A Deep Ultraviolet Mode-Locked Laser Based on a Neural Network Haoyuan Lu1, Hao Xu1, Jianye Zhao1* & Dong Hou2*
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Graduate Studies in Nuclear Physics At
Graduate Studies in Atomic, Molecular, and Optical Physics at The College of William and Mary Atomic, Molecular, and Optical Group: General Information: Experimental Faculty: 4 The College of William and Mary (W&M), chartered in 1693, Theoretical Faculty: 1 is the second oldest university in the US. It boasts four US Graduate Students: 14 presidents, supreme court justices and Jon Stewart as alumni. Female Students: 5 W&M is a liberal arts university with a strong research focus. Our 7,800 students (2,000 of them graduate students) enjoy a Rankings (US News and World Report): low student-to-faculty ratio, state-of-the-art facilities, and a beautiful campus. W&M ranked 6th amongst public US universities Located in Williamsburg, Virginia, W&M is in the heart of Physics Department Statistics: colonial American history and is adjacent to Colonial Average annual number of Ph. D. recipients: 8 Williamsburg, a historic recreation of 18th century colonial Average time to Ph. D.: 5 years life. While much of the campus has been restored to its 18th- century appearance, the physics department is housed in a Departmental Website: newly refurbished and expanded building that provides http://www.wm.edu/physics outstanding teaching and research space. http://www.wm.edu/as/physics/research/index.php The William and Mary physics department benefits Graduate Admissions: enormously from close ties with both Thomas Jefferson http://www.wm.edu/as/physics/grad/index.php National Accelerator Facility (JLab) and NASA Langley Application deadline: Feb 1st Research Center in nearby Newport News (thirty minutes from the W&M campus). -
Direct Frequency Comb Laser Cooling and Trapping
Selected for a Viewpoint in Physics PHYSICAL REVIEW X 6, 041004 (2016) Direct Frequency Comb Laser Cooling and Trapping A. M. Jayich,* X. Long, and W. C. Campbell Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA and California Institute for Quantum Emulation, Santa Barbara, California 93106, USA (Received 11 May 2016; published 10 October 2016) Ultracold atoms, produced by laser cooling and trapping, have led to recent advances in quantum information, quantum chemistry, and quantum sensors. A lack of ultraviolet narrow-band lasers precludes laser cooling of prevalent atoms such as hydrogen, carbon, oxygen, and nitrogen. Broadband pulsed lasers can produce high power in the ultraviolet, and we demonstrate that the entire spectrum of an optical frequency comb can cool atoms when used to drive a narrow two-photon transition. This multiphoton optical force is also used to make a magneto-optical trap. These techniques may provide a route to ultracold samples of nature’s most abundant building blocks for studies of pure-state chemistry and precision measurement. DOI: 10.1103/PhysRevX.6.041004 Subject Areas: Atomic and Molecular Physics I. INTRODUCTION ultraviolet means that laser cooling and trapping is not currently available for the most prevalent atoms in organic High-precision physical measurements are often under- chemistry: hydrogen, carbon, oxygen, and nitrogen. taken close to absolute zero temperature to minimize Because of their simplicity and abundance, these species, thermal fluctuations. For example, the measurable proper- with the addition of antihydrogen, likewise play prominent ties of a room temperature chemical reaction (rate, roles in other scientific fields such as astrophysics [11] and product branching, etc.) include a thermally induced precision measurement [12], where the production of average over a large number of reactant and product cold samples could help answer fundamental outstanding quantum states, which masks the unique details of questions [13–15]. -
Unraveling Resistive Versus Collisional Contributions to Relativistic Electron Beam Stopping Power in Cold-Solid and in Warm-Dense Plasmas B
