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PURPOSE Cardiac computed tomography has a clear clinical role in the evaluation of coronary artery disease and assessment of coronary artery calcium (CAC) but the use of ionizing radiation limits the clinical use. Beam-shaping "bow-tie" filters determine the radiation dose and the effective scan field-of-view diameter (SFOV) by delivering higher X-ray fluence to a region centered at the isocenter. A method for positioning the heart near the isocenter could enable reduced SFOV imaging and reduce dose in cardiac scans. However, a predictive approach to center the heart, the extent to which heart centering can reduce the SFOV, and the associated dose reductions have not been assessed. The purpose of this study is to build a heart-centered patient positioning model, to test whether it reduces the SFOV required for accurate CAC scoring, and to quantify the associated reduction in radiation dose. METHODS The location of 38,184 calcium lesions (3151 studies) in the Multi-Ethnic Study of Atherosclerosis was utilized to build a predictive heart-centered positioning model and compare the impact of SFOV on CAC scoring accuracy in heart-centered and conventional body-centered scanning. Then, the positioning model was applied retrospectively to an independent, contemporary cohort of 118 individuals (81 with CAC > 0) at our institution to validate the model's ability to maintain CAC accuracy while reducing the SFOV. In these patients, the reduction in dose associated with a reduced SFOV beam-shaping filter was quantified. RESULTS Heart centering reduced the SFOV diameter 25.7% relative to body centering while maintaining high CAC scoring accuracy (0.82% risk reclassification rate). In our validation cohort, imaging at this reduced SFOV with heart-centered positioning and tailored beam-shaping filtration led to a 26.9% median dose reduction (25-75th percentile: 21.6%-29.8%) without any calcium risk reclassification. CONCLUSIONS Heart-centered patient positioning enables a significant radiation dose reduction while maintaining CAC accuracy.

International audience; We demonstrate a silicon (Si)-gallium arsenide (GaAs) semiconductor based holographic metasurface antenna operating at 94 GHz. The metasurface antenna molds the radiated beam by resorting to a holographic approach involving the modulation of a guided-mode generated by a pillbox beam former. The pillbox beam former is fed by three integrated horns in Substrate Integrated Waveguide (SIW) technology located in the focal plane of the parabolic reflector of the pillbox beam former. The three horns correspond to three independent beams and allow beam steering by switching from one feed to another. The proposed metasurface antenna is planar and extremely lowprofile, thus suitable for small platforms such as CubeSats/SmallSats. A prototype validates the concept demonstrating a directivity as high as 31.9 dBi and a reflection coefficient lower than-15 dB at 94 GHz.

Due to their subwavelength thickness, light weight and easy fabrication, metasurfaces show obvious advantages over 3D metamaterials. Among this, a new concept so-called digital coding metasurfaces ...

Interlaced metallic meshes form a class of three-dimensional metamaterials that exhibit nondispersive, broadband modes at low frequencies, without the low frequency cutoff typical of generic wire grid geometries. However, the experimental observation of these modes has remained an open challenge, both due to the difficulties in fabricating such complex structures and also because the broadband mode is longitudinal and does not couple to free-space radiation (dark mode). Here we report the first experimental observation of the low frequency modes in a block of interlaced meshes fabricated through 3D printing. We demonstrate how the addition of monopole antennas to opposing faces of one of the meshes enables coupling of a plane wave to the low frequency "dark mode" and use this to obtain the dispersion of the mode. In addition, we utilize orthogonal antennas on opposite faces to achieve polarization rotation as well as phase shifting of radiation passing through the structure. Our work paves the way toward further experimental study into interlaced meshes and other complex 3D metamaterials.

