Generation of reconfigurable optical traps for microparticles spatial manipulation through dynamic split lens inspired light structures

Author(s):

Angel Lizana and Haolin Zhang and Alex Turpin and Albert Van Eeckhout and Fabian A. Torres-Ruiz and Asticio Vargas and Claudio Ramirez and Francesc Pi and Juan Campos

Abstract:

“We present an experimental method, based on the use of dynamic split-lens configurations, useful for the trapping and spatial control of microparticles through the photophoretic force. In particular, the concept of split-lens configurations is exploited to experimentally create customized and reconfigurable three-dimensional light structures, in which carbon coated glass microspheres, with sizes in a range of 63–75 μm, can be captured. The generation of light spatial structures is performed by properly addressing phase distributions corresponding to different split-lens configurations onto a spatial light modulator (SLM). The use of an SLM allows a dynamic variation of the light structures geometry just by modifying few control parameters of easy physical interpretation. We provide some examples in video format of particle trapping processes. What is more, we also perform further spatial manipulation, by controlling the spatial position of the particles in the axial direction, demonstrating the generation of reconfigurable three-dimensional photophoretic traps for microscopic manipulation of absorbing
particles.”

Link to Publications Page

Publication: Scientific Reports

Issue/Year/DOI: Scientific Reports volume 8, Article number: 11263 (2018)
DOI: 10.1038/s41598-018-29540-1

Shaping the on-axis intensity profile of generalized Bessel beams by iterative optimization methods

Author(s):

Runze Li and Xianghua Yu and Tong Peng and Yanlong Yang and Baoli Yao and Chunmin Zhang and Tong Ye
Abstract:

“The Bessel beam belongs to a typical class of non-diffractive optical fields that are characterized
by their invariant transverse profiles with the beam propagation. The extended and uniformed
intensity profile in the axial direction is of great interest in many applications. However, ideal
Bessel beams only rigorously exist in theory; the Bessel beams generated in the experiment are
always quasi-Bessel beams with finite focal extensions and varying intensity profiles along the
propagation axis. The ability to shape the on-axis intensity profile to meet specific needs is
essential for many applications. Here, we demonstrate an iterative optimization based approach
to engineer the on-axis intensity of Bessel beams through design and fine-tune processes.
Starting with a standard axicon phase mask, the design process uses the computed on-axis beam
profile as a feedback in the iterative optimization process, which searches for the optimal radial
phase distribution that can generate a so-called generalized Bessel beam with the desired on-axis
intensity profile. The fine-tune process repeats the optimization processing by using the adjusted
target on-axis profile according to the measured one. Our proposed method has been
demonstrated in engineering several quasi-Bessel beams with customized on-axis profiles. The
high accuracy and high energy throughput merit its use in many applications. This method is also
suitable to engineer higher-order Bessel beams by adding appropriate vortex phases into the
designed phase mask.”

Link to Publications Page

Publication: Journal of Optics

Issue/Year/DOI: Journal of Optics, Volume 20, Number 8 (2018)

DOI: 10.1088/2040-8986/aace46

On-Chip Detection of Orbital Angular Momentum Beam by Plasmonic Nanogratings

Author(s):

Ji Chen and Xi Chen and Tao Li and Shining Zhu

Abstract:

“Thanks to the unlimited orthogonal states, the orbital angular momentum (OAM) light is widely accepted as a promising carrier for high information multiplexing in optical communications, in which the OAM detection is an important issue. To keep up with the ever‐growing demand for compact integration, here, a plasmonic grating is employed to spatially couple the OAM modes into two separated propagating surface plasmon polariton (SPP) beams with different splitting angles. These splitting angles are found to strongly rely on the topological charges of the incident beams and are insensitive to the specific location of the OAM beam illumination, which provides an intuitive detection of the OAM modes without particular alignment. Besides, a further unidirectional SPP launching from the OAM beam is also achieved by a particular composite grating. With such composite grating, both the topological charge value and sign of OAM beam in a single measurement can be detected. Our results provide a convenient method for alignment‐free OAM detection by a compact device, and would inspire more multiplexing applications in nanophotonics.”

Link to Publications Page

Publication: Laser & Photonics Reviews

Issue/Year/DOI: Laser & Photonics Reviews Volume 12, Issue 8 (2018)

DOI: 10.1002/lpor.201700331