JOIN THE IN-PERSON EVENT IN SAN DIEGO, CALIFORNIA
1 - 5 August 2021
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Conference 11818

# Laser Beam Shaping XXI

In person: 1 - 5 August 2021 • 8:00 AM - 5:00 PM PDT
On demand starting 1 August 2021
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• Vortex Beams and OAM
• Polarization and Quantum Optics
• High-Power Beam Shaping
• Materials Processing
• Spatial and Temporal Shaping
• Poster Session
Vortex Beams and OAM
11818-1
Author(s): Yijie Shen, Univ. of Southampton (United Kingdom)
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Structured light, with ability to arbitrarily tailor degrees of freedom (DoFs) of light, amplitude, phase, wavelength, etc, has recently attracted great promotion for fundamental science and advanced applications. In addition to the basic DoFs in light, there are also some complex DoFs emerged as the combination of common DoFs, such as angular momentum, vector singularity, ray-wave trajectory, spatiotemporal vortex, etc., showing their power in optical manipulation. In this talk, I summarize the advanced methods of manipulating tunable DoFs, creating new DoFs and classically entangled states in structured light, as a roadmap guiding the development of multi-dimensional structured light. I also discuss the significance of the multi-DoF control in both fundamental physics and novel applications.
11818-2
Author(s): Kunpeng Liu, Zhigang Liu, Xi'an Jiaotong Univ. (China)
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The vortex lattice and linear vortex array are a network structure of multiple isolated vortices. We propose a method to generate these multi-vortex fields via superimposing two engineered edge dislocation arrays. By designing the topology of the edge dislocation array for stacking, we may obtain an arbitrary-order vortex lattice and linear vortex array. Besides, these edge dislocation array fields can be decomposed into a finite sum of harmonics, which indicates that any-order vortex array can be created by using wave interference. It supplements the research about the vortex array generated by the interference method for the highest-order vortex lattice obtained by interferometry is 3rd at present. The feasibility of the proposed method is validated through simulations and experiments based on fourth-and fifth-order vortex lattices and sixth-and seventh-order linear vortex arrays.
11818-3
Author(s): Nicolas Perez, California State Univ., Northridge (United States), Beckman Laser Institute and Medical Clinic (United States); Daryl Preece, Beckman Laser Institute and Medical Clinic (United States); Anna Bezryadina, California State Univ., Northridge (United States)
On demand starting 1 August 2021
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The conservation of optical properties as a beam propagates through a scattering media is important to creating more complex optically induced structures and the transmission of high bandwidth information. By utilizing the nonlinear optical effect in the scattering bio-soft-matter, we investigate the conservation of polarization and orbital angular momentum through self-trapping and pump/probe coupled waveguides of light in sheep red blood cell suspensions at 532 nm and 780nm wavelengths. The ability to maintain these properties after multiple scattering events may lead to improvements in communication bandwidth with low loss.
11818-4
Author(s): Erick Ramón Baca Montero, Oleksiy V. Shulika, Univ. de Guanajuato (Mexico)
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There exists variety of methods and platforms for the generation of OAM beams. However, all these techniques imply that beams pass through an optical component and thus, when pulsed beam is used, the pulses can acquire dispersive broadening and distortion. The design of compact and efficient devices for OAM generation requires these effects be characterized and quantified, and a set of parameters and techniques for their treatment should be developed. Here, the spatio-temporal properties of the ultrashort vortical pulses are analyzed numerically. Case studies based on several typical laser wavelengths available on the market will be presented with emphasis on reflective spiral phase plate proposed recently by the authors. The results obtained are characterization of the effects of dispersion, geometry and discretization in the numerical modeling of ultrashort vortical pulses under various propagation conditions and can serve as a basis for design of new optical devices.
11818-5
Author(s): Juan A. Fernandez-de la Garza, Benjamin Perez-Garcia, Raul I. Hernandez-Aranda, Tecnológico de Monterrey (Mexico)
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Modal decomposition of a partially coherent Ince-Gaussian beam In this work, we present a strategy for the modal decomposition of a partially coherent Ince-Gaussian (IG) beam. It is shown that the beam can be represented as a suitable superposition of spatially coherent modes. As soon as the beam's spatial coherence decreases, its modal content reveals the existence of transverse coherent higher order modes, with the same ellipticity. We study the dependence of the modal decomposition in terms of the ellipticity and transverse coherence length.
Polarization and Quantum Optics
11818-6
Author(s): Emilio Pisanty, Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (Germany)
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The fundamental polarization singularities of light are generally symmetric under coordinated rotations: that is, transformations which rotate the spatial dependence of the fields by an angle $\theta$ and the field polarization by a fraction $\gamma\theta$ of that angle, as generated by 'mixed' angular momenta of the form $L + \gamma S$. Generically, the coordination parameter $\gamma$ has been thought to be restricted to integer or half-integer values. I will show that this constraint is an artifact of the restriction to monochromatic fields, and that a wider variety of optical singularities is available when more than one frequency is involved.
11818-7
Author(s): Markus Hiekkamäki, Robert Fickler, Tampere Univ. (Finland)
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Structured photons often serve as physical realizations of high-dimensional quantum states beneficial to quantum information. One popular way of discretizing the space is through Laguerre-Gaussian modes that can have twisted phase front and, thus, orbital angular momentum (OAM). We demonstrate that using multi-plane light-conversion techniques enables the performance of complex unitary transformations between multiple input-modes and output-modes in the quantum regime. We demonstrate various complex two-photon interferences observed in spatial modes, thereby realizing a linear optical network along a single beam path. Finally, we show that using this ability allows the generation of spatial-mode NOON-states, which offer angular super-sensitivity.
11818-8
Author(s): Zhensong Wan, Zhaoyang Wang, Tsinghua Univ. (China); Yijie Shen, Univ. of Southampton (United Kingdom); Xing Fu, Tsinghua Univ. (China)
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Our work offers a new way for digitally tailoring ray-wave geometric beam on-demand by replacing the prior mechanical control, which breaks the conventional limitation of a cavity. Furthermore, we validate the digital parallel identification method of higher-order ray-wave geometric modes. On this basis, we experimentally obtain the 16 bits coherent states shift keying through 16-fold multiplexed ray-wave modes in free-space, which verifies the potential of ray-wave geometric beams for optical communication. Our work provides new possibilities for quantum-to-classical applications of ray-wave geometric modes.
11818-9
Author(s): Mateusz Szatkowski, Jan Masajada, Wroclaw Univ. of Science and Technology (Poland); Dorilian Lopez-Mago, Tecnológico de Monterrey (Mexico)
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This study is a continuation of efforts to implement optical vortices into a steady communication system. This is done through a quantum-mimetic controlled-SWAP gate. One of its roles is high-frequency signals comparison without revealing their content. Each signal is encoded into a separate Orbital Angular Momentum channel through Digital Micromirror Device. This study aims to explore the possibilities of increasing the capacity of such a simultaneous message-passing protocol. It can be done by involving more OAM channels and produce a more complex superposition or exchanging bits into multilevel digits within the current protocol. Both of these possibilities, together with associated challenges and limitations are examined.
High-Power Beam Shaping
11818-10
Author(s): Justin Harrison, Council for Scientific and Industrial Research (South Africa), Univ. of the Witwatersrand (South Africa)
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Flat-top beams are readily employed in laser materials processing owing to their uniform temperature distribution. These beams, however, are not eigenmodes of the free space wave equation and only approximations of flat-top beams can be created. This results in the desired beam only present at a fixed plane which evolves to a non-flat beam beyond that plane. Here we employ a Mach Zehnder interferometer to select a propagation invariant vector flat-top beam. We investigate the amplification of this beam through a dual-stage amplifier and demonstrate and improved amplification of over 5 – 10% as compared to its constituent components.
11818-11
Author(s): Justin Harrison, Council for Scientific and Industrial Research (South Africa), Univ. of the Witwatersrand (South Africa)
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The amplification of low power beams through Master Oscillator Power Amplifier (MOPA) systems are increasingly attractive for efficient power scaling and stable beam performance. The vast majority of models exploring end-pumped power amplifiers have reduced the crystal architectures and in turn the thermally induced lens to a two-dimensional problem which only holds for the small-signal gain region. Here we employ three-dimensional crystal architectures through a piece-wise approach and verify our theoretical approach experimentally in the amplification of Gaussian beams. We demonstrate that our approach holds over both signal gain regions with over 95% correlation.
Materials Processing
11818-12
Author(s): Ralf Jedamzik, Antoine Carre, Volker Hagemann, Lothar Bartelmess, Uwe Petzold, SCHOTT AG (Germany)
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Blue laser light has unique capabilities for material processing of copper gold or aluminium. The energy absorption efficiency at 450 nm in gold is orders of magnitude higher than the absorption at typical infrared wavelengths. Modern blue laser diodes enable very high energy densities. For focusing the laser beam usually fused silica optics are used. Fused silica is known for the very high solarization stability over wide range wavelengths but optical designs are limited to its specific optical position. It would be beneficial for the optical design in terms of performance and flexibility to use optical glass for such applications. Only limited data is available on the solarization behavior of optical glass for high power laser radiation at 450 nm. This paper discusses the requirements on optical materials used for blue laser processing applications regarding long time stability aspects, showing recent results in the development of solarization stable glass optical glasses.
