1. Laser
and Nonlinear Optics Laboratory, Department of Physics, National Institute of Technology, Calicut, Kozhikode 673601, Kerala, India
2. Department
of Physics, C K G M Government College, Perambra, Kozhikode 673525, Kerala, India
3. School
of Physics, University of Hyderabad, Gachibowli, Hyderabad 500046, India