Terahertz (THz) radiation with frequencies between 100 GHz and 30 THz has developed into an important tool of science and technology, with numerous applications in materials characterization, imaging, sensor technologies, and telecommunications. Recent progress in THz generation has provided ultrashort THz pulses with electric field amplitudes of up to several megavolts/cm. This development opens the new research field of nonlinear THz spectroscopy in which strong light-matter interactions are exploited to induce quantum excitations and/or charge transport and follow their nonequilibrium dynamics in time-resolved experiments. This book introduces methods of THz generation and nonlinear THz spectroscopy in a tutorial way, discusses the relevant theoretical concepts, and presents prototypical, experimental, and theoretical results in condensed matter physics. The potential of nonlinear THz spectroscopy is illustrated by recent research, including an overview of the relevant literature.
Author(s): Thomas Elsaesser, Klaus Reimann, Michael Woerner
Series: IOP Concise Physics
Publisher: IOP Publishing
Year: 2019
Language: English
Pages: 160
City: Bristol
PRELIMS.pdf
Author biographies
Thomas Elsaesser
Klaus Reimann
Michael Woerner
Symbols
CH001.pdf
Chapter 1 Introduction
1.1 Linear optical response
1.2 Low-energy excitations in condensed matter
1.2.1 Electronic excitations
1.2.2 Vibrational excitations
1.3 Charge transport in solids
References
CH002.pdf
Chapter 2 Terahertz technology
2.1 Generation of coherent terahertz radiation
2.1.1 Terahertz lasers
2.1.2 THz generation by optical frequency conversion
2.1.3 Photoconductive switches
2.2 Phase-resolved detection of terahertz transients
2.2.1 Photoconductive antennas
2.2.2 Electro-optic sampling
2.3 Linear terahertz spectroscopy and imaging
References
CH003.pdf
Chapter 3 Nonlinear light–matter interactions
3.1 Nonlinear optical response in the THz range
3.1.1 Theoretical framework
3.1.2 Approximations
3.2 Nonlinear currents in condensed matter
3.2.1 Shift currents in systems lacking inversion symmetry
3.2.2 Nonlinear currents of electrons in a periodic potential
3.2.3 Nonlinear currents without real-space transfer of carriers
3.3 Quantum coherences in coupled multi-level systems
3.4 Nonperturbative regime of light–matter interaction
References
CH004.pdf
Chapter 4 Methods of nonlinear terahertz spectroscopy
4.1 Concepts and experimental implementation
4.1.1 Optical geometries for nonlinear THz experiments
4.1.2 Interaction schemes and pulse sequences
4.2 Two-dimensional spectroscopy
4.2.1 Experimental methods of two-dimensional THz spectroscopy
4.2.2 Data representation and analysis
References
CH005.pdf
Chapter 5 Nonlinear terahertz spectroscopy of condensed matter
5.1 Dynamics and couplings of low-energy excitations in liquids and solids
5.1.1 Condensed-phase molecular systems
5.1.2 Solids and nanostructures
5.2 Field-driven nonlinear response and charge transport in solids
5.2.1 Nonlinear THz response of softmodes in a molecular crystal
5.2.2 Polaron transport
5.2.3 Coherent high-field transport in GaAs on femtosecond time scales
5.2.4 THz-induced interband tunneling of carriers
5.2.5 Shift current in LiNbO3
5.2.6 Nonlinear transport in graphene
5.3 Conclusions and outlook
References
