Linearly polarized high sub-mode excited long-beaked fiber optic transmission and tracking particulate system

Micro/nano optical fibers are playing an increasingly important role in the fields of targeted drug therapy and biological cell analysis. To achieve fast and stable particle delivery, we designed a long beak-shaped fiber probe that not only increases the fiber optical field gradient force but also enhances the evanescent field around the probe. The evanescent field at the side of the fiber is further enhanced by exploiting the symmetrically distributed four-wave flap mode field of the linearly polarized high sub-mode in the weakly guided fiber, thus ensuring stable particle capture in the axial direction while improving the stability of lateral capture. We conducted a series of experiments using a long-beaked micro-nano fiber in LP21 mode to deliver polystyrene particles, and the results show that the probe can deliver particles rapidly at low input power, verifying the superiority of the long-beaked fiber probe. Finally, we built an FPI interference model to monitor the transport position of the particles in real-time. By processing the interference fringes, we plotted the motion profile of the particles, which helps to further manipulate the motion of the particles.