1. Research & Development Centre; Bharathiar University; Coimbatore 641 046 Tamil Nadu India
2. Faculty of Physics; Dr. Mahalingam College of Engineering and Technology; Pollachi 642 003 Tamil Nadu India
3. Department of Physics; Sri Ramakrishna Mission Vidyalaya College of Arts and Science; Coimbatore 641 020 Tamil Nadu India
4. School of Electrical Engineering; Pusan National University; Busan 609 735 Republic of Korea