This article describes a novel optical tweezer system which utilizes a magnetic fluid deformable mirror (MFDM) with a wavefront sensor (WFS) and controller to produce a curved Bessel beam for manipulating an optically trapped microparticle. The MFDM is proposed to control the wavefront phase of the laser beam since it offers the ability to produce a nearly perfect axicon in reflection. The working principle of the MFDM and its modeling and design processes are introduced. A decentralized control method is presented for the MFDM to generate the desired mirror surface shape, combing an axicon and an adjustable compensation phase profile that transforms the incident beam into a self-accelerating Bessel-like beam with curved trajectory. Using a prototype MFDM, an experimental optical tweezer system is set up to verify this optical micromanipulation method. The experimental results show the effectiveness of the proposed technique for the manipulation of optically trapped microparticles.

Collimating lenses are an important component of laser ranging systems, and high overload environments severely affect the beam shaping effect of such lenses. This study proposes a buffer isolation method on the basis of impact stress wave attenuation theory for collimating lens spacers. ANSYS finite element software was applied to simulate the high load dynamics of collimating lenses, and the buffer isolation performance of different materials and composite structures was compared and analysed. Optical simulation analysis of the collimating lenses under different buffer conditions was performed using ZEMAX software to study the mechanism by which a high overload affects the collimating lenses. High overload and optical shaping experiments based on theoretical analysis were further conducted. Results showed the superiority of butadiene rubber to polytetrafluoroethylene after application of 70000 g impact acceleration. The combination-gasket method was superior to the single-gasket method, and the sandwich combination-gasket method was superior to the double-layer combination-gasket method.

A watt-level directly diode-pumped continuous-wave (CW) Ti:Sapphire oscillator was demonstrated for the first breakthrough by a high-power green laser-diode-pumped module employing the technologies of beam shaping, beam collimation, polarization beam combining, and fiber coupling. A 1.36-W output power and 10.6% of slope efficiency were obtained based on the double-concave (DC) cavity configuration. This is the highest CW output power from Ti:Sapphire (Ti:S) oscillator directly pumped by green laser diodes (LDs) reported so far.

Recent developments in laser beam sources expand the possibilities of laser beam welding of similar and dissimilar copper joints. New methods of beam shaping and adjustable intensity profiles using two layer fibers create a center and ring spot, which is the newest state of the art in fiber laser beam sources. In this study, the influences and possibilities of adjustable intensity profiles on the weldability of steel copper dissimilar lap joints with copper on the top side will be discussed. The results show that the former problems of spattering and poor beam coupling in copper can be avoided through new beam shaping technologies and adjusted parameter settings. In the investigations joints without melt ejections on copper surfaces of state of the art fiber laser technologies are demonstrated and the influence of different intensity distributions on the weld geometry will be discussed.

We have analyzed the possibilities of wave front shaping with miniature patterned electron mirrors through the WKB approximation. Based on this, we propose a microscopy scheme that uses two miniature electron mirrors on an auxiliary optical axis that is in parallel with the microscope axis. A design for this microscopy scheme is presented for which the two axes can be spatially separated by as little as 1 mm. We first provide a mathematical relationship between the electric potential and the accumulated phase modulation of the reflected electron wave front using the WKB approximation. Next, we derive the electric field in front of the mirror, as a function of a topographic or pixel wise excited mirror pattern. With this, we can relate the effect of a mirror pattern onto the near-field phase, or far field intensity distribution and use this to provide a first optical insight into the functioning of the patterned mirror. The equations can only be applied numerically, for which we provide a description of the relevant numerical methods. Finally, these methods are applied to find mirror patterns for controlled beam diffraction efficiency, beam mode conversion, and an arbitrary phase and amplitude distribution. The successful realization of the proposed methods would enable arbitrary shaping of the wave front without electron-matter interaction, and hence we coin the term virtual phase plate for this design. The design may also enable the experimental realization of a Mach–Zehnder interferometer for electrons, as well as interaction-free measurements of radiation sensitive specimen.

