We prescribe a novel approach for continuously tailoring the local phase of the nonlinear polarizability which can lead to an arbitrary phase profile for harmonic generations. The introduced phase of the nonlinear polarizability is inherently a geometric Berry phase arising from the spin rotation coupling of light in the nonlinear regime. This approach provides new routes for controlling the optical nonlinear processes.
Continuously Red-Shift and Blue-Shift Wavelength-Tuneable, Narrowband, High Harmonics in the EUV - X-ray Regime for Resonance Imaging and Spectroscopies
Continuous wave second harmonic generation enabled by quasi-bound-states in the continuum on gallium phosphide metasurfaces
共振超颖表面是一个有吸引力的平台，用于增强非线性光学过程，如二次谐波产生（SHG），因为它们可以产生非常大的局部电磁场，同时放松相位匹配的要求。在这里，我们通过演示可见范围的连续波（CW）SHG，使该平台更接近实际应用。我们这样做是通过结合有吸引力的材料特性的磷化镓工程，高品质因数的光子模式，使在连续的束缚态。对于最佳情况，当泵浦波长为1200 nm，连续光强为1 kW/cm $^2$时，系统的效率约为5e-5% W $^{-1}$.此外，我们测量的外部效率高达0.1% W $^{-1}$与泵的强度只有10 MW/cm $^2$的脉冲照射。该效率高于先前报道的电介质超颖表面的值，但在这里实现的泵浦强度低两个数量级。
Polar enhancement of optical nonlinearities and domain-driven second harmonic contrast in bismuth telluro-halide van der Waals crystals
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Columbia University（哥伦比亚大学）；Rutgers University（罗格斯大学）；Iowa State University（爱荷华州立大学）；Intellectual Ventures（智识风险投资）
A Thermal Modeling Toolkit for Continuous-Wave Gaussian Second-Harmonic Generation in KTP Crystal
Bowling Green State University（鲍灵格林州立大学）；Shahid Chamran University of Ahvaz（阿瓦士沙希德·恰姆兰大学）；University of New Hampshire（新罕布什尔大学）；Amirkabir University of Technology（阿米尔卡比尔理工大学）；Concordia University（康考迪亚大学）
Harmonics of femtosecond and continuous-wave radiation for precision spectroscopy: generation efficiency and spectral line shape
P.N. Lebedev Physical Institute of the Russian Academy of Sciences（俄罗斯科学院列别杰夫物理研究所）；Moscow Institute of Physics and Technology（莫斯科物理技术学院）；Russian Quantum Center（俄罗斯量子中心）
Treatment of Linear and Nonlinear Dielectric Property of Molecular Monolayer and Submonolayer with Microscopic Dipole Lattice Model: I. Second Harmonic Generation and Sum-Frequency Generation
