1. Fiber Optic Sensor Lab, Department of Physics, National Institute of Technology Tiruchirappalli, Tiruchirappalli 620 015, Tamil Nadu, India
2. Centre for Nanoscience and Nanotechnology, International Research Centre, Sathyabama Institute of Science and Technology, Jeppiar Nagar, Chennai 6000119, India
3. Department of Electronics and Communication Systems, Sri Krishna Arts and Science College, Coimbatore 641 008, Tamil Nadu, India