Theory of Nonlinear Propagation of High Harmonics Generated in a Gaseous Medium

ISBN-13: 9783319346106 / Angielski / Miękka / 2016 / 159 str.

Cheng Jin

Opis

Providing a software package that allows realistic, comparable simulations of high-order harmonics spectra, this volume offers the theoretical tools to study high-order harmonic generation (HHG) by intense ultrafast infrared lasers in both atoms and molecules.

Spis treści

Introduction to High-Order Harmonic Generation.- Background.- Single-Atom Response.- Macroscopic Propagation Effects.- Applications of High-Order Harmonic Generation.- Thesis Outline.- Theoretical Tools.- Introduction.- Time-Dependent Schrödinger Equation.- Maxwell’s Wave Equation.- Far-Field Harmonic Emission.- Medium Propagation Effects in High-Order Harmonic Generation of Ar.- Introduction.- Macroscopic HHG Spectra: QRS vs TDSE.- Macroscopic HHG Spectra: Theory vs Experiment.- Disappearance of Cooper Minimum in the HHG Spectra of Ar.- Macroscopic Wave Packet.- Wavelength Scaling of Harmonic Efficiency.- Conclusion.- Comparison of High-Order Harmonic Generation of Ar Using a Truncated Bessel or a Gaussian Beam.- Introduction.- Simulation of HHG Spectrum of Ar.- Phase Matching Conditions at the Low Gas Pressure.- Pressure Induced Phase Mismatch.- Conclusion.- Generation of an Isolated Attosecond Pulse in the Far Field by Spatial Filtering with an Intense Few-Cycle Mid-Infrared Laser.- Introduction.- Macroscopic HHG Spectra of Xe Using an 1825-nm Few-Cycle Laser.- Spatiotemporal Evolution of Fundamental Laser Field.- Time-Frequency Representation of High Harmonics.- Spectral and Spatial Filtering in Generation of Attosecond Pulses.- CEP Dependence of Isolated Attosecond Pulses.- Comparison Between QRS and SFA in Modeling Propagation Effects.- Conclusion.- Effects of Macroscopic Propagation and Multiple Molecular Orbitals on the High-Order Harmonic Generation of Aligned N2 and CO2 Molecules.- Introduction.- HOMO contribution in HHG of Random and Aligned N2 Molecules.- Intensity Dependence of Multiple Orbital Contributions in HHG of Aligned N2 Molecules.- Shape Resonance in Photoionization and Harmonic Generation of N2 Molecules.- Contributions of Multiple Molecular Orbital in HHG of Aligned CO2 Molecules.- Major Factors that Influence Positions of the Minima in the HHG Spectra of Aligned CO2 Molecules.- Conclusion.- Photoelectron Angular Distributions in Single-Photon Ionization of Aligned N2 and CO2 Molecules Using XUV Light.- Introduction.- Connection Between Photoionization and harmonic Generation.- Total Photoionization Yield from Aligned N2 and CO2 Molecules.- Photoelectron Angular Distributions (PADs) of Fixed-in-Space N2 Molecules in the Laboratory Frame.- PADs of Transiently Aligned N2 Molecules in the Laboratory Frame.- Photon Energy Dependence of PADs for Aligned N2 Molecules.- PADs of Transiently Aligned CO2 Molecules in the Laboratory Frame.- Conclusion.-Summary.

O autorze

Dr. Cheng Jin received his Ph.D. in Physics from Kansas State University in May 2012. He received the K-State Physics Meritorious Graduate Research Award for 2011-2012, and received recognition for significant contributions to knowledge base by K-State’s Graduate Student Council in 2010.

Blurb

Theory of Nonlinear Propagation of High Harmonics Generated in a Gaseous Medium establishes the theoretical tools to study High-Order Harmonic Generation (HHG) by intense ultrafast infrared lasers in atoms and molecules. The macroscopic propagation of both laser and high-harmonic fields is taken into account by solving Maxwell's wave equations, while the single-atom or single-molecule response is treated with a quantitative rescattering theory by solving the time-dependent Schrödinger equation.

This book demonstrates for the first time that observed experimental HHG spectra of atoms and molecules can be accurately reproduced theoretically when precise experimental conditions are known. The macroscopic HHG can be expressed as a product of a macroscopic wave packet and a photorecombination cross section, where the former depends on laser and experimental conditions while the latter is the property of target atoms or molecules. The factorization makes it possible to retrieve microscopically atomic or molecular structure information from the measured macroscopic HHG spectra.

This book also investigates other important issues about HHG, such as contributions from multiple molecular orbitals, the minimum in the HHG spectrum, the spatial mode of laser beams, and the generation of an isolated attosecond pulse. Additionally, this book presents the photoelectron angular distribution of aligned molecules ionized by the HHG light.