1. Fiber Optics & Photonics Division, CSIR-Central Glass & Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata 700032, India
2. Raman Centre for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science (IACS), 2A & 2B Raja S C Mullick Road, Kolkata 700032, India
3. Material Characterization Division, CSIR-Central Glass & Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata 700032, India