论文标题
从连续体中的界面状态下的双重共鸣的第二次谐波产生
Doubly resonant second-harmonic generation of a vortex beam from a bound state in the continuum
论文作者
论文摘要
通过实现具有高质量因素的双共振腔，可以大大增强非线性材料中的第二次谐波产生。但是，在光子晶体（PHC）腔中实现这种双重共振状态是一个长期存在的挑战，因为在两个频率周围的工程光子带镜上都难以进行。在这里，通过在连续体（BIC）中实现第二次谐波状态并将其限制在异质结构设计中，我们显示了第一个双重共振的PHC平板腔，$ 2.4 \ times10^{ - 2} $ W $ w $^$^{ - 1} $转换在连续波动下的转化效率。我们还报告了在第二个谐波频率下具有径向极化的高正常方向浓缩远场发射模式的确认。这些结果代表了对先前理论预测和基石成就的可靠验证，这不仅是非线性频率转换，而且对于涡流束的产生和前瞻性非经典辐射来源。
Second harmonic generation in nonlinear materials can be greatly enhanced by realizing doubly-resonant cavities with high quality factors. However, fulfilling such doubly resonant condition in photonic crystal (PhC) cavities is a long-standing challenge, because of the difficulty in engineering photonic bandgaps around both frequencies. Here, by implementing a second-harmonic bound state in the continuum (BIC) and confining it with a heterostructure design, we show the first doubly-resonant PhC slab cavity with $2.4\times10^{-2}$ W$^{-1}$ conversion efficiency under continuous wave excitation. We also report the confirmation of highly normal-direction concentrated far-field emission pattern with radial polarization at the second harmonic frequency. These results represent a solid verification of previous theoretical predictions and a cornerstone achievement, not only for nonlinear frequency conversion but also for vortex beam generation and prospective nonclassical sources of radiation.