An approach to generate the tunable fractional vector curvilinear beams (VCBs) was proposed. The scheme is based on the vector optical field generator (VOFG) system, where the two orthogonal polarized scalar curvilinear beams (SCBs) are generated to be the base vector components, and coaxially superposed by a Ronchi grating. We design a new phase distribution with several loops of 0 to π in order to generate more dark gaps. The phase distribution becomes nonuniform by varying the phase variation rate and the positions of the dark gaps are changed. Using the different parameters of the curves, the fractional VCBs with different shapes are achieved. The two orthogonal polarized SCBs with the opposite topological charges are modulated to perform the beam conversion by a phase-only computer-generated hologram (CGH). Our experimental results comply with the theory and the radial opening of the dark gaps may have some applications for guiding and transporting particles.

Efficient beam supercollimation is proposed and shown experimentally by axisymmetric aperiodic photonic structures. The structure consists of equidistant layers of concentric refraction index rings, with the transverse period of the rings varying from layer to layer along the structure. Numerically designed and optimized axisymmetric photonic structures are inscribed in silica glass by femtosecond pulses. Strong enhancement (more than by one order of magnitude) of the axial beam component is demonstrated, resulting in the record performance of the beam supercollimation.

[EN]High-harmonic generation (HHG) is a unique tabletop light source with femtosecond-to-attosecond pulse duration and tailorable polarization and beam shape. Here, we use counter-rotating femtosecond laser pulses of 0.8 µm and 2.0 μm to extend the photon energy range of circularly polarized high-harmonics and also generate single-helicity HHG spectra. By driving HHG in helium, we produce circularly polarized soft x-ray harmonics beyond 170 eV—the highest photon energy of circularly polarized HHG achieved to date. In an Ar medium, dense spectra at photon energies well beyond the Cooper minimum are generated, with regions composed of a single helicity—consistent with the generation of a train of circularly polarized attosecond pulses. Finally, we show theoretically that circularly polarized HHG photon energies can extend beyond the carbon K edge, extending the range of molecular and materials systems that can be accessed using dynamic HHG chiral spectro-microscopies, Department of Energy BES (DE-FG02-99ER14982); Air Force Office of Scientific Research (FA9550-16-1-0121); National Science Foundation (DGE-1144083, DGE-1650115); European Research Council (8511201); Ministerio de Ciencia, Innovación y Universidades (PID2019-106910GB-100); Junta de Castilla y León (SA287P18); Ramón y Cajal contract (RYC-2017-22745).

Unlike the conventional design of aspheric shaping systems, in order to provide a laser source for applications such as multi-beam laser interference, which can maintain evenly distributed power over a large distance, the influence of shape parameter and aperture on long-distance propagation performance of Kepler refractive beam shaping system is studied. Current work describes the lens, designed automatically by using ZEMAX programming language (ZPL), and simulations of Kepler refractive shaping systems of flattened Lorenz (FL) beams with different shape parameters and apertures.

Optical tweezers are an established and extremely useful tool for manipulating microscopic particles with light. Optical tweezers systems regularly include optical components for creating complex structured light fields and detectors for measuring the resulting optical forces. Computational tools are often invaluable for generating and controlling structured light fields, modelling optically trapped particles and analysing experimental measurements.In this thesis I describe several computational tools and methods for modelling and controlling optical tweezers. There is a range of existing methods for simulating optical tweezers but there are relatively few general and easy to use tools. Here I describe two new open source toolboxes: a new version of the Optical Tweezers Toolbox (OTT) and a new beam shaping toolbox, OTSLM Toolbox for Structured Light Methods (OTSLM). These toolboxes enable the production and simulation of diverse structured optical fields. While existing tools tend to focus on particular hardware or demonstrating particular kinds of algorithms, these new toolboxes instead focus on usability and versatility for modelling a wide range of problems.Recently, machine learning has been very successful in modelling complex processes and solving difficult classification problems. Part of this thesis is dedicated to exploring how machine learning could be used to enable faster and more extensive optical tweezers simulations. One of the main problems with conventional methods is achieving sufficient accuracy without excessive runtimes. I demonstrate how machine learning can enable faster optical tweezers simulations and increase the range of tractable problems. Further still, I demonstrate how machine learning is useful for analysing optical tweezers measurements including for rapidly classifying optically trapped particles and improving force measurement accuracy.With these tools we are able to explore how particles scatter light, the dynamics of particles in optical traps, the accuracy of different measurement techniques and much more. Many of these application are demonstrated throughout this thesis and these simulations support, and are supported by, our groups recent experimental work.

