Affiliation: | a Quantum Photonic Science Research Center and Department of Physics, Hanyang University, Seoul 133-791, Korea b International Training Institute of Materials Science (ITIMS), Hanoi University of Technology, Vietnam c Institute of Materials Science, Vietnamese Academy of Science and Technology, Hanoi, Vietnam d Department of Physics and Astronomy, K. U. Leuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium |