Kenneth Schafer

Ball Family Distinguished Professor

Ph.D., 1989 - University of Arizona

Louisiana State University
Department of Physics & Astronomy
222-B Nicholson Hall, Tower Dr.
Baton Rouge, LA 70803-4001
225-578-0466-Office
schafer@phys.lsu.edu

Research Interests

Atomic, Molecular and Optical Physics

I am a theoretical AMO physicist who specializes in strong field physics. The name ``strong field physics'' refers to the interaction of intense, ultrafast laser pulses with atomic and molecular systems. Strong field physics takes place in the interesting regime where the electron-ion and electron-laser interactions are of competing strengths. This gives rise to a host of time-dependent and highly non- linear phenomenon such as above threshold ionization, high harmonic generation, sequential and non-sequential multiple ionization of atoms and molecules, and x-ray production from clusters, which are characterized both by rapid ionization and the coherent interaction of the ionizing electron with the parent atomic or molecular ion.

My current research centers on the theory of intense laser-matter interactions with an emphasis on the generation and application of attosecond pulses. An attosecond is 1/1000 of a femtosecond, and attosecond sources are the shortest light pulses ever made. Since attosecond pulses were first measured in 2001, the growth of "attoscience" has been exponential, spurred by the potential these pulses have for imaging and controlling electron motion. Our research group, consisting of myself and Mette Gaarde, has the unique capability to investigate all phases of the attosecond pulse generation process, from the microscopic single atom interaction to the macroscopic propagation and phase matching of the emitted radiation. The research is interdisciplinary, combining atomic and optical physics, and centered around high performance computing for non-perturbative solutions of both the time- dependent Schroedinger equation and the Maxwell wave equation. The research is highly relevant to experiment and we have active collaborations with several of the leading experimental groups pursuing attosecond science. We are involved in all phases of the experimental work, both as interpreters of results and as partners in designing new experiments.

Current and Select Publications

• D.C. Yost, T.R. Schibli, J. Ye, J.L. Tate, J. Hostetter, M.B. Gaarde and K.J. Schafer, "VUV frequency combs from below threshold harmonics,"Nature Phys., published online: 20 September 2009 | doi:10.1038/nphys1398.
• M.B. Gaarde, J.L. Tate, and K.J. Schafer, "Invited Topical Review: Macroscopic aspects of attosecond pulse generation," J. Phys. B: AMO 41, 132001 (2008).
• J. Mauritsson, J. Johnsson, E. Gustafsson, M. Swoboda, T. Ruchon, A. L'Huillier and K.J. Schafer, "Coherent Electron Scattering Captured by an Attosecond Quantum Stroboscope," Phys. Rev. Lett. 100, 073003 (2008).
• P. Johnsson, J. Mauritsson, T. Remetter,, A. L’Huillier , and K. J. Schafer, "Attosecond control of ionization dynamics by wavepacket interference," Phys. Rev. Lett. 99, 233001 (2007).
• M.B. Gaarde and K.J. Schafer, "Generating single attosecfond pulses via spatial filtering," Optics Lett. 31, 3188 (2006).
• T. Remetter, P. Johnsson, J. Mauritsson, J. Varjú, Y. Ni, F. Lépine, E. Gustafsson, M. Kling, J. Khan, R. López-Martens, K.J. Schafer, M.J.J. Vrakking and A. L'Huillier, "Attosecond electron wave packet interferometry," Nature Phys. 2, 323 (2006).
• P. Johnsson, R. López-Martens, S. Kazamias, J. Mauritsson, C. Valentin, T. Remetter, K. Varjú, M.B. Gaarde, Y. Mairesse, H. Wabnitz, P. Salieres, P. Balcou, K.J. Schafer and A. L'Huillier, "Attosecond electron dynamics in strong laser fields," Phys. Rev. Lett. 95, 013001 (2005).
• K.J. Schafer, M.G. Gaarde, A. Heinrich, J. Biegert and U. Keller, "Strong field quantum path control using attosecond pulse trains," Phys. Rev. Lett. 92, 023003 (2004).