Nonlinear multiplexing holography emerges as a powerful tool to produce structured lights at new wavelengths. In this work, we propose and experimentally demonstrate an angle-multiplexing nonlinear holography in an angular noncritical phase-matching configuration. In experiment, various types of structured light beams, such as vortex beam, Airy beam and Airy vortex beam, are simultaneously output at second-harmonic waves along different paths. Because of the large angular acceptance bandwidth of noncritical phase-matching, one can achieve high conversion efficiency of angle-multiplexing nonlinear holography. Our method has potentially applications in high-capacity holographic storage and security encryption.

In this study, we present the simulations and experimental observations of photonic jet (PJ) shaping by control of tangential electric field components at illuminating wavelengths of 405 nm, 532 nm, and 671 nm. The PJs are generated by a single dielectric 4-micrometer cube that was fabricated from polydimethylsiloxane (PDMS). The dielectric cube is deposited on a silicon substrate and placed on two aluminum masks with a width equal to the side length of the cube. Due to the appearance of the metal masks, the focal length and decay length of the generated PJs decreased almost twice, while the PJ resolution increased 1.2 times. Thus, PJ shaping can be controlled by the presence of the metal mask along the lateral surface of the cube without changing the external shape or internal structure of the cube. This effect is based on the control of the tangential components of the electric field along the lateral surface of the cube. In the case of a one-sided metal mask, the effect of optical deflection and bending is predicted to form a photonic hook. Due to the low cost of these dielectric cubes, they have potential in far-field systems to better meet the requirements of modern optical integration circuits and switches.

OLEDs are thin-film devices consisting of multilayers of organic thin films sandwiched between a metal and an ITO electrodes. Because of the different refractive indices of the layers in the thin film stack, different optical modes are trapped in the device. In this talk, we will first discuss the physics of these optical modes and describe techniques to characterize them. We will then describe how to use various photonic structures to maximize the light output and manipulate these optical modes to control the polarization as well as directionality to achieve beam shaping.

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.

We proposed an automatic sorting method based on a virtual optical chip, which was formed by a complex-amplitude beam shaping system. The automatic sorting of different micro-particles was realized by the optical forces of the intensity and phase gradients of the reconstructed optical beam. The method was verified with theoretical analysis and experimental results. Compared with the traditional optical sorting methods, the proposed one does not need high-precision mechanical and/or microfluidic devices. The optical chip is flexible in structure and efficient in optical sorting and can be used in the fields of medical detection and material sensing.

All-dielectric resonant metasurfaces has been emerging as a breakthrough platform for manipulating light, leading to advanced nanophotonic device architectures for lasing, ultrathin optical elements, beam shaping and sensing [1] - [3] . However, the current metasurfaces are often locked to a fixed functionality due to their static constituent materials, which severely limits the application range of these devices. Therefore, the development of novel dynamic metasurface designs is crucial to unleash the full potential of next-generation optical devices [4] .

Femtosecond laser modification of transparent materials offers selective chemical etching, facilitating three-dimensional (3D) micro-structures to open into flexible shapes as configured by multi-line scanning [1] . While surface aberration and other beam shaping methods have been widely studied in processing of transparent glasses [2] , [3] , the influence of such beam shaping on chemical etching has not been addressed. This paper examines the microstructure resulting in fused silica from beams with concave and convex conical phase front [4] . The conical beam shaping is shown to improve etching rates and surface morphology, compensate for deep focussing aberration and provide an attractive tailoring of the microchannel cross-sectional profile.

Planar diverging lenses attached to the front end of a dielectric rod antenna are proposed to control the heating area on the human body to assist the electroporation treatment of different tumor sizes. The desired 5–7 °C temperature elevation of the tumors is achieved in 3 minutes by applying 2.1-3.6 W input power depending on the size of tumor. In order to treat the tumors located 3–7 mm below the skin surface, the applicator is operated at 8 GHz. The experimental results obtained by measuring a pork muscle tissue show good agreement with electro-thermal simulations.

