[Paper Review] Controllable light capsules employing modified Bessel-Gauss beams

Lei Gong, Weiwei Liu+5 more|arXiv (Cornell University)|May 11, 2016

Orbital Angular Momentum in Optics53 references3 citations

TL;DR

This paper proposes a novel method to generate controllable three-dimensional light capsules—optical bottles with near-perfect darkness—using modified Bessel-Gauss beams. By tuning beam parameters and employing a binary digital micromirror device (DMD) for precise amplitude and phase control, the authors demonstrate tunable bottle geometries capable of optically trapping core-shell magnetic microparticles, enabling new possibilities in micromanipulation of absorbing particles and aerosols.

ABSTRACT

We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms.

Motivation & Objective

• To develop a new class of controllable three-dimensional light capsules with high darkness and tunable geometry.
• To leverage intrinsic properties of modified Bessel-Gauss beams to naturally form optical bottles during propagation.
• To enable precise control over the shape and size of optical traps through beam parameter tuning.
• To demonstrate optical trapping of core-shell magnetic microparticles using holographic tweezers based on these beams.
• To provide a scalable, reconfigurable method for generating and manipulating optical bottles using DMD-based beam shaping.

Proposed method

• Utilization of modified Bessel-Gauss beams to generate self-healing, non-diffracting beams with a central intensity null.
• Parameter optimization of beam order, radial mode, and beam width to control the size and shape of the optical bottle.
• Employment of a binary digital micromirror device (DMD) for precise amplitude and phase modulation to shape the beam into a desired bottle profile.
• Implementation of holographic optical tweezers using the shaped beam to trap and manipulate microparticles.
• Theoretical modeling of the beam's intensity and phase distribution to predict the formation of the three-dimensional dark region.
• Experimental validation of the optical bottle formation and particle trapping under various beam configurations.

Experimental results

Research questions

• RQ1 Can modified Bessel-Gauss beams naturally form three-dimensional optical bottles with high darkness during propagation?
• RQ2 To what extent can the geometry of the optical bottle be tuned by adjusting beam parameters?
• RQ3 How effectively can a DMD-based system shape and control the beam to generate desired bottle profiles?
• RQ4 Can the generated optical bottles stably trap core-shell magnetic microparticles for micromanipulation?
• RQ5 What are the limits and capabilities of this method for trapping absorbing particles and aerosols?

Key findings

• The modified Bessel-Gauss beam forms a three-dimensional optical bottle with a central dark region due to its inherent intensity null and self-healing properties.
• The size and shape of the optical bottle can be dynamically controlled by tuning beam parameters such as order and radial mode.
• The DMD-based beam shaping technique enables precise amplitude and phase control, allowing reliable generation of complex bottle geometries.
• Optical trapping experiments successfully demonstrated stable confinement of core-shell magnetic microparticles within the dark region of the bottle.
• The method enables reconfigurable, non-diffracting optical traps suitable for manipulating absorbing particles, aerosols, and potentially individual atoms.
• Theoretical and experimental results confirm the formation of a nearly perfect dark region, essential for minimizing photodamage during trapping.