Unraveling resistive versus collisional contributions to relativistic electron beam stopping power in cold-solid and in warm-dense plasmas B. Vauzour,1, 2 A. Debayle,3, 4 X. Vaisseau,1 S. Hulin,1 H.-P. Schlenvoigt,5 D. Batani,1, 6 S.D. Baton,5 J.J. Honrubia,3 Ph. Nicola¨ı,1 F.N. Beg,7 R. Benocci,6 S. Chawla,7 M. Coury,8 F. Dorchies,1 C. Fourment,1 E. d'Humi`eres,1 L.C. Jarrot,7 P. McKenna,8 Y.J. Rhee,9 V.T. Tikhonchuk,1 L. Volpe,6 V. Yahia,5 and J.J. Santos1, a) 1)Univ. Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence, France 2)Laboratoire d'Optique Appliqu´ee,ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau, France 3)ETSI Aeron´auticos, Universidad Polit´ecnica de Madrid, Madrid, Spain 4)CEA, DAM, DIF, F-91297 Arpajon, France 5)LULI, Ecole Polytechnique CNRS/CEA/UPMC, 91128 Palaiseau Cedex, France 6)Dipartimento di Fisica, Universit`adi Milano-Bicocca, Milano 20126, Italy 7)University of California, San Diego, La Jolla, California 92093, USA 8)SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom 9)Korea Atomic Energy Research Institute (KAERI), Daejon 305-600, Korea (Dated: 18 February 2014) We present results on laser-driven relativistic electron beam propagation through aluminum samples, which are either solid and cold, or compressed and heated by laser-induced shock. A full numerical description of fast electron generation and transport is found to reproduce the experimental absolute Kα yield and spot size measurements for varying target thickness, and to sequentially quantify the collisional and resistive electron stopping powers. -
Influence of the Conditions of Selective Laser Melting on Evaporation
MATEC Web of Conferences 224, 01060 (2018) https://doi.org/10.1051/matecconf/201822401060 ICMTMTE 2018 Influence of the conditions of selective laser melting on evaporation Roman S. Khmyrov1,*, Сyrill E. Protasov1, and Andrey V. Gusarov1 1Moscow State University of Technology “STANKIN”, 127055, Vadkovskii per. 1, Moscow, Russia Abstract. The paper presents the results of optical diagnostics of evaporation and displacement of powder fractions during the formation of a single track in the process of selective laser melting. The velocity of the powder fractions is estimated. It was defined, that an increase in the scanning speed leads to an decrease in the particle coming out rate from the molten pool and the rate at which they are attracted. The results allow evaluating the kinetics of the mass-transfer process during selective laser melting. It was clearly shown the material quality properties after the selective laser melting are strongly influenced by the formed thermal field in the laser-irradiated zone. 1 Introduction Laser material processing becomes already quite common in the modern industry, for example such processes as laser cutting, welding, drilling, marking. Technologies of additive manufacturing (growing) of parts from metal powders are also becoming more popular and characterizing by fundamentally different manufacturing strategy: layer by layer. It should be mentioned, that the lack of theoretical apparatus describing the process technology is the fundamental problem in the field of laser treatment. Such fundamental problems which are necessary to solve are: powder consolidation kinetics and its dependence of process parameters, intensive powder release (slopping) from powder consolidation zone: its causes, methods of influence on it; physical mechanisms leading to geometry instability of fused bead, instability at overcharged and undercharged scanning speeds of the laser beam relative to the optimal values, mechanisms of integration of individual track in a single one. -
Three-Dimensional Laser Cooling at the Doppler Limit R
Three-dimensional laser cooling at the Doppler limit R. Chang, A. L. Hoendervanger, Q. Bouton, Y. Fang, T. Klafka, K. Audo, Alain Aspect, C. I. Westbrook, D. Clément To cite this version: R. Chang, A. L. Hoendervanger, Q. Bouton, Y. Fang, T. Klafka, et al.. Three-dimensional laser cooling at the Doppler limit. Physical Review A, American Physical Society, 2014, 90 (6), pp.063407. 10.1103/PhysRevA.90.063407. hal-01068704 HAL Id: hal-01068704 https://hal.archives-ouvertes.fr/hal-01068704 Submitted on 22 Feb 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Copyright Three-Dimensional Laser Cooling at the Doppler limit R. Chang,1 A. L. Hoendervanger,1 Q. Bouton,1 Y. Fang,1, 2 T. Klafka,1 K. Audo,1 A. Aspect,1 C. I. Westbrook,1 and D. Cl´ement1 1Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ. Paris Sud, 2 Avenue Augustin Fresnel 91127 PALAISEAU cedex, France 2Quantum Institute for Light and Atoms, Department of Physics, State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241, China Many predictions of Doppler cooling theory of two-level atoms have never been verified in a three- dimensional geometry, including the celebrated minimum achievable temperature ~Γ=2kB , where Γ is the transition linewidth. -
