1. Department of Physics and Astronomy and the Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
2. Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
3. Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
4. Laser Center, University of Latvia, Riga, LV-1004, Latvia
5. Department of Mathematics, Statistics, and Physics, Wichita State University, Wichita, Kansas 67260, United States