1. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2. Laboratory for Electro-Optics Systems, Indian Space Research Organization, Bangalore 560058, India
3. Sandia National Laboratories, P.O. Box 5800, MS-1086, Albuquerque, New Mexico 87185, USA
4. Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, New Mexico 88003, USA