In this paper, a holographic system to suppress the speckle noise is proposed. Two spatial light modulators (SLMs) are used in the system, one of which is used for beam shaping, and the other is used for reproducing the image. By calculating the effective viewing angle of the reconstructed image, the effective hologram and the effective region of the SLM are calculated accordingly. Then, the size of the diffractive optical element (DOE) is calculated accordingly. The dynamic DOEs and effective hologram are loaded on the effective regions of the two SLMs, respectively, while the wasted areas of the two SLMs are performed with zero-padded operations. When the laser passes through the first SLM, the light can be modulated by the effective DOEs. When the modulated beam illuminates the second SLM which is loaded with the effective hologram, the image is reconstructed with better quality and lower speckle noise. Moreover, the calculation time of the hologram is reduced. Experiments indicate the validity of the proposed system.

Significance Fast submicrometer-scale 3D printing techniques are of interest for various applications ranging from photonics and electronics to tissue engineering. Interference lithography is a versatile 3D printing method with the ability to generate complicated nanoscale structures. Its application, however, has been hindered by either the complicated setups in multibeam lithography that cause sensitivity and impede scalability or the limited level of control over the fabricated structure achievable with mask-assisted processes. Here, we show that metasurface masks can generate complex volumetric intensity distributions with submicrometer scales for fast and scalable 3D printing. These results push the limits of optical devices in controlling the light intensity distribution and significantly increase the realm of possibilities for 3D printing., Fast, large-scale, and robust 3-dimensional (3D) fabrication techniques for patterning a variety of structures with submicrometer resolution are important in many areas of science and technology such as photonics, electronics, and mechanics with a wide range of applications from tissue engineering to nanoarchitected materials. From several promising 3D manufacturing techniques for realizing different classes of structures suitable for various applications, interference lithography with diffractive masks stands out for its potential to fabricate complex structures at fast speeds. However, the interference lithography masks demonstrated generally suffer from limitations in terms of the patterns that can be generated. To overcome some of these limitations, here we propose the metasurface-mask–assisted 3D nanofabrication which provides great freedom in patterning various periodic structures. To showcase the versatility of this platform, we design metasurface masks that generate exotic periodic lattices like gyroid, rotated cubic, and diamond structures. As a proof of concept, we experimentally demonstrate a diffractive element that can generate the diamond lattice.

Beam shaping is required for semiconductor lasers to achieve high optical fiber coupling efficiency in many applications. But the positioning errors on optics may reduce beam shaping effects, and then lead to low optical fiber coupling efficiency. In this work, the positioning errors models for the single emitter laser diode beam shaping system are established. Moreover, the relationships between the errors and the beam shaping effect of each shapers are analysed. Subsequently, the relationship between the errors and the optical fiber coupling efficiency is analysed. The result shows that position errors in the Z axis direction on the fast axis collimator have the greatest influence on the shaping effect, followed by the position errors in the Z axis direction on the converging lens, which should be strictly suppressed in actual operation. Besides, the position errors have a significant influence on the optical fiber coupling efficiency and need to be avoided.

Fluorescence microscopy has long been a valuable tool for biological and medical imaging. Control of optical parameters such as the amplitude, phase, polarization, and propagation angle of light gives fluorescence imaging great capabilities ranging from super-resolution imaging to long-term real-time observation of living organisms. In this review, we discuss current fluorescence imaging techniques in terms of the use of tailored or structured light for the sample illumination and fluorescence detection, providing a clear overview of their working principles and capabilities.

