Nonlinear generation of Airy vortex beam

Author(s):
Hui Li and Haigang Liu and Xianfeng Chen

Abstract:

“Recently, hybrid beams have sparked considerable interest because of their properties coming from different kinds of beams at the same time. Here, we experimentally demonstrate Airy vortex beam generation in the nonlinear frequency conversion process when the fundamental wave with its phase modulated by a spatial light modulator is incident into a homogeneous nonlinear medium. In our experiments, second harmonic Airy circle vortex beams and Airy ellipse vortex beams were generated and the topological charge was also measured. The parabolic trajectory of those Airy vortex beams can be easily adjusted by altering the fundamental wave phase. This study provides a simple way to generate second harmonic Airy vortex beams, which may broaden its future use in optical manipulation and light-sheet microscopy.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express Volume 26, Issue 16
DOI: 10.1364/oe.26.021204

Multiple-plane image formation by Walsh zone plates

Author(s):

Federico Machado, Vicente Ferrando, Fernando Giménez, Walter D. Furlan, and Juan A. Monsoriu

Abstract:

“A radial Walsh filter is a phase binary diffractive optical element characterized by a set of concentric rings that take the phase values 0 or π, corresponding to the values + 1 or −1 of a given radial Walsh function. Therefore, a Walsh filter can be re-interpreted as an aperiodic multifocal zone plate, capable to produce images of multiple planes simultaneously in a single output plane of an image forming system. In this paper, we experimentally demonstrate for the first time the focusing capabilities of these structures. Additionally, we report the first achievement of images of multiple-plane objects in a single image plane with these aperiodic diffractive lenses.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express Volume 26, Issue 16
DOI: 10.1364/OE.26.021210

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

Wide-field in situ multiplexed Raman imaging with superresolution

Author(s):

Houkai Chen and Xiaojing Wu and Yuquan Zhang and Yong Yang and Changjun Min and Siwei Zhu and Xiaocong Yuan and Qiaoliang Bao and Jing Bu

Abstract:

“Because of the fingerprint-like specificity of its characteristic spectrogram, Raman spectral imaging has been applied widely in various research areas. Using a combination of structured illumination with the surfaceenhanced Raman scattering (SERS) technique, wide-field Raman imaging is developed with a significant improvement in spatial resolution. As a result of the relatively narrow Raman characteristic peaks, optically encoded SERS nanoparticles can be used to perform multiplexed imaging. The results show excellent superresolution wide-field multiplexed imaging performance. The developed technique has extraordinary potential for applications in biological imaging and other related fields.”

Link to Publications Page

Publication: Photonics Research
Issue/Year/DOI: Photonics Research Volume 6, Issue 6 pp. 530-534
DOI: 10.1364/PRJ.6.000530

Micro-Dumbbells—A Versatile Tool for Optical Tweezers

Author(s):

Weronika Lamperska, Sławomir Drobczyński, Michał Nawrot, Piotr Wasylczyk, Jan Masajada

Abstract:

“Manipulation of micro- and nano-sized objects with optical tweezers is a well-established, albeit still evolving technique. While many objects can be trapped directly with focused laser beam(s), for some applications indirect manipulation with tweezers-operated tools is preferred. We introduce a simple, versatile micro-tool operated with holographic optical tweezers. The 40 µm long dumbbell-shaped tool, fabricated with two-photon laser 3D photolithography has two beads for efficient optical trapping and a probing spike on one end. We demonstrate fluids viscosity measurements and vibration detection as examples of possible applications.”

Link to Publications Page

Publication: Micromachines

Issue/Year/DOI: Micromachines Volume 9, Issue 6
DOI: 10.3390/mi9060277

Particle trapping and conveying using an optical Archimedes’ screw

Author(s):

Barak Hadad and Sahar Froim and Harel Nagar and Tamir Admon and Yaniv Eliezer and Yael Roichman and Alon Bahabad

Abstract:

“Trapping and manipulation of particles using laser beams has become an important tool in diverse fields of research. In recent years, particular interest has been devoted to the problem of conveying optically trapped particles over extended distances either downstream or upstream of the direction of photon momentum flow. Here, we propose and experimentally demonstrate an optical analog of the famous Archimedes’ screw where the rotation of a helical-intensity beam is transferred to the axial motion of optically trapped micrometer-scale, airborne, carbon-based particles. With this optical screw, particles were easily conveyed with controlled velocity and direction, upstream or downstream of the optical flow, over a distance of half a centimeter. Our results offer a very simple optical conveyor that could be adapted to a wide range of optical trapping scenarios.”

Link to Publications Page

Publication: Optica

Issue/Year/DOI: Optica Vol. 5, Issue 5, pp. 551-556 (2018)

DOI: 10.1364/OPTICA.5.000551

 

Experimental demonstration of tunable refractometer based on orbital angular momentum of longitudinally structured light

Author(s):

Dorrah, Ahmed H and Zamboni-Rached, Michel and Mojahedi, Mo

Abstract:

“The index of refraction plays a decisive role in the design and classification of optical materials and devices; therefore, its proper and accurate determination is essential. In most refractive index (RI) sensing schemes, however, there is a trade-off between providing high-resolution measurements and covering a wide range of RIs. We propose and experimentally demonstrate a novel mechanism for sensing the index of refraction of a medium by utilizing the orbital angular momentum (OAM) of structured light. Using a superposition of co-propagating monochromatic higher order Bessel beams with equally spaced longitudinal wavenumbers, in a comb-like setting, we generate nondiffracting rotating light structures in which the orientation of the beam’s intensity profile is sensitive to the RI of the medium (here, a fluid). In principle, the sensitivity of this scheme can exceed ∼ 2700°/RIU with a resolution of ∼ 10-5 RI unit (RIU). Furthermore, we show how the unbounded degrees of freedom associated with OAM can be deployed to offer a wide
dynamic range by generating structured light that evolves into different patterns based on the change in RI. The rotating light structures are generated by a programmable spatial light modulator (SLM). This provides dynamic control over the sensitivity, which
can be tuned to perform coarse or fine measurements of the RI in real time. This, in turn, allows high sensitivity and resolution to be achieved simultaneously over a very wide dynamic range, which is a typical trade-off in all RI sensing schemes. We thus envision that this method will open new directions in refractometry and remote sensing.”

Link to Publications Page

Publication: Light: Science \& Applications

Issue/Year/DOI: Light: Science & Applications accepted article preview 18 May 2018
DOI: 10.1038/s41377-018-0034-9

Three-dimensional vectorial multifocal arrays created by pseudo-period encoding

Author(s):

Tingting Zeng and Chenliang Chang and Zhaozhong Chen and Hui-Tian Wang and Jianping Ding

Abstract:

“Multifocal arrays have been attracting considerable attention recently owing to their potential
applications in parallel optical tweezers, parallel single-molecule orientation determination,
parallel recording and multifocal multiphoton microscopy. However, the generation of vectorial
multifocal arrays with a tailorable structure and polarization state remains a great challenge, and
reports on multifocal arrays have hitherto been restricted either to scalar focal spots without
polarization versatility or to regular arrays with fixed spacing. In this work, we propose a specific
pseudo-period encoding technique to create three-dimensional (3D) vectorial multifocal arrays
with the ability to manipulate the position, polarization state and intensity of each focal spot. We
experimentally validated the flexibility of our approach in the generation of 3D vectorial multiple
spots with polarization multiplicity and position tunability.”

Link to Publications Page

Publication: Journal of Optics

Issue/Year/DOI: Journal of Optics, Volume 20, Number 6
DOI: 10.1088/2040-8986/aac1de