Hou, Chong
Jia, Xiaoting
Wei, Lei
Tan, Swee-Ching
Zhao, Xin
Joannopoulos, John D.
Fink, Yoel
Article History
Received: 8 August 2014
Accepted: 9 January 2015
First Online: 20 February 2015
Competing interests
: The authors declare no competing financial interests.