Chapter 12 ULTRASHORT LASERS and THEIR BIOEFFECTS
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Part 2: Laser in Pulsed Operation
Part 2: Laser in pulsed operation 1 Theoretical principles 1.1 Generation of short laser pulses The output power of existing continuous wave laser systems is between a few milliwatts (He-Ne lasers) and a few hundred watts (Nd or CO2 lasers). However, there is a possibility to increase the output power of the laser for a small period of time by pulsed laser operation. Solid-state lasers are particularly suitable for this purpose, as they can achieve pulse peak output powers of up to 1012 W. This value corresponds approximately to the average electrical energy generation of the entire world. The difference, however, lies in the period in which this performance is achieved. While all the power plants together reach this value continuously, a single laser produces this high output power only for a duration of 10−13 s. In this case, the extremely short pulse duration appears to be disadvantageous, but there are also applications which exactly require this. One example is laser ablation, which is a method in material processing. Here, a small volume of material at the surface of a work piece can be evaporated if it is heated high enough in a very short amount of time. On the other hand, supplying the energy gradually would allow the heat to be absorbed into the bulk of the piece, never attaining a sufficiently high temperature above the evaporation point of the material. Other applications rely on the very high peak pulse power to obtain strong non-linear optical effects, like it is necessary for efficient second-harmonic generation or for optical parametric oscillators (OPO) which converts an input laser wave into two output waves of lower frequencies. -
Practical Tips for Two-Photon Microscopy
Appendix 1 Practical Tips for Two-Photon Microscopy Mark B. Cannell, Angus McMorland, and Christian Soeller INTRODUCTION blue and green diode lasers. To provide an alignment beam to which the external laser can be aligned, light from this reference As is clear from a number of the chapters in this volume, 2-photon laser needs to be bounced back through the microscope optical microscopy offers many advantages, especially for living-cell train and out through the external coupling port: studies of thick specimens such as brain slices and embryos. CAUTION: Before you switch on the reference laser in this However, these advantages must be balanced against the fact that configuration make sure that all PMTs are protected and/or commercial multiphoton instrumentation is much more costly than turned off. the equipment used for confocal or widefield/deconvolution. Given Place a front-surface mirror on the stage of the microscope and these two facts, it is not surprising that, to an extent much greater focus onto the reflective surface using an air objective for conve- than is true of confocal, many researchers have decided to add a nience (at sharp focus, you should be able to see scratches or other femtosecond (fs) pulsed near-IR laser to a scanner and a micro- mirror defects through the eyepieces). The idea of this method is scope to make their own system (Soeller and Cannell, 1996; Tsai to cause the reference laser beam to bounce back through the et al., 2002; Potter, 2005). Even those who purchase a commercial optical train and emerge from the other laser port. -
Improved Laser Based Photoluminescence on Single-Walled Carbon Nanotubes
Improved laser based photoluminescence on single-walled carbon nanotubes S. Kollarics,1 J. Palot´as,1 A. Bojtor,1 B. G. M´arkus,1 P. Rohringer,2 T. Pichler,2 and F. Simon1 1Department of Physics, Budapest University of Technology and Economics and MTA-BME Lend¨uletSpintronics Research Group (PROSPIN), P.O. Box 91, H-1521 Budapest, Hungary 2Faculty of Physics, University of Vienna, Strudlhofgasse 4., Vienna A-1090, Austria Photoluminescence (PL) has become a common tool to characterize various properties of single- walled carbon nanotube (SWCNT) chirality distribution and the level of tube individualization in SWCNT samples. Most PL studies employ conventional lamp light sources whose spectral dis- tribution is filtered with a monochromator but this results in a still impure spectrum with a low spectral intensity. Tunable dye lasers offer a tunable light source which cover the desired excitation wavelength range with a high spectral intensity, but their operation is often cumbersome. Here, we present the design and properties of an improved dye-laser system which is based on a Q-switch pump laser. The high peak power of the pump provides an essentially threshold-free lasing of the dye laser which substantially improves the operability. It allows operation with laser dyes such as Rhodamin 110 and Pyridin 1, which are otherwise on the border of operation of our laser. Our sys- tem allows to cover the 540-730 nm wavelength range with 4 dyes. In addition, the dye laser output pulses closely follow the properties of the pump this it directly provides a time resolved and tunable laser source. -
University of Southampton Research Repository Eprints Soton
