- 标题
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Atom localization using Laguerre-Gaussian beams
摘要： Use of the Laguerre-Gaussian beams in an atom-light interaction makes the linewidth of the optical spectrum narrow. We exploit this fact for providing the ability to accomplish simultaneous ultra-high precision and spatial resolution atom localization in a double-Λ atomic system; under multi-photon resonance condition, the resolution of the localization is remarkably improved so that the atom can be localized in a region smaller than λ/100 × λ/100. Most prominently, the probability of finding the atom at a particular position is always 100%, when a photon with certain frequencies is absorbed or amplified. Such features are mainly attributed to radial dependence associated with the Laguerre-Gaussian beams in a spatially dependent atom-light interaction.
关键词： Laguerre-Gaussian beams,probe absorption,2D atom localization
更新于2025-09-23 15:23:52
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Beam frame representation for ultra-wide-band radiation from volume source distributions: Frequency domain and time domain formulations
摘要： We present two novel beam summation (BS) schemes for radiation from time-harmonic or time-dependent volume source distributions, where the field is expanded using a discrete phase-space set of beam-wave propagators. The generic term “beams” is used here for both the frequency-domain and the time-domain formulations where the propagators are iso-diffracting Gaussian beam (ID-GB) or iso-diffracting pulsed beams (ID-PB), respectively. The formulations are structured upon the recently formulated “beam-frame” theorem that establishes these phase-space beam-sets as frame-sets everywhere in the propagation domain, and not only over the aperture plane as in previous formulations. The expansion coefficients are obtained by projecting the source distributions over the dual beam-frame sets that have essentially the same structure as the basic sets. As such, these formulations constitute local generalization to the conventional plane-waves or Green’s function formulations, and also reduce the overall degrees of freedom needed to describe the radiated field. As demonstrated by the numerical examples they resolve the local features of the source distributions in space-time, and hence provide a basis for a new local inverse scattering theory to be presented subsequently.
关键词： beam summation methods,pulsed beams,Gaussian beams,phase space representations,ultra wide band,time domain,Radiation theory
更新于2025-09-23 15:21:21
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Transformation of Gaussian beams into M-beams for advanced microvia drilling
摘要： Typical laser systems produce Gaussian laser beams that may not be suitable for high precision materials processing. This study considers laser microvia drilling of multilayer polymeric substrates for high density interconnects of microelectronics devices. Closely spaced microvias reduce the interconnect distance between the processors to meet the ever increasing demand for transferring large volumes of data at high rates. CO2 lasers of 9.3 μm wavelength is commonly used for drilling microvias in current polymeric substrates because of their higher absorption coefficient at this wavelength than at 10.6 μm wavelength of conventional CO2 lasers. High absorption coefficient provides a volumetric heating mechanism of shallow depth to enable surface-controlled vaporization of the polymeric materials. Gaussian or top-hat laser beams generally leave carbonized polymeric residue at the bottom corner and on the side wall of the microvias, and this residue hinders the subsequent microsoldering of electronic devices to the interconnects. The formation of the residue can be reduced using M-beams for microvia drilling. A thermal model is developed to determine the intensity distribution of the M-beam. To achieve this M-beam from a Gaussian beam, a lens system is designed using the Fresnel diffraction model. Drilling experiments have been conducted using an M-beam and the shape and size of the microvia are found to match the theoretical predictions very well.
关键词： microvia drilling,high density interconnects,Gaussian beams,CO2 lasers,M-beams,polymeric substrates
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Optical Coupling of 3D Silicon Micromirrors
摘要： Free space optical coupling is considered the important feature which affects on the performance of the optical systems. Where coupling elements such as lenses and mirrors are aided in overcome the divergence of the Gaussian beams and to achieve phase matching. Here we concentrate on the studying of the free space coupling of 3D (spherical) mirror based on the propagation of a Gaussian beam. The design and fabrication of 3D mirror in the Optical microelectromechanical systems (MEMS) are studied. The coupling efficiency is a very important factor in the design of any MEMS circuit. High coupling efficiency is obtained by assembling optical parts which increase the integration effort. In this work, we report a high coupling efficiency, monolithically integrated 3D silicon micromirror that is capable of influencing on the Gaussian beams which propagate in the plane of the silicon substrate. A micromachining method is presented for fabricating the 3D micromirror.
