Design of a wavelength-tunable optical tweezer using a graded-index multimode optical fiber

TL;DR

This paper presents a wavelength-tunable optical fiber tweezer using a flat-endface graded-index multimode fiber, enabling remote trapping position control over a long range with simpler fabrication compared to tapered designs.

Contribution

It introduces a novel flat-endface GIMF-based optical tweezer with wavelength-dependent trapping positions, simplifying fabrication and extending trapping range.

Findings

Supports trapping positions far from fiber tip

Wavelength tuning adjusts trapping position over a long range

Simpler fabrication process than tapered-endface OFTs

Abstract

A wavelength-tunable Optical Fiber Tweezer (OFT) based on a Graded Index Multimode Fiber (GIMF) with a flat endface is proposed. It is shown that the design can support a trapping position which is far from the tip of the GIMF compared with other common optical tweezing methods, hence reducing the possibility of a contact between the trapped particle and the fiber tip. Moreover, because of the wavelength dependence of the GIMF design parameters such the Numerical Aperture (NA), the trapping position can become wavelength-dependent. Therefore, the trapping position can be tuned over a long range using a common wave-length tunable laser. The proposed OFT differs from previous fiber-based demonstrations by using a flat-endface fiber making the fabrication and experiment quite easier than previously proposed tapered-endface OFTs.