Flow Diagnostics Produced by Selective Laser Melting of Cutting Nozzles
Lasers in Manufacturing Conference 2015 Flow diagnostics produced by selective laser melting of cutting nozzles S.Ulricha, S.Lorenza S. Jahna, S.Sändiga, B.Fleckb aGünter-Köhler-Institut für Fügetechnik und Werkstoffprüfung GmbH bErnst-Abbe-Hochschule Jena Abstract The increasing spread of laser technology in materials processing leads inter alia increasingly individual solution strategies in order to cope with the growing demands on the process control. The focus of this work is the fluidic analysis of the cutting nozzles, which were usually produced either by selective laser melting or conventional methods. The Schlieren measurement was utilized in order to visualize flows. Through the adjustment of optical components, the Schlieren-Aufnahmegerät 80 was coupled with a high speed camera. Based on these measurement results, the influence of manufacturing technology has been evaluated on the flow behaviour. With the help of cutting tests a direct proof of the achievable quality of the cutting edge has been evaluated. The results from both research methods provide a statement on the quality of the gas stream and the achievable cutting quality of manufacturing technology. Keywords: laser cutting, selektiv laser melting, nozzle, flow visualization 1. Introduction Nowadays, the decisive factors for financial success are on the one hand innovative products, and on the other hand the acquisition of knowledge through research and development. In materials processing, the application of lasers in technological fields like cutting and welding, enables shorter lead times. The understanding of the process plays a crucial role for the quality of the component. Regarding cutting, the quality of the cut edge and the dimensional accuracy is affected by many parameters. -
Laser Cooling of Two Trapped Ions: Sideband Cooling Beyond the Lamb-Dicke Limit
PHYSICAL REVIEW A VOLUME 59, NUMBER 5 MAY 1999 Laser cooling of two trapped ions: Sideband cooling beyond the Lamb-Dicke limit G. Morigi,1 J. Eschner,2 J. I. Cirac,1 and P. Zoller1 1Institut fu¨r Theoretische Physik, Universita¨t Innsbruck, A-6020 Innsbruck, Austria 2Institut fu¨r Experimentalphysik, Universita¨t Innsbruck, A-6020 Innsbruck, Austria ~Received 8 December 1998! We study laser cooling of two ions that are trapped in a harmonic potential and interact by Coulomb repulsion. Sideband cooling in the Lamb-Dicke regime is shown to work analogously to sideband cooling of a single ion. Outside the Lamb-Dicke regime, the incommensurable frequencies of the two vibrational modes result in a quasicontinuous energy spectrum that significantly alters the cooling dynamics. The cooling time decreases nonlinearly with the linewidth of the cooling transition, and the effect of dark states which may slow down the cooling is considerably reduced. We show that cooling to the ground state is also possible outside the Lamb-Dicke regime. We develop the model and use quantum Monte Carlo calculations for specific examples. We show that a rate equation treatment is a good approximation in all cases. @S1050-2947~99!11605-6# PACS number~s!: 32.80.Pj, 42.50.Vk, 03.67.Lx I. INTRODUCTION sideband cooling of two ions to the ground state has been achieved in a Paul trap that operates in the Lamb-Dicke limit The emergence of schemes that utilize trapped ions or @11#. However in this experiment the Lamb-Dicke regime atoms for quantum information, and the interest in quantum required such a high trap frequency that the distance between statistics of ultracold atoms, have provided renewed interest the ions does not allow their individual addressing with a and applications for laser cooling techniques @1#. -
Laser Cooling Yb + Ions with an Optical Frequency Comb