11818-13
Author(s): Akinori Ohkubo, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
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In the laser stealth dicing system, focusing pulsed laser forms a modification layer and cracks inside a silicon wafer through scanning. During pulsed laser irradiations, there are interferences between existing cracks and a focusing laser beam on a defocus plane. As a result, a part of interacted laser beam scatters, generating back-side splash defects on the device layer. Therefore, defocused laser beam shaping is necessary to suppress back-side splash defects. At the same time, the focused spot should maintain sufficiently small focused spot size to generate a modified layer inside the silicon wafer. This paper presents innovative focus spot shaping with an asymmetrical pupil phase filter which is optimized for both defocused and focused spot individually. The optimized phase filter generates a highly three-dimensional and asymmetrical focusing spot to realize sufficiently small focused spot and asymmetrical shaped defocused spot simultaneously.
11818-14
Author(s): Paul Lebow, U.S. Naval Research Lab. (United States), Alaire Technologies, Inc. (United States); James R. Lindle, U.S. Naval Research Lab. (United States), DCS Corp. (United States); Abbie T. Watnik, U.S. Naval Research Lab. (United States)
On demand starting 1 August 2021
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Optical phase conjugation using computer generated holograms takes advantage of the ability to tailor a wavefront for specific applications. We are investigating techniques to tile multiple SLM’s to provide increased resolution using existing devices. For a multiple SLM arrangement, quick techniques to compensate for these are critical since slight mechanical micron-level variations can impact relative phase between SLM’s. Our approach uses a simple algorithm to measure the cumulative phase error introduced by the SLM, system optics and geometry and then subtracts that error from any ideal pattern imposed on the SLM. We will present results showing the effectiveness of this technique.
11818-15
Author(s): Ilya V. Galaktionov, Alexander Nikitin, Julia Sheldakova, Inst. of Geosphere Dynamics (Russian Federation); Alexis Kudryashov, Moscow Polytech (Russian Federation), Inst. of Geosphere Dynamics RAS (Russian Federation)
On demand starting 1 August 2021
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Conventional Shack-Hartmann sensor uses Zernike polynomials in order to approximate the wavefront of the light. Zernike approximation is well-known, well-established and widely used technique. And in most cases the quality of approximation is good enough, especially if the measured light beam has circular aperture. But when the light beam is rectangular or ring-shaped (for example, if one need to measure the surface flatness of the detail that is ring-shaped), the approximation using Zernike polynomials fails. In this work we implemented the approach of the approximation of the wavefront using B-spline polynomials. We demonstrate that this approach works well for any type of the light beam aperture. We present the results of approximation of the simple wavefronts (defocus, coma, etc.) and complex wavefronts (Franke surface, surface with 2 local bumps, etc.) in circular, ring and arbitrary apertures using Zernike- and B-Spline polynomials.
11818-16
Author(s): Daniel Urrego, Gerard J. Machado, ICFO - Institut de Ciències Fotòniques (Spain); Juan P. Torres, ICFO - Institut de Ciències Fotòniques (Spain), Univ. Politècnica de Catalunya (Spain)
On demand starting 1 August 2021
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Optical Coherence Tomography (OCT) is an imaging technique that performs high-resolution transverse and axial imaging of samples. We demonstrate a novel mechanical-scan free Spectral Domain OCT scheme that performs axial and transverse scans of the sample avoiding the use of any kind of mechanical platforms. The scheme makes use of a spatial light modulator in combination with some simple optical elements. This proof-of-principle demonstration can help usher in the development of alternative OCT schemes with potentially faster scan speeds than current OCT schemes by avoiding the use of any kind of mechanical platforms.
Spatial and Temporal Shaping
11818-17
Author(s): Jose Rebolledo-Lopez, Dorilian Lopez-Mago, Servando Lopez-Aguayo, Tecnológico de Monterrey (Mexico)
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Wave branching occurs during propagation in a gently disordered medium. It appears in many different physical situations involving diverse length scales: from electron waves refracted in semiconductors to ocean waves deflected by surface eddies. Very recently, this phenomenon has been observed in light by studying the propagation of laser beams in soap films, opening an exciting field of research where the entire machinery of structured light can be brought to bear. Here, we develop computational tools to simulate and characterize the branched flow of light propagating through two-dimensional inhomogeneous media. We present the effects of varying the correlation length of the scattering medium, the influence of shaping the input beam, and the statistical features depicting the branching of light.
