1. Centre for Photonic Devices and Sensors, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
2. Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Lot 106, 108 & 110, Tingkat 1, Block A, Taman Pertiwi Indah, Jalan Kangar-Alor Setar, Seriab, 01000 Kangar, Perlis, Malaysia