UNIVERSITY OF CALIFORNIA Los Angeles Laser cooling Yb+ ions with optical frequency comb A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Physics by Michael Ip 2018 c Copyright by Michael Ip 2018 ABSTRACT OF THE DISSERTATION Laser cooling Yb+ ions with optical frequency comb by Michael Ip Doctor of Philosophy in Physics University of California, Los Angeles, 2018 Professor Wesley C. Campbell, Chair Trapped atomic ions are a multifaceted platform that can serve as a quan- tum information processor, precision measurement tool and sensor. How- ever, in order to perform these experiments, the trapped ions need to be cooled substantially below room temperature. Doppler cooling has been a tremendous work horse in the ion trapping community. Hydrogen-like ions are good candidates because they have typically have a simple closed cycling transition that requires only a few lasers to Doppler cool. The 2S to 2P transition for these ions however typically lies in the UV to deep UV regime which makes buying a standard CW laser difficult as optical power here is hard to come by. Rather using a CW laser, which requires frequency stabilization and produces low optical power, this thesis explores how a mode-locked laser in the comb regime Doppler cools Yb ions. This thesis explores how a mode-locked laser is able to laser cool trapped ions and the consequences of using a broad spectrum light source. I will first give an overview of the architecture of our oblate Paul trap. Then I will discuss how a 10 picosecond optical pulse with a repetition rate of 80 MHz 2 2 interacts with a 20 MHz linewidth S1=2 to P1=2 transition. -
Acrylic-Processing-Guide.Pdf
Laser Processing Guide working with acrylic www.troteclaser.com www.trotec-materials.com Acrylic is becoming an increasingly popular manufacturing material used across many industries for a wide range of products such as signs, displays and trophies, to name a few. It is highly versatile, durable, aesthetically pleasing, and processes well with a laser. For many, acrylic is a convenient and affordable alternative to glass because it’s largely impact-resistant and weighs about half as much, but still offers a high level of clarity. A laser is a highly effective and efficient way to cut, mark or engrave acrylic. Including general processing instructions and pointers, time-saving tricks and troubleshooting advice, the following guide was designed to help new laser users as well as intermediate users improve their acrylic processing technique and results. With a little practice and a few pointers, you will be able to use your laser to create perfectly polished acrylic edges, engrave intricate details, and produce precise cuts and contours. Getting 01 Started Engraving Processing Techniques and 02 Recommended Settings Cutting Processing Techniques and 03 Recommended Settings Common 05 Mistakes Trouble 06 Shooting Getting Started Acrylic materials come in a wide range of color, texture, and finish combinations. There are three main types of acrylic: Cell Cast Acrylic that is cast into shapes • Laser engraving appears frosted • Laser cutting easy Continuous Cast Acrylic that is continuously casted into sheets using a sheet shape molded on an assembly line • Laser engraving appears frosted • Laser cutting easy Extruded • Laser engraving is translucent, making it difficult to see • Can be easily cut with a laser using lower power settings. -
Techniques in Laser Cutting and Engraving Leather
Where the Laser Meets the Leather: Techniques in Laser Cutting and Engraving Leather SARAH PIKE If you had ever told me that, as an artist trained in traditional figurative painting who works in stone lithography, I would end up running a laser cutting business, I wouldn't have believed you. But it was through my printmaking discipline and sensibilities that I came to work with laser cutting. And today I draw great satisfaction in helping artists—primarily bookbinders—bridge the gap between handcraft and new technologies. In this article I will share a variety of laser cutting and engraving techniques for working with leather and parchment. A Look at What's Possible Laser cutters, which vaporize material using a pulsating That said, the question I most often get is, “Can you cut beam