Zenghu Chang

Organization: Professor, Canada Excellence Research Chair, University of Ottawa, Canada

Abstract title: Attosecond X-ray sources driven by long-wavelength lasers

Abstract resume:

Attosecond extreme ultraviolet sources based on high harmonic generation (HHG) driven by Ti:Sapphire lasers centered at 800 nm have been the workhorse for studying electron dynamics since 2001. However, the photon energy range with sufficient flux for time-resolved experiments is limited <130 eV. The three-step model predicted that the cutoff photon energy of HHG can be extended by increasing the driving laser wavelengths. In recently years, significant progress has been made in developing few-cycle, carrier-envelope phase stabilized, high peak-power lasers in the 1.6 to 2 micron that has laid the foundation for attosecond X-ray sources in the water window (282 – 533 eV), which covers the atomic K-shell excitation of carbon and oxygen. Breakthroughs in ultrafast long-wavelength light sources have been made in recent years. Chirped pulse amplifiers centered at 2.5 and 4.1 micron based on Cr:ZnSe and Fe:ZnSe have been developed.  In addition, mid-wave infrared chirped pulse optical parametric amplifiers pumped by 2-micron lasers with high conversion efficiency has been demonstrated. They are becoming powerful tools for studying wavelength scaling laws in strong-field atomic and molecular physics.

About the speaker:

Zenghu Chang graduated from Xi’an Jiaotong University with a bachelor’s degree in 1982. He earned a master’s and a doctorate at the Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, in 1985 and 1988 respectively. From 1991 to 1993, Chang visited the Rutherford Appleton Laboratory. He worked at the University of Michigan after 1996. Then joined the physics faculty at Kansas State University in 2001 and became the Ernest & Lillian Chapin Professor in 2009. He joined the University of Central Florida in 2010 where he was a University Trustee Chair, Pegasus and Distinguished Professor, as well as the founding director of the Institute for the Frontier of Attosecond Science and Technology. Starting in 2024, Chang became a Canada Excellence Research Chair at the University of Ottawa.  Chang is a fellow of the American Physical Society and Optical Society of America.