Spectral broadening in silicon is studied numerically as well as experimentally. Temporal dynamics of the free carriers generated during the propagation of optical pulses, through the process of two-photon absorption (TPA), affect the amplitude and phase of the optical pulses, thereby determining the nature and extent of the generated spectral continuum. Experimental results are obtained by propagating pico-second optical pulses in a silicon waveguide for intensities that span two orders of magnitude (1-150 GW/cm2). These results validate the conclusions drawn from numerical simulations that the continuum generation has a self-limiting nature in silicon.
High-efficiency infrared upconversion imaging with nonlinear silicon metasurfaces empowered by quasi-bound states in the continuum
Nanchang University（南昌大学）；Institute for Advanced Study, Nanchang University（南昌大学高等研究院）；School of Education, Nanchang Institute of Science and Technology（南昌理工学院教育学院）；Guangdong Polytechnic Normal University（广东技术师范大学）
Room-temperature polariton repulsion and ultra-strong coupling for a non-trivial topological one-dimensional tunable Fibonacci-conjugated porous-Silicon photonic quasi-crystal showing quasi bound-states-in-the-continuum
Robust enhancement of high-harmonic generation from all-dielectric metasurfaces enabled by polarization-insensitive bound states in the continuum
新兴的全电介质平台表现出高质量（$Q$）共振，其由驱动高效非线性光学过程的连续体（BIC）中的束缚态物理所支配。在这里，我们展示了强大的增强三次谐波（THG）和五次谐波产生（FHG）从由四个硅纳米盘组成的全介电超颖表面。通过对称性破缺，真正的BIC转变为具有紧密场约束的高$Q$准BIC共振，以使用1 GW/cm $^{2}$的中等泵浦强度来实现$3.9\times10^{-4}$ W $^{-2}$的创纪录的高THG效率和$4.8\times10^{-10}$ W $^{-4}$的FHG效率。此外，准BIC和共振增强谐波表现出偏振不敏感的特性，由于特殊的$C_{4}$排列的元原子。我们的研究结果为智能设计高效、鲁棒的非线性纳米光子器件提供了思路。
Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum
