Optical lining of dielectric particles by two counter-propagating all-fiber Bessel-like beams

Abstract

Optical lining of multiple dielectric beads was experimentally demonstrated using two counter- propagating Bessel-like beam generated by multimode interference in optical fibers embedded in polydimethylsiloxane (PDMS) channel. All Fiber Bessel-like beam (AFB) generator was composed of a single mode fiber concatenated with a segment of coreless silica fiber of 1600 μm length and a fiberized focusing lens. A Bessel-like beam was achieved by multimode interference along the coreless silica fiber, and it maintained an average center beam diameter of 3.7 μm over an axial length of 300 μm, having a nearly uniform output power within a variation of ±0.11%. AFB generator was designed to be compatible with a continuous wave Yb-doped fiber laser oscillating at the wavelength of 1084nm in order to provide all-fiber solution. A micro-fluidic system of cross-channel was fabricated using PDMS to embed two counter-propagating fiber probes, which provided an accurate beam alignment and stable delivery of sample. One dimensional optical potential well was generated along the counter propagating beams, where samples were trapped, and then self-optical line of them was formed along longitudinal axis. This results from self-reconstruction, which is property of Bessel beam and it was confirmed in not only dielectric particles but also biological sample. This AFB generator paves the way for novel integration of microfluidic system as optical filter or chromatography.