Collaborative Research: Exploring Plasma Dynamics of Femtosecond Laser-Induced Photoionization from Near to Mid-Infrared

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Recent progress in the development of laser sources enables generation of laser pulses at the high intensities, ultra-short pulse durations, and long wavelengths that could not be previously achieved. These novel lasers have potential for studying Earth's atmosphere as well as directed energy transmission over large distances. The central process enabling these unique applications is laser-induced generation of plasmas known as photoionization. Fundamental physical properties of photoionization at these extreme laser parameters are currently largely unknown. This project will advance the understanding of basic properties of photoionization and plasmas generated by these new types of lasers. The educational plan for this project aims to promote plasma science and other careers in science, technology, engineering, and mathematics. The research will be integrated into curricula by including results and demonstrations in several graduate-level courses on topics in plasma science and experimental methods. Outreach and education at the K-12 level will be accomplished by developing a cold plasma demonstration facility and a series of plasma science educational videos on YouTube. This project studies dynamics of plasmas generated by intense femtosecond laser pulses in the near and mid-infrared range. It will utilize elastic scattering of microwaves for absolute quantitative measurements of electron number density in a plasma in new, unexplored regimes. Specific research goals of the project include conducting thorough absolute measurements of electron number density and photoionization rates for an unprecedented wavelength range of intense laser pulses, from the near-ultraviolet to mid-infrared spectral range, and a broad range of intensities, gas types, and different polarization states. Another goal of the project is to conduct joint theoretical and experimental exploration of plasma generation by femtosecond laser gas ionization and subsequent plasma decay in various gaseous mixtures at atmospheric pressure in the presence of non-linear optical phenomena. The research program will significantly deepen our knowledge of femtosecond laser-induced gas ionization and subsequent plasma decay, the understanding of which is currently very limited.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.