Higher-order Micro-fiber Modes for Escherichia coli Manipulation Using Tapered Four-mode Fiber

A large diameter fiber-optics tweezers was proposed and demonstrated for trapping and delivering E. coli bacteria. The tweezers was formed by a tapered four-mode fiber (FMF) with the diameter of 8 µm, causing the resonance field of the high-order mode extension to the ambient for manipulating the micro-objects. The diameter of the FMF taper was much larger than that of previous nano-fiber device, making it work as a sturdy tweezers. At the wavelengths ranging from 1500 nm to 1600 nm, especially close to 1560 nm, the E. coli trapping and delivering along the fiber were observed apparently. The method of higher-order micro-fiber modes offers a new opportunity for better using optical manipulation at the single-cell level.