1. Department of EEE, Bangladesh University of Engineering & Technology, Dhaka, Bangladesh;2. Department of Electrical and Computer Engineering (ECE), National University of Singapore, Singapore
Abstract:
In this article, we have theoretically demonstrated the mechanism of an active tractor beam for multiple fully immersed objects with additional abilities to yielding stable long distance levitation, a controlled rotation and a desired 3D trapping. This is demonstrated with a single optical set‐up by using two coaxial, or even non‐coaxial, superimposed higher order monochromatic Bessel beams of reverse helical nature and different frequencies. The superimposed beams can possess periodic intensity variations both along and around the beam‐axis due to a difference in longitudinal wave‐numbers and beam orders, respectively. The difference in frequencies of the two laser beams makes the intensity pattern to move along and around the beam‐axis in a continuous way without manual ramping of phase, which allows for bidirectional movement of completely immersed multiple particles. The condition for increasing or decreasing the dimension of binding regions is also proposed here to manipulate multiple immersed objects of different sizes under dipole approximation.
