1. Quantum Engineering Laboratory, Department of Physics, Tamkang University, Tamsui, New Taipei 25137, Taiwan
2. Department of Physics, R.O.C. Military Academy, Kaohsiung 830, Taiwan
3. Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
4. Center of General Studies, National Kaohsiung Marine University, Kaohsiung 811, Taiwan