We report a novel beam homogenizer for digital micromirror device lithography system. Such a beam homogenizer contains only one random freeform microlens array (rfMLA). And the rfMLA consists of different freeform microlenses. By the individual design and irregular arrangement of the microlenses, efficient and uniform beam shaping results have been obtained, and the interference patterns in particular are greatly weakened. Compared with traditional beam homogenizer, the energy efficiency has been increased from 62.00% to 69.70%, and the uniformity for incoherent light and coherent light have been improved from 91.93% to 97.60% and from 79.00% to 94.33%, respectively. rfMLA has great potential for enhancing the performance of DMD lithography system and other optical systems, particularly for the homogenization of the beam and the integration of the system.

The Cu(In,Ga)Se2 (CIGS) thin film solar cell is a promising material architecture considering its high photovoltaic (PV) efficiency at low material cost. Recently, the authors demonstrated all lase...

Viewing the trend of beam shaping, beam steering, and metasurface holograms, a reconfigurable graphene-based metasurface is proposed and modeled using the method of moments combined with th...

A freeform lens construction is proposed to form a specific rotation symmetric beam profile with collimation in this paper. In the proposed approach, two freeform surfaces are constructed segment-by-segment using a numerical method based on Snell's law to produce an output beam profile which has both good irradiance uniformity and high collimation. It is shown that as the number of segments used to construct the freeform surfaces increases, the output beam profile approaches the specific profile. A sparse design point freeform surface construction method is additionally proposed which allows the beam profile to approach the desirable distribution with a fewer number of segments. The proposed method is used to construct freeform lenses for producing output beams with two user-defined irradiance patterns, i.e., annular and triangular distributions. The simulation results show that either demonstrated irradiance distribution is close to the specific distribution. Overall, the present results show that the proposed method provides a versatile and efficient approach for designing freeform lenses with a specific distribution of the output beam profile and good collimation.

A Double Layer Beam Shaping Assembly (DLBSA) was designed to produce epithermal neutrons for BNCT purposes. The Monte Carlo N-Particle eXtended program was used as the software to design the DLBSA and phantom. Distribution of epithermal neutron and gamma flux in the DLBSA and phantom and absorbed dose in the phantom were computed using the Particle and Heavy Ion Transport code System program. Testing results of epithermal neutron beam irradiation of the water phantom showed that epithermal neutrons were thermalized and penetrated the phantom up to a depth of 12 cm. The maximum value of the absorbed dose was 2 × 10-3 Gy at a depth of 2 cm in the phantom.

A tractor beam, which has the ability to attract objects, is a class of special optical beams. Currently, people are using the holographic technology to shape complex optical tractor beams for both fundamental research and practical applications. However, most of the work reported is focusing on generating two-dimensional (2D) tractor beams and simple three-dimensional (3D) tractor beams, which has limitations in the further development on mechanism and application of beam shaping. In the present work, we are introducing our study in designing multiple 3D tractor beams with spatial location regulated independently. Meanwhile, each individual beam could be prescribed along arbitrary geometric curve and twisted at arbitrary angles as desired. In our method, the computer-generated hologram (CGH) of each curve is calculated, and all the CGHs are multiplexed and encoded into one phase-only hologram by adding respective linear phase grating such that different 3D curves appeared in the different positions of the focal regions. We experimentally prove that the generation of optical tractor beams at 3D configuration can be readily achieved. The generated beams in the present study are especially useful for applications such as multiple micro-machining optical trapping and complex 3D manipulation.

This paper describes a millimeter-wave thin lens that exhibits different beam-shaping characteristics depending on the polarization of the incident waves. The proposed unit cell topologies, which use multiple rectangular patches and rectangular-slotted grids, enable thinner (= 0.05λ0) and smaller (= 0.168λ0) features than in previous polarization-dependent lenses. An appropriate set of the proposed unit cells is shown to cover a tunable phase range of 180° with respect to one polarized wave but have an almost-zero tunable range of phase shifts with respect to another polarized wave. Thus, using this unit cell set for x-polarized incident waves, the proposed lens operates as a convex lens, whereas for y-polarized incident waves, the lens operates as a frequency selective surface. This confirms that gain variations of 13 dB or more can be differentiated according to the polarization of the incident waves on the lens, supporting polarization-dependent beam-shaping capability as a function of the polarization of incident waves.