关键词： micromachining,3D silicon micromirrors,optical coupling,MEMS,Gaussian beams
更新于2025-09-23 15:19:57
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Comparative study of laser scribing of Sno2:F thin films using Gaussian and top-hat beams
摘要： Laser scribing is a common method used for manufacturing large-scale solar cells to increase cell efficiency by subdividing large cells into small mini-modules connected in series, decreasing the current produced and therefore reducing the ohmic losses. Introducing large temperature gradients causes thermal expansion and subsequently induced stresses, and these stresses can be used to cause mechanical fracture and material removal. Gaussian beams, which are commonly used in existing scribing practice, have high energy intensity in the center of the beam resulting in unwanted substrate damage as well as excess energy toward the edge of the beam spot. This contributes to the formation of a heat affected zone and partial melting also resulting in large sidewall taper and residual material. The top-hat distribution, having a much more rapid decrease in intensity at the spot edges and more uniform intensity throughout, greatly reduces the likelihood of melting or partial removal on the spot edges, as well as the risk of damage to the glass substrate. However, little work has been done to quantify the differences in the resulting scribe quality of these laser beam intensity distributions. In this study, experiments were carried out on 400 nm thick SnO2:F TCO layer irradiated from the glass side using a 1064 nm Nd:YAG laser with both Gaussian and top-hat intensity distributions. Samples were processed using pulse energies ranging from 5μJ to 30μJ. Pulse repetition rates of 10 kHz were used. Scribe geometry was observed using AFM scans and SEM images. Possible negative effects such as delamination and crack formation resulting from abrupt intensity changes are investigated. A coupled thermo-mechanical finite element model is used to analyze the spatial temperature and stress distributions within the film during the scribing process. Our results find that the top-hat beam profile improves the uniformity and depths of the scribes, but increased thermal effects along the walls are experienced.
关键词： Gaussian beams,thermal ablation,mechanical fracture,SnO2:F thin films,laser scribing,top-hat beams
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Conical Refraction with Laguerre-Gaussian Beams: From Raman Spot to ‘Anti-Raman’ Doughnut Distribution
摘要： Conical refraction (CR) is observed for the light propagating along the optical axis of a biaxial crystal. In this case a narrow beam evolves as a hollow double-walled cylinder of light behind the exit facet of a crystal. Despite of almost two-centuries-long research, CR was slow with practical applications, mainly due to the difficulties associated with cutting of the biaxial crystals with the necessary precision. However, a number of recent papers report on the emerging applications of CR for the realisation of ultra-efficient CR lasers, lasers with CR output, optical trapping with CR beams, utilisation of CR for quantum-computing, cryptography and super-resolution microscopy (see e.g. [1] and references therein). However, one of the most novel and intriguing phenomena within the CR are associated with utilization of vortex input beams. These are capable to completely change the familiar CR patterns [2] and trigger many new applications. In this sense, studies of CR with Laguerre-Gaussian beams LG?0, which are the simplest vortices, may be very fruitful (here, ? is the index determining vortex charge): These already have demonstrated specific new properties of CR, such as formation of a multi-ring image in the Lloyd plane [2]. In this paper, we discuss CR of the LG beams within the dual-cone model [3]. Application of this formalism enables visualization of the Raman spot transformation into the ‘anti-Raman’ doughnut distribution for the non-zeroth order LG input beams. According to the dual-cone model, the Raman spot is formed by the cone-shaped beam that converges towards the optical axis. Having this in mind, one should expect formation of the doughnut distribution downstream from the ‘apex’ of the light cone. However, for LG00 (i.e. Gaussian) input beam, divergence of the light cone behind it’s ‘apex’ is compensated by diffractive divergence, and Raman spot takes it’s ‘focal’ spot shape [4] as shown in figs.1a-c. An increase of the light cone apex angle for the non-zeroth order LG modes results in transformation of the Raman focal spot into the ‘anti-Raman’ doughnut distribution downstream from the ‘apex’ of the light cone (see figs.1d-f). Furthermore, the application of the dual-cone model elegantly explains the transition of the classical double-ring pattern of CR in the Lloyd plane (fig.1a) into a multi-ring one (fig.1d) reported earlier for the LG beams with ?>0 [2]. The natural reason for this transformation lays in the interplay between the conicity that increases for the higher-order LG beams and their increasing beam-waist size. Combination of these two factors results in the broader interference pattern with increased number of condensed fringes.
