Trapping and Precise Manipulation of Multi-absorbing Particles Based on Fiber Bessel-like Beam

We propose and demonstrate a multiple absorbing particles (APs) trapping and manipulation device based on a focused optical fiber Bessel-like beam. The fiber device utilizes the combination of single mode fiber (SMF) and multimode fiber (MMF) to generate a Bessel-like beam, which is focused by a glass sphere lens. This configuration enables the trapping of multiple APs within a liquid medium. The shape of the focused field is related to the position change of the glass sphere lens. By adjusting the position of the spherical lens, different beam distributions can be obtained, thereby generating different trapping points. When the glass sphere lens is placed along the optical fiber axis, APs are trapped along the optical axis of the fiber. When the spherical lens deviates from the axial direction of the fiber, trapping points of off-axis appears in the field. The trapping power required for APs varies with their position. In the experiment, we measured the trapping power of a single AP at different points and determined the power to achieve both axial and off-axis trapping of multiple APs. When the power varied uniformly, the velocity of APs passing through different positions is inconsistent, with their displacement trends changing regionally. It is worth noting when the lens is unshifted, the precise and controllable continuous movement range of the APs reaches approximately 70 μm, and is expected to play a positive role in biology, medicine and other fields.