[1] TJS Engn Coll, Dept Phys, Peruvoyal 601206, India
[2] Anna Univ, Chennai 600025, Tamil Nadu, India
[3] RMK Engn Coll, Dept Phys, Kavaraipettai 601206, India
[4] RMD Engn Coll, Dept Phys, Kavaraipettai 601206, India
[5] Univ Madras, Loyola Coll Autonomous, Dept Phys, Chennai 600034, Tamil Nadu, India