Doubly resonant photonic crystal cavity using merged bound states in the continuum

作     者：Rui Ge Xiangmin Liu Xiongshuo Yan Xianfeng Chen Yuping Chen 

作者机构：State Key Laboratory of Advanced Optical Communication Systems and Networks School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal University Jinan 250358 China 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2023年第107卷第16期

页      面：165406-165406页

核心收录：

基　　金：National Natural Science Foundation of China, NSFC, (12134009, 91950107) National Natural Science Foundation of China, NSFC Science and Technology Commission of Shanghai Municipality, STCSM, (2019SHZDZX01-ZX06) Science and Technology Commission of Shanghai Municipality, STCSM Shanghai Jiao Tong University, SJTU, (21X010200828) Shanghai Jiao Tong University, SJTU National Key Research and Development Program of China, NKRDPC, (2019YFB2203501) National Key Research and Development Program of China, NKRDPC 

主　　题：Nanophotonics Photonic crystals 

摘      要：In this work, a doubly resonant photonic crystal (PhC) cavity using the merged bound state in the continuum (BIC) is proposed to obtain a higher second harmonic generation (SHG) efficiency. First, by scanning geometry parameters, the accidental BICs and a band-edge mode outside the light cone can be obtained. Then, as the lattice constant or the thickness of the slab is adjusted, the accidental BICs will merge. A supercell with large and small holes is constructed and the band-edge mode outside the light cone can be matched with the merged BIC mode. Finally, the heterostructure PhC cavity is designed. The merged BIC show a high quality factor of about 2000 for the PhC with finite size. The value is four times larger than the one in isolated BIC (about 500). Consequently, the SHG efficiency of the lattice constant near merged BIC of about 4800% W−1 is higher than the one of the isolated BIC (about 1000% W−1). This work is expected to provide guidance to the efficient nonlinear conversion in a small volume.