1. Electrical Engineering Department, Stanford University, 350 Serra Mall, Stanford, California 94305, United States
2. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
3. Physical Science and Engineering Division, KAUST Solar Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia