Strongly Enhanced and Directionally Tunable Second-Harmonic Radiation by a Plasmonic Particle-in-Cavity Nanoantenna,
Xiong, Xiaoyan Y. Z., Jiang Li Jun, Sha Wei E. I., Lo Yat Hei, Fang Ming, Chew Weng Cho, and Choy Wallace C. H.
, Physical Review A, 11/2016, Volume 94, Issue 5, (2016)