Laser trapping and manipulation under focused evanescent wave illumination

A laser trapping technique was investigated under focused evanescent wave illumination. It was observed that the use of a sharp tip or a nanoaperture effected the nano-manipulation operation. The laser trapping was achieved for any size of the obstruction in the transverse direction. It was found that due to the circular symmetric nature of illumination, the resulting evanescent wave constructively interferes at the center of the focus, and enhance the strength of the evanescent field and thereby reducing the lateral trapping size. The results confirm that this technique provides a reduced trapping volume due to the fast decaying nature of the evanescent field.