Anomalous hollow beams in optical domain were introduced in Cai (2007) and Cai et al. (2008) and as an extension of anomalous hollow electron beams introduced in [Phys. Rev. Lett. 94, 134802 (2005)]. In this paper, for the first time, we demonstrate both theoretically and experimentally that we can obtain a flexible far-field anomalous hollow beam spot of elliptical symmetry with an elliptical solid core through incoherent superposition of two partially coherent sources with different degrees of coherence. The ellipticities and orientation angles of the outer elliptical ring and the inner elliptical solid core are controlled through varying the initial beam parameters. We also demonstrate that incoherent superposition of two partially coherent sources with different degrees of coherence provides a convenient way for constructing various degrees of coherence of the combined source. Our method and results are useful for beam shaping and particle trapping.

In the past 20 years, semiconductor lasers have been widely used in medical, industrial, and communication applications, providing a revolutionary and powerful platform for the fifth generation and advanced manufacturing. Semiconductor laser has the advantages of small size, lightweight, high reliability and easy modulation, becoming increasingly popular. However, due to the laser diode emission mechanism limitation, the beam quality is inferior and cannot be directly applied and required to be handled by beam shaping. However, the packaging of multiple beam shaping optical components is accompanied by risks due to misalignment. The misalignment error of the optical components has a great hidden danger to the laser performance. As semiconductor lasers' power gradually increases, lasers' thermal management technology is also increasingly strict. Therefore, this article first reviews the beam shaping technology of semiconductor laser diode array. Secondly, the analysis of the influence of the array semiconductor laser optical device's misalignment is reviewed, and a feasible solution is proposed. Finally, it summarizes the researches on thermal management in high-power semiconductor lasers. This article aims to give readers a comprehensive and broad understanding of semiconductor laser packaging's technical difficulties and to recognize each corresponding solution.

We report on the separation of complex inner and outer contours from glass articles with curved surfaces using ultrashort pulsed lasers. To achieve single-pass, full-thickness modifications along the entire substrate a processing optics is presented that allows for beam shaping of non-diffracting beams and, additionally, for aberration compensation of phase distortions occurring at the curved interface. The glass articles finally separated by thermal stress or via selective laser etching meet the demands of the medical industry in terms of micro-debris, surface quality and processing speed.

Metasurfaces supply a planar approach for flexible wavefront manipulation, thus facilitating the integration and minimization of optical elements, especially in the terahertz (THz) range. High efficient THz metadevices are highly pursued at present. Here, we propose a bilayer design to improve the efficiency of metadevice. Two silicon pillar arrays with distinguishing geometries are integrated on single silicon substrate. On one side, elliptical silicon pillars, with geometry optimized for the target frequency, are spatially orientated to realize the desired Pancharatnam-Berry phase. On the other side, uniform circular silicon pillars are set to suppress the reflection. With this design, versatile metadevices such as lens, lens array, polarization fork grating, Bessel vortex generator, and Airy beam generator are demonstrated. Maximum efficiency up to 95% for the target frequency and excellent design flexibility are verified. It provides a practical strategy for the generation of compact and high-efficiency THz metadevices, which suit for high-performance THz imaging and communication apparatuses.

Bessel and annular laser beams offer intriguing possibilities for material processing. However, current beam shaping methods can be limited in tunability, speed, or parallelization possibilities. Here, we show how ultrasounds in liquids enable generating user-selectable arrays of Gaussian, Bessel-like, or annular beams. By cascading two liquid-filled acoustic cavities, each with a different geometry, light control can be achieved at microsecond time scales. Such an acousto-optic technology is easy to implement in current laser-direct writing workstations, providing an unprecedented ability to tune light fields based on application.

