@article {1312421, title = {Metasurface-assisted phase-matching-free second harmonic generation in lithium niobate waveguides}, journal = {Nature Communications}, volume = {8}, number = {2098}, year = {2017}, author = {Wang, Cheng and Zhaoyi Li and Myoung-Hwan Kim and Xiao Xiong and Xi-Feng Ren and Guang-Can Guo and Nanfang Yu and Lon{\v c}ar, Marko} }