Converging lasing from floating GaN Penrose microcavityGangyi Zhu, Siqing He, Mengyao Zhou, Guoqing Qiu, Ming Fang, Jialei Yuan, Jitao Li and Yongjin WangEPL, 127 2 (2019) 24001DOI: https://doi.org/10.1209/0295-5075/127/24001