University of Southampton Research Repository ePrints Soton Copyright © and Moral Rights for this thesis are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder/s. The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holders. When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given e.g. AUTHOR (year of submission) "Full thesis title", University of Southampton, name of the University School or Department, PhD Thesis, pagination http://eprints.soton.ac.uk UNIVERSITY OF SOUTHAMPTON FACULTY OF ENGINEERING, SCIENCE AND MATHEMATICS Optoelectronics Research Centre Polarization engineering with ultrafast laser writing in transparent media by Martynas Beresna Thesis for the degree of Doctor of Philosophy August 2012 UNIVERSITY OF SOUTHAMPTON ABSTRACT FACULTY OF ENGINEERING, SCIENCE AND MATHEMATICS OPTOELECTRONICS RESEARCH CENTRE Doctor of Philosophy Polarization engineering with ultrafast laser writing in transparent media By Martynas Beresna In this thesis novel developments in the field of femtosecond laser material processing are reported. Thanks to the unique properties of light-matter interaction on ultrashort time scales, this direct writing technique allowed the observation of unique phenomena in transparent media and the engineering of novel polarization devices. Using tightly focused femtosecond laser pulses’, high average power second harmonic light was generated in the air with two orders of magnitude higher normalised efficiency than reported by earlier studies. -
Two-Photon-Excited Fluorescence (TPEF) and Fluorescence Lifetime Imaging (FLIM) with Sub-Nanosecond Pulses and a High Analog Bandwidth Signal Detection
Two-photon-excited fluorescence (TPEF) and fluorescence lifetime imaging (FLIM) with sub-nanosecond pulses and a high analog bandwidth signal detection Matthias Eibl1, Sebastian Karpf2, Hubertus Hakert1, Daniel Weng1, and Robert Huber1 1Institut für Biomedizinische Optik, Universität zu Lübeck, Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany 2Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA ABSTRACT Two-photon excited fluorescence (TPEF) microscopy and fluorescence lifetime imaging (FLIM) are powerful imaging techniques in bio-molecular science. The need for elaborate light sources for TPEF and speed limitations for FLIM, however, hinder an even wider application. We present a way to overcome this limitations by combining a robust and inexpensive fiber laser for nonlinear excitation with a fast analog digitization method for rapid FLIM imaging. The applied sub nanosecond pulsed laser source is synchronized to a high analog bandwidth signal detection for single shot TPEF- and single shot FLIM imaging. The actively modulated pulses at 1064nm from the fiber laser are adjustable from 50ps to 5ns with kW of peak power. At a typically applied pulse lengths and repetition rates, the duty cycle is comparable to typically used femtosecond pulses and thus the peak power is also comparable at same cw-power. Hence, both types of excitation should yield the same number of fluorescence photons per time on average when used for TPEF imaging. However, in the 100ps configuration, a thousand times more fluorescence photons are generated per pulse. In this paper, we now show that the higher number of fluorescence photons per pulse combined with a high analog bandwidth detection makes it possible to not only use a single pulse per pixel for TPEF imaging but also to resolve the exponential time decay for FLIM. -
Time-Resolved Studies of Nd:YAG Loser-Induced Breakdown
Time-Resolved Studies of Nd:YAG Loser-Induced Breakdown Plasma Formation, Acoustic Wave Generation, and Cavitation Jomes G. Fujimoro,* Wei Z. Liaf Erich P. Ippen,* Carmen A. PuliQfiro4 and Roger F. Sreinerr^: The use of high intensity ultrashort pulsed laser radiation to produce optical breakdown is an important approach for the surgical treatment of intraocular structures. We have investigated the transient properties of Nd:YAG laser induced breakdown in a saline model using time-resolved spectroscopic techniques. Spatially resolved pump and probe techniques are applied to study the dynamic behavior of the plasma formation, acoustic wave generation, and cavitation processes which accompany the optical breakdown. Measurements of plasma shielding and luminescence indicate that the laser induced plasma forms on a subnanosecond time scale and has a lifetime of several nanoseconds. An acoustic transient is generated at the breakdown site and propagates spherically outward with an initial hypersonic velocity, then loses energy and propagates at sound velocity. Transient heating following the plasma formation produces a liquid-gas phase change and gives rise to cavitation or gas bubble formation. This gas bubble expands rapidly for several microseconds, then slows to reach its maximum size and finally collapses. Invest Ophthalmol Vis Sci 26:1771-1777, 1985 Short pulsed Q-switched and modelocked Nd:YAG important role in protecting the retina from the inci- lasers have recently achieved widespread use in dent laser energy,10"12'25"28 while the -
Angwcheminted, 2000, 39, 2587-2631.Pdf
