發(fā)布時間：2021-02-28 08:30

　　High-order harmonic generation（HHG）is a nonlinear process in which an intense infrared（IR）laser pulse interacts with gas medium.It has become an important tool for providing tabletop subfemtosecond or a few tens of attosecond light sources with great brightness and coherence from the extreme ultraviolet（XUV）to X-rays.However,the low conversion efficiency of HHG has limited its wide applications in science and technology.In this thesis,we investigate how to enhance the harmonic yields with the as... 

【文章來源】：南京理工大學江蘇省 211工程院校

【文章頁數(shù)】：79 頁

【學位級別】：碩士

【文章目錄】：
Abstract
1 Introduction to High-order Harmonic Generation
    1.1 Fundamentals of High-Order Harmonic Generation
        1.1.1 Brief History of Lasers
        1.1.2 Background to High-Order Harmonic Generation
        1.1.3 Generation of APT and SAP
        1.1.4 High-Harmonic Spectroscopy
    1.2 The Three-Step Model
        1.2.1 Ionization
        1.2.2 Propagation
        1.2.3 Recombination
    1.3 Phase Matching of High Harmonics in a Macroscopic Medium
    1.4 Multi-Color Manipulation of HHG
        1.4.1 Selection of Single Harmonics Using the Multi-Color Laser
        1.4.2 Enhancement of Harmonic Yield Using Two Commensurate Lasers
        1.4.3 XUV Light Amplification: XUV+IR
    1.5 Scope of This Work
2 Theoretical Models
    2.1 Introduction
    2.2 Time-Dependent Schrodinger Equation （TDSE）
        2.2.1 Introduction to the Semi-Classical Theory
        2.2.2 Time-Dependent Schrodinger Equation
    2.3 Strong-Field Approximation （SFA）
        2.3.1 General Formulation
        2.3.2 Derivation of the Lewenstein Model for the HHG
    2.4 Quantum Orbits Theory
    2.5 Quantitative Rescattering Model
        2.5.1 Formulation of the Quantitative Rescattering Model
        2.5.2 The Choice of Different Dipole Forms in the SFA
    2.6 Macroscopic Propagation of High-Harmonic Field
        2.6.1 Propagation of the Fundamental Laser Field
        2.6.2 Propagation of the High-Harmonic Field
        2.6.3 Phase-Matching Conditions
    2.7 Other Theoretical Tools
        2.7.1 Formulation of the Single-Atom HHG
        2.7.2 Wavelet Analysis
3 Comparison of One- and Two-Color Laser Fields for High Harmonic Generation
    3.1 Introduction
    3.2 Harmonic Generation Driven by an 800-nm Laser
    3.3 Combination of an 800-nm Laser with Its Second or Third Harmonic Fiel
        3.3.1 The Combination of 800+400 nm
        3.3.2 The Combination of 800+267 nm
    3.4 Combination of an IAP in the XUV with an 800-nm Laser
        3.4.1 Enhancement Factor of High Harmonic by Adding XUV pulse
        3.4.2 Time Frequency Analysis for XUV-Assisted Harmonic Emission
4 Harmonic Enhancement by Using XUV and Two-Color Laser Pulses
    4.1 Introduction
    4.2 Combination of an IAP in the XUV with the 800-nm and Its Second or ThirdHarmonic Field
        4.2.1 Typical HHG Spectra of the XUV Pulse with the 800- and 400-nmLasers
        4.2.2 Harmonic Enhancement Factor by Adding the XUV Pulse with the Two-Color （800+267 nm） Laser Fields
    4.3 Time Frequency Analysis for XUV-Assisted Harmonic Emission
        4.3.1 TFA by Varying the Time Delay between the Two-Color Waveform andXUV Pulse
        4.3.2 TFA by Varying the Relative Phase in the Two-Color Field
    4.4 Weak XUV with an Optimized Two-Color Waveform
    4.5 Macroscopic effect: Intensity averaging
    4.6 Retrieval of the Information of Input Attosecond Pulses
5 Summary and Outlook
Acknowledgements
References
Publications



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