Different wavelength lasers are widely used in ophthalmology for example for selectively heating certain tissues of the eye or unleashing the potential of photoactive pharmaceuticals. The problem with many ophthalmic laser-based treatments such as photodynamic therapy for age-related macular degeneration is that the laser technology is outdated and no longer supported despite the wide clinical use of these therapy modalities. Modulight has developed a configurable cloud-connected ophthalmic laser device that can house any of Modulight’s semiconductor lasers and is wirelessly controlled with an iPad. In addition to novel ophthalmic laser technology, Modulight has also developed a novel beam shaping unit which yields superior beam quality and enables exceptionally large treatment spots eliminating the need for multi-spot treatment for larger lesions.

We report a new optofluidic transmissive wavefront modulator optimized for gravity-neutral performance and miniaturized dimensions. The modulator is optimized for compensating gravity-induced aberrations by simulating its behavior with various design configurations. Miniaturization was achieved by a novel method for liquid filling and sealing of the modulator. Key elements of the new interface are intra-substrate channels fabricated by a selective laser-induced etching process. The modulator has a final thickness of 750 µm and can be operated in any orientation without significant loss of modulation quality.

We experimentally demonstrate phase encoding in SHG with transparent all-dielectric metasurfaces. While a similar task was previously achieved with plasmonic metasurfaces for THG beam shaping, here we obtain three-order-of-magnitude higher generation efficiency without thermal dissipation.

Several beam shaping strategies have been proposed as an effective approach to fully exploit the average power delivered by the last generation of high power, industrial, femtosecond laser whilst avoiding unwanted thermal effects. Nevertheless, in the case of surface texturing, the effect of the profile modifications on the surface morphology has been barely investigated. The objective of our study is to understand more deeply how the beam profile features will impact the surface evolution. By tailoring the beam profile, we want to understand if it is possible to increase the process throughput. A comprehensive study has been carried out with a 35 W, 2MHz, femtosecond industrial laser. The impact of the beam intensity profile on texturing of metallic surface has been investigated. We systematically studied how the beam size (from 10 μm to few hundreds of microns) impacts the generation and evolution of Laser Induced Periodic Surface Structures (LIPSS) on Stainless Steel surface. SEM analysis has been carried out for all the generated morphologies.

Arrays of patch antennas have impacted modern telecommunications in the RF range significantly, owing to their versatility in tailoring the properties of the emitted radiation such as beam width and polarization, along with their ease of fabrication. At higher frequencies, in the terahertz (THz) range, there is a pressing need for a similar monolithic platform to realize and enable the advanced functionalities available in the RF technology. This platform would benefit a wide variety of fields such as astronomy, spectroscopy, wireless communications, and imaging. Here, we demonstrate THz lasers made of arrays of 10 × 10 patch antenna microcavities that provide up to 25 mW output power with robust single mode frequency and spatial mode. This device architecture leads to an unprecedented beam divergence, better than 2° × 2°, which depends only on the number of resonators. This allows to functionalize the device while preserving a high quality far-field pattern. By interconnecting the symmetric square microcavities with narrow plasmonic wires along one direction, we introduce an asymmetry into the originally degenerate and cross-polarized TM01 and TM10 modes, leading to a precise control of the resonant frequency detuning between the TM modes. This feature allows devices to be designed that radiate with any coherent polarization states from linear to circular. Large-scale full-wave simulations of the emission from entire arrays support our experimental results. Our platform provides a solution to finally achieve monolithic terahertz emitters with advanced integrated functionalities such as active beam steering and polarization control.

We present laser-polished freeform optics used for highly efficient single- and multimode beam shaping. The design freedom provided by truly freeform fabrication allows us to address a wide range of laser applications with control over intensity distribution and uniformity.

•A deep convolutional neural network is used to evaluate and correct the alignment of an orbital angular momentum sorter.•The convolutional neural network automatically analyses OAM spectra at a rate of 50 ms/spectrum, allowing for real time implementation.•The method is easily transferable to any programmable beam shaping technique. A convolutional neural network is used to align an orbital angular momentum sorter in a transmission electron microscope. The method is demonstrated using simulations and experiments. As a result of its accuracy and speed, it offers the possibility of real-time tuning of other electron optical devices and electron beam shaping configurations.