REVIEWS Femtochemistry: Atomic-Scale Dynamics of the Chemical Bond Using Ultrafast Lasers (Nobel Lecture)** Ahmed H. Zewail* Over many millennia, humankind has biological changes. For molecular dy- condensed phases, as well as in bio- thought to explore phenomena on an namics, achieving this atomic-scale res- logical systems such as proteins and ever shorter time scale. In this race olution using ultrafast lasers as strobes DNA structures. It also offers new against time, femtosecond resolution is a triumph, just as X-ray and electron possibilities for the control of reactivity (1fs 10À15 s) is the ultimate achieve- diffraction, and, more recently, STM and for structural femtochemistry and ment for studies of the fundamental and NMR spectroscopy, provided that femtobiology. This anthology gives an dynamics of the chemical bond. Ob- resolution for static molecular struc- overview of the development of the servation of the very act that brings tures. On the femtosecond time scale, field from a personal perspective, en- about chemistryÐthe making and matter wave packets (particle-type) compassing our research at Caltech breaking of bonds on their actual time can be created and their coherent and focusing on the evolution of tech- and length scalesÐis the wellspring of evolution as a single-molecule trajec- niques, concepts, and new discoveries. the field of femtochemistry, which is tory can be observed. The field began the study of molecular motions in the with simple systems of a few atoms and Keywords: femtobiology ´ femto- hitherto unobserved ephemeral transi- has reached the realm of the very chemistry ´ Nobel lecture ´ physical tion states of physical, chemical, and complex in isolated, mesoscopic, and chemistry ´ transition states 1. -
Optimizing Energy Absorption for Ultrashort Pulse Laser Ablation of Fused Silica
Optimizing Energy Absorption for Ultrashort Pulse Laser Ablation of Fused Silica Nicolas Sanner, Maxime Lebugle, Nadezda Varkentina, Marc Sentis and Olivier Utéza Aix-Marseille Univ., CNRS, LP3 UMR 7341, 163 avenue de Luminy C.917, 13288 Marseille, France Keywords: Ultrashort Laser-matter Interaction, Dielectric Materials, Ablation. Abstract: We investigate the ultrafast absorption of fused silica irradiated by a single 500 fs laser pulse in the context of micromachining applications. As the absorption of the laser energy is rapid (~fs), the optical properties of the material evolve during the laser pulse, thereby yielding a feedback on the dynamics of absorption and consequently on the amount of energy that is absorbed. Through complete investigation of energy absorption, by combining “pump depletion” and “pump-probe” experiments in a wide range of incident fluences above the ablation threshold, we demonstrate the existence of an optimal fluence range, enabling to turn transiently the material into a state such that each photon is optimally utilized for ablation. 1 INTRODUCTION processing at micro- and nano-scales: voids for memories, channels for microfluidic, Ultrashort laser pulses are extremely interesting and ophthalmic/neuronal surgery, material cutting, powerful tools for laser-matter interaction. The drilling, surface structuration (e.g. for metamaterials spatial accuracy of energy deposition into matter or plasmonics), etc. All these cutting-edge combined with the shortness of the energy applications for future technology and industry are deposition step enable to reach relatively high based on ultrafast laser-induced ionization of intensities (1013-1014 W.cm-2) while using low dielectric solids, which provides time- and space- energies, capable to push matter into strongly non- confinement of energy for matter transformation. -
Design and Verification of a Multi-Terawatt Ti-Sapphire Femtosecond Laser System
University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2017 Design and Verification of a Multi-Terawatt Ti-Sapphire Femtosecond Laser System Patrick Roumayah University of Central Florida Part of the Optics Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Masters Thesis (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Roumayah, Patrick, "Design and Verification of a Multi-Terawatt Ti-Sapphire Femtosecond Laser System" (2017). Electronic Theses and Dissertations, 2004-2019. 5404. https://stars.library.ucf.edu/etd/5404 DESIGN AND VERIFICATION OF A MULTI-TERAWATT TI-SAPPHIRE FEMTOSECOND LASER SYSTEM by PATRICK ROUMAYAH B.S. University of Michigan, 2011 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the College of Optics and Photonics at the University of Central Florida Orlando, Florida Spring Term 2017 Major Professor: Martin Richardson ABSTRACT Ultrashort pulse lasers are well-established in the scientific community due to the wide range of applications facilitated by their extreme intensities and broad bandwidth capabilities. This thesis will primarily present the design for the Mobile Ultrafast High Energy Laser Facility (MU-HELF) for use in outdoor atmospheric propagation experiments under development at the Laser Plasma Laboratory at UCF. The system is a 100fs 500 mJ Ti-Sapphire Chirped-Pulse Amplification (CPA) laser, operating at 10 Hz. -
Functional Surface Formation by Efficient Laser Ablation Using Single- Pulse and Burst-Modes
