University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2012 Laser Filamentation Interaction With Materials For Spectroscopic Applications Matthew Weidman University of Central Florida Part of the Electromagnetics and Photonics Commons, and the Optics Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (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 Weidman, Matthew, "Laser Filamentation Interaction With Materials For Spectroscopic Applications" (2012). Electronic Theses and Dissertations, 2004-2019. 2385. https://stars.library.ucf.edu/etd/2385 LASER FILAMENTATION INTERACTION WITH MATERIALS FOR SPECTROSCOPIC APPLICATIONS by MATTHEW R. WEIDMAN B.S. Oregon Institute of Technology, 2006 M.S. University of Central Florida, 2007 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Optics and Photonics at the University of Central Florida Orlando, Florida Fall Term 2012 Major Professor: Martin Richardson ©2012 Matthew R. Weidman ii ABSTRACT Laser filamentation is a non-diffracting propagation regime consisting of an intense core that is surrounded by an energy reservoir. For laser ablation based spectroscopy techniques such as Laser Induced Breakdown Spectroscopy (LIBS), laser filamentation enables the remote delivery of high power density laser radiation at long distances. This work shows a quasi- constant filament-induced mass ablation along a 35 m propagation distance. The mass ablated is sufficient for the application of laser filamentation as a sampling tool for plasma based spectroscopy techniques. Within the scope of this study, single-shot ablation was compared with multi-shot ablation. The dependence of ablated mass on the number of pulses was observed to have a quasi-linear dependence on the number of pulses, advantageous for applications such as spectroscopy. Sample metrology showed that both physical and optical material properties have significant effects on the filament-induced ablation behavior. A relatively slow filament-induced plasma expansion was observed, as compared with a focused beam. This suggests that less energy was transferred to the plasma during filament- induced ablation. The effects of the filament core and the energy reservoir on the filament- induced ablation and plasma formation were investigated. Goniometric measurements of the filament-induced plasma, along with radiometric calculations, provided the number of emitted photons from a specific atomic transition and sample material. This work advances the understanding of the effects of single filaments on the ablation of solid materials and the understanding of filament-induced plasma dynamics. It has lays the foundation for further quantitative studies of multiple filamentation. The implications of this iii work extend beyond spectroscopy and include any application of filamentation that involves the interaction with a solid material iv ACKNOWLEDGMENTS I would like to acknowledge the guidance and support of my advisor Dr. Martin Richardson without whom the research work presented here would not have been possible. I would also like to thank the members of my committee Dr. Demetrios Christodoulides, Dr. Axel Schülzgen, and Dr. Michael Sigman for their time and commitment throughout my candidacy, proposal and now dissertation. Beyond serving as my external committee member, Dr. Sigman played an active role in my spectroscopy related research. As a close collaborator and co-author, Dr. Sigman’s constant patience combined with his ability to clearly explain not only chemistry, yet also basic the educate in scientific writing was greatly appreciated—lessons that I hope will be reflected within this manuscript. The support, mentoring, guidance and friendship of Dr. Santiago Palanco (Sorry about your ankle Santi), as an impressionable young graduate student, helped me develop and grow as a scientist. Many of the experimental skills that I rely on today were developed working with Dr. Palanco. For his ever positive attitude and motivation, I owe Dr. Matthieu Baudelet a great debt. His enormous passion for spectroscopy might be inferred by the insane number of hours he spends in his office, yet if you’re lucky you might also catch him reading a scientific text book on the beach. After the completion of my M.S. degree, my decision to pursue a PhD and partial credit for my continued motivation and work ethic, that has brought me to the point of writing this dissertation, goes to Dr. Baudelet. v Conducting experiments with a commercially manufactured ‘turn-key’ femtosecond laser system was not without the occasional failure. In fact, the skills needed for the constant up keeping of this $500,000 system were not to be learned overnight. I cannot count the number of phone calls to Matt Fisher, the graduate student before me, in which he explained how to correct various problems. Likewise, Joe Juenemann from Spectra Physics was always prompt to reply to emails and phone calls and his experience was greatly appreciated. For their laser related expertise and assistance, I would also like to thank Michael Hammer, Andreas Vaupel, Ben Webb, Dr. Larry Shah, and Tony Teerawattanasook. For their assistance with sample preparation within the CREOL cleanrooms, I would like to thank, Casey Boutwell, Ming Wei, Matt Weed, Nathan Bickel, Jeremy Mares and Amitabh Ghoshal. For assistance with sample characterization I would like to thank Troy Anderson for teaching me how to use the white light interferometric microscope, as well as Mikhail Klimov and Kirk Scammon at the Advanced Materials Processing and Analysis Center (AMPAC). It has been a great pleasure to work with Dr. Bruno Bousquet, visiting professor from Bordeaux, France; Dr. Tony Valenzuela and Dr. Chase Munson researchers at the ARL and Dr. Paul Dagdigian at The Johns Hopkins University. Special thanks to the other members of Laser Plasma Laboratory, both past and present, especially, Mark Ramme for always being there for our 4PM coffee or hot chocolate, and the other members of our filamentation team: Khan Lim, Nick Barbieri, Erik McKee and Dr. Magali Durand. vi To my family—Janet, Peter, Katie, Robbie, Clara and Betsy, for always supporting me in my academic endeavors vii TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................................... xiii LIST OF TABLES ..................................................................................................................... xxiv LIST OF ACRONYMS .............................................................................................................. xxv CHAPTER 1. INTORDUCTION ................................................................................................... 1 1.1 Motivation ........................................................................................................................ 1 1.2 Organization of document ................................................................................................ 3 CHAPTER 2. FEMTOSECOND FILAMENTATION .................................................................. 4 2.1 Introduction ...................................................................................................................... 4 2.1.1 Historical development ............................................................................................. 7 2.2 Filamentation physics ....................................................................................................... 8 2.2.1 Kerr effect ................................................................................................................. 8 2.2.2 Critical power............................................................................................................ 9 2.2.3 Plasma defocusing .................................................................................................. 10 2.3 Characteristics of filaments ............................................................................................ 11 2.3.1 Filament plasma density ......................................................................................... 12 2.3.2 Energy contained within a filament ........................................................................ 16 2.3.3 Temporal profile of filaments ................................................................................. 17 2.3.4 Length of a filament ................................................................................................ 20 viii 2.4 Applications of filaments ............................................................................................... 21 2.4.1 White light continuum generation for LIDAR ........................................................ 21 2.4.2 Terahertz emission for spectroscopy ...................................................................... 22 2.4.3 Material processing ................................................................................................. 23 2.4.4 Guiding of electrical discharge ............................................................................... 24 2.4.5 Filament induced plasma spectroscopy .................................................................