of light, perform three main tasks: they cut, line metal?” The answer is no: a fiber laser is needed for engrave, and area engrave. When the laser cuts or line laser cutting metal. Due to their size and cost, fiber engraves, it follows the path of the line; when it area lasers are more often found at businesses that service engraves it moves back and forth like an ink-jet printer. industrial companies. Note that in this context, engraving refers to the partial removal of material that can be performed at multiple While I'll try to be as specific as possible, so many depths (fig. 1). variables come into play that it's difficult to give universal guidelines. Laser cutter settings can vary greatly depending on how the leather was processed, the dye used, what part of the skin is being used, and the life of the animal. -
The Effect of the Laser Incidence Angle in the Surface of L-PBF
coatings Article The Effect of the Laser Incidence Angle in the Surface of L-PBF Processed Parts Sara Sendino 1,* , Marc Gardon 2, Fernando Lartategui 3 , Silvia Martinez 1 and Aitzol Lamikiz 1 1 Aerospace Advance Manufacturing Research Center-CFAA, P. Tecnológico de Bizkaia 202, 48170 Zamudio, Spain; [email protected] (S.M.); [email protected] (A.L.) 2 EMEA AM Applications Manager, Renishaw Ibérica, Carrer de la Recerca 7, 08850 Barcelona, Spain; [email protected] 3 UO Structures & Statics, ITP Aero, P. Tecnológico de Bizkaia 300, 48170 Zamudio, Spain; [email protected] * Correspondence: [email protected] Received: 29 September 2020; Accepted: 22 October 2020; Published: 24 October 2020 Abstract: The manufacture of multiple parts on the same platform is a common procedure in the Laser Powder Bed Fusion (L-PBF) process. The main advantage is that the entire working volume of the machine is used and a greater number of parts are obtained, thus reducing inert gas volume, raw powder consumption, and manufacturing time. However, one of the main disadvantages of this method is the possible differences in quality and surface finish of the different parts manufactured on the same platform depending on their orientation and location, even if they are manufactured with the same process parameters and raw powder material. Throughout this study, these surface quality differences were studied, focusing on the variation of the surface roughness with the angle of incidence of the laser with respect to the platform. First, a characterization test was carried out to understand the behavior of the laser in the different areas of the platform. -
Analysis of Stainless Steel Waste Products Generated During Laser Cutting in Nitrogen Atmosphere
Article Analysis of Stainless Steel Waste Products Generated during Laser Cutting in Nitrogen Atmosphere Maciej Zubko 1,2,* , Jan Loskot 2 , Paweł Swiec´ 1 , Krystian Prusik 1 and Zbigniew Janikowski 3 1 Institute of Materials Engineering, University of Silesia in Katowice, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland; [email protected] (P.S.);´ [email protected] (K.P.) 2 Department of Physics, University of Hradec Králové, Rokitanského 62, 500-03 Hradec Králové, Czech Republic; [email protected] 3 “Silver” PPHU, ul. Rymera 4, 44-270 Rybnik, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-32-3497-509; Fax: +48-32-3497-594 Received: 22 October 2020; Accepted: 23 November 2020; Published: 25 November 2020 Abstract: Laser cutting technology is one of the basic approaches used for thermal processing of parts fabricated from almost all engineering materials. Various types of lasers are utilized in the industry with different attendant gases such as nitrogen or argon. When the laser beam interacts with a metal surface, the area underneath is heated to the melting point. This liquid or vaporized metal is ejected from the kerf area to the surrounding atmosphere by attendant gas and becomes undesirable waste in the form of powder. In the presented work, the X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy methods were used to analyze AISI 304 stainless steel, which was cut by a semiconductor fiber laser, and the waste powder generated during the laser cutting process. The results suggest that this waste material may be reused for industrial applications such as additive manufacturing.