All-silica fiber Bessel-like beam generator and its applications in longitudinal optical trapping and transport of multiple dielectric particles

Abstract

A Bessel-like beam was generated in a novel all-fiber integrated structure. A concentric ring intensity pattern was achieved by the multimode interference along the coreless silica fiber, which was then focused by the integrated micro-lens to result in a Bessel-like beam. The average beam diameter of 7.5 μm maintained over 500 μm axial length for a continuous wave Yb-doped fiber laser input oscillating at the wavelength of 1.08 μm. The generated beam was successfully applied to two-dimension optical trapping and longitudinal transport of multiple dielectric particles confirming its unique non-diffracting and self-reconstructing nature. Physical principle of operation, fabrication, and experimental results are discussed.

Fourier optics along a hybrid optical fiber for Bessel-like beam generation and its applications in multiple-particle trapping

“…Because of the bulk-optic nature of these prior techniques, a viable solution for microscopic environment has not been provided yet, especially for in situ, in vivo, and in vitro applications. Fiber optic alternatives have been recently attempted using a large-aperture multiple core fiber [4] and a conically lensed fiber [5] for a Gaussian-like beam along with a hollow optical fiber (HOF) [6] and multimode interference (MMI) [7] for Bessel-like beam. In Kim et al's preliminary Bessel-like beam report in [6], the operating wavelength was at 1550 nm where the intrinsic water absorption dominates.…”

“…This resulted in a short propagation distance for a Bessel-like beam in water, and multiple-particle trapping was not achieved. In the MMI configuration [7], the diameter of the central beam was larger, and multiple-particle trapping was achieved only at a substantially higher optical power, which is detrimental to living-cell handling.…”

Self-accelerating Bessel-like beam generated by graded-index multimode fiber

“…The construction of the beam which has both properties of non-diffracting and self-accelerating inspires many researchers' interest: Kaminer [5] finds the non-diffracting beam which can accelerate along the circular orbit at a large angle; Aleahmad [6] finds the Helmholtz beam which can propagate along the oval or sphere orbit; besides that, a few recent works propose techniques to create Bessel-like beams with spiraling or some special trajectories [7][8][9][10][11][12][13]. However, most experimental setups now are based on the bulk optical elements, extremely precise alignment in the free space or optical Fourier transform [14].…”

Objective-free optical-resolution photoacoustic microscopy

“…The all-fiber Bessel beam generation has been achieved by concatenating single mode fiber (SMF), coreless silica fiber (CSF), and a fiberized lens in a compact form. 11,12 Utilizing this all-fiber beaming device, we could get rid of optical objective and associated bulk optics/mechanical components for PA excitation to significantly simplify the system configuration. We have successfully imaged carbon fibers with a diameter of ∼6 μm, and the quantified lateral resolution of better than 6 to 7 μm was achieved in the proposed system.…”

“…CSF is drawn from a pure fused silica rod, and its refractive index is identical to the clad of the SMF and it plays an important role to induce a multimode interference (MMI) pattern. 12 With the optimal curvature of the fiberized lens, the output beam formed by MMI can have a nondiffraction property along the axial direction. Figure 1(b) and 1(c) shows the axial and transverse views of Bessel beam propagation, respectively.…”