Functional surface formation by efficient laser ablation using single- pulse and burst-modes Andrius Žemaitis, Mantas Gaidys, Justinas Mikšys, Paulius Gečys, Mindaugas Gedvilas* Department of Laser Technologies (LTS), Center for Physical Sciences and Technology (FTMC), Savanorių Ave. 231, LT-02300 Vilnius, Lithuania ABSTRACT Surfaces inspired by nature and their replication find great interest in science, technology, and medicine due to their unique functional properties. This research aimed to develop an efficient laser milling technology using single-pulse- and burst-modes of irradiation to replicate bio-inspired structures over large areas at high speed. The ability to form the trapezoidal-riblets inspired by shark skin at high production speeds while maintaining the lowest possible surface roughness was demonstrated. Keywords: functional surface, bio-inspired structure, efficient laser ablation, laser milling, shark skin. 1. INTRODUCTION Ultrafast lasers have been wildly applied in high-throughput microfabrication and patterning of metals1–45, semiconductors6,7, and insulators8–11 in science12–18, technology19–27, and medicine28,29. However, their industrial applications are restricted by the low laser machining rates and the high price of ultrashort laser irradiation sources. The theoretical investigation confirmed by experimental data which clarified the maximizing the ablated volume per laser pulse by the controlling beam radius on the sample and its related laser fluence was conducted more than a decade ago30. The state-of-the-art scientific investigation of laser ablation efficiency suggested the ratio of laser peak fluence to the ablation threshold close to e2 ≈ 7.39 for the maximum material ejection rate and the most efficient ablation point30,31. Since then, laser ablation efficiency has been investigated in numerous papers in independent groups32–41. -
Table of Contents
ICPEPA-8 Collected Abstracts August 12-17, 2012 Institute of Optics University of Rochester Rochester, New York Table of Contents: Oral Presentations 1 Monday 1 SESSION 1: UV Laser Interactions with Materials 1 SESSION 2: Carbon Based Materials 4 SESSION 3: Nanosecond and Longer Timescale Phenomena 10 SESSION 4: Time-Resolved Femtosecond and Picosecond Phenomena 14 Tuesday 19 SESSION 5: MAPLE and Light Emitting Devices 19 SESSION 6: Pulsed Laser Ablation and Nanoparticle Formation 23 SESSION 7: Femtosecond Laser Ablation and its Applications I 27 SESSION 8: Plasmonics 32 Wednesday 34 SESSION 9: Ultrafast Processing of Transparent Materials I 34 SESSION 10: Fabrication of Nano/Micropatterns 37 Thursday 41 SESSION 11: Ultrafast Processing of Transparent Materials II 41 SESSION 12: Femtosecond Laser Ablation and its Applications II 44 SESSION 13: Acoustic Wave, and Laser-Assisted Formation 50 SESSION 14: Photonics and Laser Systems 54 Friday 58 SESSION 15: Laser Interactions with Polymers 58 SESSION 16: HHG and X-ray Interactions with Materials 60 Posters 64 Monday 64 Tuesday 86 The interaction of UV laser light with single crystal ZnO: fundamental studies Tom Dickinson Department of Physics Washington State University Pullman, WA UV-Laser interactions with wide bandgap insulators and semiconductors has generated a number of examples of point defect production, surface and bulk modification, etching and re-deposition processes, as well as numerous PLD related applications involving the emitted particles. In this talk we examine these phenomena and modifications in oriented single crystals of the transparent semiconductor ZnO which as a band-gap of ~3.4 eV. This material is of high interest for production of transparent conductors and transistors, solar cells, lasers, sensors, and in catalysis (including potential use in the photo-dissociation of water). -
Generation, Characterization and Applications of Ultrashort Laser Pulses
Université du Québec Institut National de la Recherche Scientifique Centre Énergie, Matériaux et Télécommunication (INRS-EMT) Generation, characterization and applications of ultrashort laser pulses By Alborz Ehteshami A thesis submitted for the achievement of the degree of Master of Science, M.Sc in Energy and Materials Sciences Jury Members President of the jury François Vidal and Internal Examiner INRS-EMT External Examiner Feruz Ganikhanov University of Rhode Island Director of Research François Légaré INRS-EMT © Alborz Ehteshami, March 27, 2021 DEDICATION This thesis is dedicated to my beloved Parents & Siblings iii ACKNOWLEDGEMENTS It is my proud privilege to convey my sincere gratitude to my supervisor, Prof. François Légaré. I am grateful for the opportunity to have joined his team. I believe his patience and guidance eased my transition into this field. Moreover, his insightful feedback pushed me to sharpen my thinking and brought my work to a higher level. Throughout the writing of this dissertation, I have received a great deal of support and assistance from my good friend Arash Aghigh. I owe a debt of gratitude to him. Afterwards, I would like to thank Reza Safaei, who introduced me to INRS, and Légaré's team. Reza’s support continued throughout the entire duration of my study. I am also grateful to my friend and colleague Elissa Haddad for her support and assistance on the French interpretation. This master thesis has been carried out at National Institute of Scientific Research (INRS), and a number of people including the technical staff of the Advanced Laser Light Source (ALLS) deserve recognitions for their support and help.