关键词： Raman spot,Laguerre-Gaussian beams,dual-cone model,Conical refraction,anti-Raman doughnut distribution
更新于2025-09-16 10:30:52
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Plasma volume holograms for focusing and mode conversion of ultraintense laser pulses
摘要： Beating of a broad laser reference beam with a quite general focused object beam inside a plasma volume generates a dynamic plasma hologram. Both beams may be of moderate intensity. The volume hologram can be read out by an ultraintense main beam (of similar structure as the reference beam) producing an object beam replica. For the latter, intensity in the focus may become extremely large. As an application, the possibility of a read-out focused Gaussian laser pulse with intensity of several 1019 W/cm2 in focus is shown by three-dimensional numerical simulations. Besides the focusing possibility, the hologram may also act as a mode converter for high-intensity laser pulses. Generating a plasma hologram with a focused Laguerre-Gaussian object beam results in a staggered plasma density grating, allowing the production of high-intensity vortex beam replica.
关键词： ultraintense laser pulses,Laguerre-Gaussian beams,plasma volume holograms,focusing,mode conversion
更新于2025-09-11 14:15:04
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Real Sources in Complex Spaces
摘要： We utilize complex transformation optics (CTO) to mimic complex source point (CSP) fields. It is shown that the CSP fields can be exactly reproduced via planar metamaterial slabs associated with the proper complex coordinate transformations. CTO extends the real-valued coordinate transformations to complex-valued coordinate transformations. Of conventional TO, one can also control the amplitude of the fields in addition to their phase paths. In the present paper, we demonstrate that CSP fields can be produced through appropriate material tensors prescribed by the corresponding complex coordinate transformations.
关键词： Complex transformation optics,complex source point,metamaterials,Gaussian beams
更新于2025-09-10 09:29:36
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High Precision Position Measurement Method for Laguerre-Gaussian Beams Using a Quadrant Detector
摘要： In this paper, we propose a new method to improve the position measurement accuracy for Laguerre-Gaussian beams on a quadrant detector (QD). First, the error effects of the detector diameter and the gap size are taken into account, and the position error compensation factor is introduced into the conventional formula. Then, in order to reduce the number of parameters, the concept of effective radius is proposed. Thus, a new analytical expression is obtained with a best fit using the least square method. It is verified by simulation that this approach can reduce the maximum error by 97.4% when the beam radius is 0.95 mm; meanwhile, the root mean square errors under different radii are all less than 0.004 mm. The results of simulation show that the new method could effectively improve the accuracy of the QD measurement for different radii. Therefore, the new method would have a good prospect in the engineering practice of beam position measurements.
关键词： quadrant detector,detection,Laguerre-Gaussian beams,effective radius,position measurement method,least square method
更新于2025-09-10 09:29:36
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[OSA CLEO: Science and Innovations - San Jose, California (2015..-..)] CLEO: 2015 - Demonstration of Distance Emulation for an Orbital-Angular-Momentum Beam
摘要： We design and experimentally demonstrate a free-space distance emulator for propagating OAM beams over long distances in a lab environment. The performance of the system is assessed by measuring spot radius and radius of curvature of propagated beams.
关键词： OAM beams,Orbital-angular-momentum,free-space emulator,Laguerre Gaussian beams
更新于2025-09-09 09:28:46