Differentiating Between Different Nonlinear Excitation Terahertz Pathways Through the Use of Two-Dimensional Spectroscopy

ORAL

Abstract

Intense, short pulses of terahertz (THz) radiation has made it possible to study and manipulate the properties of materials on ultrafast (\textless 1 ps) time scales. As with any region of the electromagnetic spectrum, intense terahertz pulses can induce nonlinear excitation pathways. In order to understand how THz pulses can be used to manipulate structure in solids, it is of great interest to understand the process or processes that cause this type of nonlinear behavior. In this work, Raman-active modes in a CdWO$_{\mathrm{4}}$ crystal are nonlinearly excited. With single-pulse (one-dimensional) THz measurements, we cannot distinguish between nonlinear photonic (two-photon absorption) and nonlinear phononic (anharmonic coupling between vibrational modes) processes. We show that two-dimensional (2D) spectroscopy allows us to identify the main nonlinear excitation pathway (two-photon absorption), and by making slight (but significant) changes to the experimental setup, we can isolate the secondary excitation pathway (anharmonic coupling). The nonlinear phononic (anharmonic coupling) pathway has been posited with theoretical work, but never before experimentally confirmed.

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Authors

  • Aldair Alejandro

    Brigham Young University

  • John Spence

    Brigham Young University, Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, Department of Scientific Research, The Metropolitan Museum of Art, New York, NY 10028, Century Darkroom, Toronto, ON M4M 2S1, Canada, Colorado State University, University of Waterloo, Southern Connecticut State University, Clemson University, Oak Ridge National Laboratory, University of Bordeaux, BYU REU Program, New Mexico State University, Arizona State University, Biodesign Institute, Center for Applied Structural Discovery, University of Utah, University of Hawaii, Johns Hopkins University, Embry-Riddle Aeronautical University, Arizona State University, Utah State University, Department of Physics, United States Air Force Academy, Department of Chemistry, Case Western Reserve University, Air Force Research Laboratory, Wright-Patterson Air Force Base, United States Air Force Academy, Lousiana State University, Brigham Young University - Provo, The University of New Mexico, Department of Physics and Astronomy, Brigham Young University, SLAC National Accelerator Laboratory, Department of Chemistry, Brigham Young University, Department of Materials, Devices, and Energy Technologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA, Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA, Center for Memory and Recording research, UCSD, Advanced Photon Source, Argonne National Laboratory, University of New Mexico, Los Alamos National Laboratory, University of Chicago

  • John Spence

    Brigham Young University, Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, Department of Scientific Research, The Metropolitan Museum of Art, New York, NY 10028, Century Darkroom, Toronto, ON M4M 2S1, Canada, Colorado State University, University of Waterloo, Southern Connecticut State University, Clemson University, Oak Ridge National Laboratory, University of Bordeaux, BYU REU Program, New Mexico State University, Arizona State University, Biodesign Institute, Center for Applied Structural Discovery, University of Utah, University of Hawaii, Johns Hopkins University, Embry-Riddle Aeronautical University, Arizona State University, Utah State University, Department of Physics, United States Air Force Academy, Department of Chemistry, Case Western Reserve University, Air Force Research Laboratory, Wright-Patterson Air Force Base, United States Air Force Academy, Lousiana State University, Brigham Young University - Provo, The University of New Mexico, Department of Physics and Astronomy, Brigham Young University, SLAC National Accelerator Laboratory, Department of Chemistry, Brigham Young University, Department of Materials, Devices, and Energy Technologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA, Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA, Center for Memory and Recording research, UCSD, Advanced Photon Source, Argonne National Laboratory, University of New Mexico, Los Alamos National Laboratory, University of Chicago

  • John Spence

    Brigham Young University, Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, Department of Scientific Research, The Metropolitan Museum of Art, New York, NY 10028, Century Darkroom, Toronto, ON M4M 2S1, Canada, Colorado State University, University of Waterloo, Southern Connecticut State University, Clemson University, Oak Ridge National Laboratory, University of Bordeaux, BYU REU Program, New Mexico State University, Arizona State University, Biodesign Institute, Center for Applied Structural Discovery, University of Utah, University of Hawaii, Johns Hopkins University, Embry-Riddle Aeronautical University, Arizona State University, Utah State University, Department of Physics, United States Air Force Academy, Department of Chemistry, Case Western Reserve University, Air Force Research Laboratory, Wright-Patterson Air Force Base, United States Air Force Academy, Lousiana State University, Brigham Young University - Provo, The University of New Mexico, Department of Physics and Astronomy, Brigham Young University, SLAC National Accelerator Laboratory, Department of Chemistry, Brigham Young University, Department of Materials, Devices, and Energy Technologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA, Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA, Center for Memory and Recording research, UCSD, Advanced Photon Source, Argonne National Laboratory, University of New Mexico, Los Alamos National Laboratory, University of Chicago

  • John Spence

    Brigham Young University, Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, Department of Scientific Research, The Metropolitan Museum of Art, New York, NY 10028, Century Darkroom, Toronto, ON M4M 2S1, Canada, Colorado State University, University of Waterloo, Southern Connecticut State University, Clemson University, Oak Ridge National Laboratory, University of Bordeaux, BYU REU Program, New Mexico State University, Arizona State University, Biodesign Institute, Center for Applied Structural Discovery, University of Utah, University of Hawaii, Johns Hopkins University, Embry-Riddle Aeronautical University, Arizona State University, Utah State University, Department of Physics, United States Air Force Academy, Department of Chemistry, Case Western Reserve University, Air Force Research Laboratory, Wright-Patterson Air Force Base, United States Air Force Academy, Lousiana State University, Brigham Young University - Provo, The University of New Mexico, Department of Physics and Astronomy, Brigham Young University, SLAC National Accelerator Laboratory, Department of Chemistry, Brigham Young University, Department of Materials, Devices, and Energy Technologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA, Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA, Center for Memory and Recording research, UCSD, Advanced Photon Source, Argonne National Laboratory, University of New Mexico, Los Alamos National Laboratory, University of Chicago

  • John Spence

    Brigham Young University, Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, Department of Scientific Research, The Metropolitan Museum of Art, New York, NY 10028, Century Darkroom, Toronto, ON M4M 2S1, Canada, Colorado State University, University of Waterloo, Southern Connecticut State University, Clemson University, Oak Ridge National Laboratory, University of Bordeaux, BYU REU Program, New Mexico State University, Arizona State University, Biodesign Institute, Center for Applied Structural Discovery, University of Utah, University of Hawaii, Johns Hopkins University, Embry-Riddle Aeronautical University, Arizona State University, Utah State University, Department of Physics, United States Air Force Academy, Department of Chemistry, Case Western Reserve University, Air Force Research Laboratory, Wright-Patterson Air Force Base, United States Air Force Academy, Lousiana State University, Brigham Young University - Provo, The University of New Mexico, Department of Physics and Astronomy, Brigham Young University, SLAC National Accelerator Laboratory, Department of Chemistry, Brigham Young University, Department of Materials, Devices, and Energy Technologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA, Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003, USA, Center for Memory and Recording research, UCSD, Advanced Photon Source, Argonne National Laboratory, University of New Mexico, Los Alamos National Laboratory, University of Chicago