1. Department of Physics Malda College Malda 732101 India
2. Department of Physics Vidyasagar Teachers' Training College Midnapore 721101 India
3. Palacký University Olomouc Faculty of Science Joint Laboratory of Optics of Palacký University and Institute of Physics of the Czech Academy of Sciences 17. listopadu 1192/12 Olomouc 779 00 Czech Republic
4. Jaypee Institute of Information Technology A‐10, Sector‐62 Noida UP 201309 India