Fig. 1. (a) Schematic of THG from the silica-based metasurface; (b) a top-view scan electron microscope image of the metasuface; (c) the schematic diagram of the L-shaped resonators; (d) illustration of experimental set-up.(a)硅基超构表面中的三次谐波激发; (b)结构正面的扫描电子显微镜图像; (c)共振单元的尺寸示意图; (d)光路系统示意图

Fig. 2. (a) Reflection and transmission spectra of the metasurface in the wavelength range of 1530−1560 nm (T, transmission spectrum; R, reflection spectrum); (b) THG signal peak when the pump wavelength coincides with the resonant wavelength at 1548 nm; (c) power dependence of THG intensity; (d) spatial scanning of THG intensity distribution; (e) spectra of THG signals pumped with different wavelengths, and the inset shows the result of normalizing each line; (f) integral results for all THG spectra shown in panel (e).(a)超构表面在1530−1560 nm范围内的反射和透射光谱(T, 透射谱; R, 反射谱); (b)抽运波长与共振波长(1548 nm)重合时产生的THG信号峰; (c) THG信号相对于抽运光的功率依赖性; (d) THG强度分布的空间扫描; (e)不同抽运波长下THG信号的光谱演化, 插图为对谱线进行归一化后的结果; (f)对(e)中所有THG信号谱线进行能量积分的结果

Fig. 3. (a) Numerical simulation of the distribution of electric field of the metasurface in the x-y plane; (b) numerical simulation of the anisotropic transmission spectra of the sample; (c) numerical simulation of reflection (R), transmission (T) spectra and intensity of THG signals. (a)左图为超构表面电场在x-y平面内分布情况的数值模拟, 右图为单共振单元横向的电场分量(右上)和纵向的磁场分量(右下); (b)样品各向异性透射谱的数值模拟; (c)透射、反射信号以及THG信号强度的数值计算结果

Fig. 4. (a) Orientation illustrated in the metasurface; (b) experimental measurement of polarization dependence of transmitted and reflected signals; (c) experimental measurement of the polarization dependence of THG signal intensity on pump light; (d) polarization detection of THG signals.(a)方位示意图; (b)实验测量透射/反射信号的偏振依赖性; (c)实验测量THG信号强度对抽运光的偏振依赖性; (d) THG 信号的偏振检测