MSE Colloquium: Dr. Enam Chowdhury, High and ultra-high intensity laser materials interaction

Research Associate Professor in Physics, The Ohio State University

All dates for this event occur in the past.

264 MacQuigg Labs
105 W Woodruff Ave
Columbus, OH 43210
United States

Abstract

Since the invention of the laser over 50 years ago, laser matter interaction has been a topic of intense interest both from fundamental science and applications point of view. On the one side, super intense lasers like the SCARLET 400 TW at OSU[1], [2], which I designed and led the construction effort, are used to explore relativistic laser plasma effects, ushering a new regime of compact particle accelerators; on the other side, high intensity lasers are used as the finest ‘scalpels’ of the universe to perform eye surgery, and opened pathways for surface engineering (e.g. super-hydrophobic surfaces) and machining not possible before. At the heart of these phenomena is the femtosecond laser induced damage (fs-LID) of solids [3], [4]. Although experimental, theoretical and computational efforts on this topic have been ongoing for over two decades, large gaps in fundamental understanding remain to this day. In Femtosecond Solid Dynamics program on laser damage at OSU, we are experimentally identify the gaps we believe to be the most crucial and we are developing tools to address them [5], [6], e.g. how is fs-LID affected by bandgap, photon energy, band structure, electron-lattice coupling, and using these understandings, is it feasible to predict macroscopic observations like crater geometry, from fundamental principles, without fitting parameters [7]? Our primary objective is to develop a comprehensive, fundamental understanding of intense field laser damage in the femtosecond regime by combining experimental, theoretical and computational efforts that will inform and be benchmarked against one another. This creates an exceptionally versatile platform for creating exotic, non-equilibrium, metastable states of matter.

On the second part of my talk, I’ll explore a high repetition rate ultra-high intensity program that I helped develop at the Extreme Light Lab at the Air Force Research Laboratory, Dayton, where we explore light matter interaction at relativistic fields with liquid targets. Although demonstrations of up to 4 GeV electrons and ~100 MeV protons have been achieved in the past, all of these are not feasible as future accelerators, due to their slow duty cycle (usually single shot, rarely 1 Hz). There are many challenges to increasing the duty cycle, where laser technology, target technology, damage to system, target alignment, high repetition rate sub-micron plasma diagnostics provides nearly insurmountable obstacles. In this program, we developed ways to accelerate MeV electrons and ions at kHz repetition rate [8], by developing a combination of suitable laser system, diagnostic system, target system and experimental data collection system capable of handling the high duty cycle. This platform allow us to explore material doping and modification with MeV particles in a tabletop setup.

References

[1]   P. L. Poole, C. Willis, R. L. Daskalova, K. M. George, S. Feister, S. Jiang, J. Snyder, J. Marketon, D. W. Schumacher, K. U. Akli, L. Van Woerkom, R. R. Freeman, and E. A. Chowdhury, “Experimental capabilities of 0.4 PW, 1 shot/min Scarlet laser facility for high energy density science,” Appl. Opt., vol. 55, no. 17, 2016.

[2]   P. Poole, S. Trendafilov, G. Shvets, D. Smith, and E. Chowdhury, “Femtosecond laser damage threshold of pulse compression gratings for petawatt scale laser systems,” Opt. Express, vol. 21, no. 22, pp. 26341–26351, 2013.

[3]   S. K. Sundaram and E. Mazur, “Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses.,” Nat. Mater., vol. 1, no. 4, pp. 217–224, 2002.

[4]   B. Stuart, M. Feit, S. Herman,  a. Rubenchik, B. Shore, and M. Perry, “Nanosecond-to-femtosecond laser-induced breakdown in dielectrics,” Phys. Rev. B, vol. 53, no. 4, pp. 1749–1761, 1996.

[5]   N. Talisa and E. A. Chowdhury, “Few cycle pulse laser ablation study of single layer TiO2 thin films using time resolved surface microscopy,” Opt. Express, vol. 26, no. 23, pp. 30371–30382, 2018.

[6]   D. R. Austin, K. R. P. Kafka, Y. H. Lai, Z. Wang, C. I. Blaga, and E. A. Chowdhury, “Femtosecond laser damage of germanium from near- to mid-IR wavelengths,” Opt. Lett., vol. 43, no. 15, pp. 3702–3705, 2018.

[7]   R. A. Mitchell, D. W. Schumacher, and E. A. Chowdhury, “Modeling crater formation in femtosecond-pulse laser damage from basic principles,” Opt. Lett., vol. 40, no. 10, 2015.

[8]   J. T. Morrison, S. Feister, K. D. Frische, D. R. Austin, G. K. Ngirmang, N. R. Murphy, C. Orban, E. A. Chowdhury, and W. M. Roquemore, “MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction,” New J. Phys. Fast Track Artic., vol. 20, no. 2, p. 22001, 2018.

Bio

 

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Dr. Enam Chowdhury

A leading expert in the field of high power short pulse lasers, ultra-intense and high energy density laser matter interaction, Research Associate Professor at OSU Physics, Dr. Enam Chowdhury currently leads Femtosecond Solid Dynamics Laboratory, a program dedicated to studying fundamentals of laser solid interactions near material damage threshold, including ionization, ablation, multi-pulse effects, laser induced periodic surface structures. He led the design and construction of the 400 TW SCARLET laser system at the Ohio State University, which is one of the most intense lasers operational in the world studying high energy density physics and its various applications, such as laser plasma based MeV electron and ion acceleration.  Dr. Chowdhury won many grants from various agencies, including AFOSR, DARPA, AFRL, ARL, NSF and DoE and authored over 50 articles in peer reviewed journals and conference proceedings in physics and engineering.