11818-18
Author(s): Manuel F. Ferrer-Garcia, Alessio D'Errico, Alicia Sit, Ebrahim Karimi, Univ. of Ottawa (Canada)
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11818-19
Author(s): Lusine M. Tsarukyan, Anahit Badalyan, Rafael Drampyan, Institute for Physical Research, NAS RA (Armenia)
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We report the experimental results of a soliton-like optical beam formation in a photorefractive Fe doped lithium niobate (LN:Fe) crystal caused by a pyroelectric effect. The laser beam at 632.8 nm wavelength with powers of 0.5-10 mW and a 10 mm length LN:Fe crystal with the controlled temperature in the range of 10-45 C are used. The time evolution of the soliton formation shows approximately two times decrease of the optical beam diameter to ~60 um with simultaneous bending of ~120 um opposite to the crystalline C+-axis. The generated curvilinear waveguiding channels in the crystal are long-living making them promising for applications.
11818-20
Author(s): Zhaoyang Wang, Tsinghua Univ. (China); Yijie Shen, Univ. of Southampton (United Kingdom); Zhensong Wan, Qiang Liu, Xing Fu, Tsinghua Univ. (China)
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We propose a new theory to unify the TW and SW formations of structured light, generalizing the family of ray-wave geometric beams based on TW-SW unified eigenmodes (IG, HLG, and HIG modes) and extending new topological ray-wave structures as their complex coherent states. Our theoretical framework has strong extensibility to construct more complex modes such as generalizing ray-wave Lissajous-trochoidal wave packets and unifying the TW-SW formations of non-diffracting and self-healing eigenmodes (Bessel, Mathieu, Airy modes) in various orthogonal coordinates, inspiring the exploration for more topological properties of novel structured light with advanced applications.
11818-21
Author(s): Cristian Hernando Acevedo Cáceres, Yezid Torres Moreno, Univ. Industrial de Santander (Colombia); Aristide Dogariu, CREOL, The College of Optics and Photonics, Univ. of Central Florida (United States)
On demand starting 1 August 2021
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Non-diffracting beams and in particular the Mathieu beams are useful in applications related with photonic lattices and particle trapping. These beams are solution of Helmholtz equation in elliptical coordinates. Recent works has demostrated remarkable properties of the intensity correlation in speckle pattern generated using non-diffracting beam with cylindrical symmetry such the Bessel beams. In these work we present a theoretical study of the speckle pattern generated by scattering of Mathieu beams through a diffuser. We demostrated theoretically and numerically that in free-space propagation the speckle pattern evolves with propagation distance, while in the Fourier regime the speckle pattern does not evolve with the longitudinal distance.
Poster Session
11818-22
Author(s): Ilya V. Galaktionov, Vladimir Toporovsky, Julia Sheldakova, Institute of Geosphere Dynamics, RAS (Russian Federation); Alexis V. Kudryashov, Moscow Polytechnic Univ. (Russian Federation)
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Bimorph deformable mirrors can be successively used to improve focusing of a laser beam passed through a moderately scattering medium with optical density in the range of 1 ... 10. In this paper we investigate the efficiency of the stacked actuator deformable mirror with 61 piezo stacks and clear aperture of 60 mm. We demonstrate that such kind of mirrors also can be used to optimize the focal spot in the far-field. Shack-Hartmann sensor was used to measure the averaged wavefront distortions and CCD camera was used to estimate the intensity distribution of the focal spot in the far-field.
Conference Chair
Univ. of the Witwatersrand, Johannesburg (South Africa)
Conference Chair
Program Committee
FMD Consulting LLC (United States)
Program Committee
Univ. of the Witwatersrand, Johannesburg (South Africa)
Program Committee
Fraunhofer-Institut für Lasertechnik ILT (Germany)
Program Committee
Tecnológico de Monterrey (Mexico)
Program Committee
Active Optics Night N Ltd. (Russian Federation)
Program Committee
BOLD Laser Automation (United States)
Program Committee
Tecnológico de Monterrey (Mexico)
Program Committee
Beckman Laser Institute and Medical Clinic (United States)
Program Committee
Ctr. for Physical Sciences and Technology (Lithuania)
Program Committee
Centro de Investigaciones en Óptica, A.C. (Mexico)
Program Committee
Wroclaw Univ. of Science and Technology (Poland)