Absorbing particle 3D trap based on annular core fiber tweezers

Abstract

We proposed and demonstrated a new method to trap and manipulate a strongly absorbing particle by harnessing strong Δα-type photophoretic forces in pure liquid glycerol with a focused annular beam, which was introduced by an annular core fiber optical tweezers. We performed the focused annular light field by integrating a high refractive index silica microsphere on the annular core fiber end facet. The silica microsphere, which acted as a lens, focused laser beam for trapping. We tested and calculated Δα-type photophoretic forces tendency by using the fluorescence dye method, and the simulated results were in agreement with the experimental results. The proposed optical fiber tweezers were small in size, large in capture range, simple to manipulate, and inexpensive in cost. It provided a new approach for absorbing particles trapping. Tailoring the trapping and manipulation of absorbing particles in liquid environments will open avenues for studying the special, yet-unexplored characteristics of absorbing particles.