1. Department of Electric Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37212, United States
2. Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
3. Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37212, United States
4. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States