Miniaturized Dual-Beam Optical Trap Based on Fiber Pigtailed Focuser

Optical traps, utilizing a laser to confine and manipulate microscopic particles, are widely employed in various scientific applications. We propose a miniaturized dual-beam fiber optical trap for acceleration sensing. It comprises two counter-propagating beams’ output from a customized pair of single-mode fiber pigtailed focusers (SMFPF). We investigate the correlation between the misalignment and the coupling efficiency of the SMFPF pair. By maximizing the coupling efficiency, the optimal alignment is achieved. A multimode fiber (MMF) is introduced to collect and transmit side-scattered light of a trapped microsphere for motion detection. By analyzing the experimental output signal, we acquire displacement information of the trapped microspheres under both aligned and misaligned conditions. This paper provides a simple and practical solution for the alignment of dual beams and the integration of the optical traps’ levitation and detection structure, which lay a solid foundation for the further miniaturization of dual-beam optical traps.