility tensor elements of NbOI₂crystal are extracted by analyzing the polarization‐dependent nonlinear emission. These demonstrations provide new opportunities for building functional polarization‐sensitive nonlinear optical devices used for future integrated photonic chips, optical computing, and optical communication.