Vertical-Cavity Surface-Emitting Laser With a Chiral Nematic Liquid Crystal Overlay Volume 6, Number 1, February 2014 Y. Xie, Member, IEEE J. Beeckman K. Panajotov K. Neyts DOI: 10.1109/JPHOT.2013.2294632 1943-0655 Ó 2013 IEEE