Construction of a 10-TW Laser of High Coherence and Stability and Its Application in Laser-Cluster Interaction and X-Ray Lasers
Date Issued
2005
Date
2005
Author(s)
Chu, Hsu-Hsin
DOI
en-US
Abstract
Following the progress of high-power laser systems advances in the past decade, the exploration of the interaction between strong electromagnetic field and matter has emerged as a new research frontier called “high-field physics”. The maximum intensity produced at the focus of an intense laser pulse can exceeds 10^20 W/cm^2, which is high enough to drive nonlinear motion of free electrons. Therefore, a new field of nonlinear optics, that of relativistic electrons, has been launched, and many applications such as laser-wakefield electron accelerators, soft x-ray lasers, high-order harmonic generation, and laser fusion are developed.
This thesis records my efforts and accomplishments in the research of high-field physics. Chapter 1 reviews the progress of high-power laser systems, including the mechanisms of femtosecond pulse generation and the principles of chirped-pulse amplification. Chapter 2 describes the construction of a versatile 10-TW laser system that I participated. How to achieve high stability and spatiotemporal quality by robust passive controls are presented, and the design principles and methods of characterization and verification are discussed. The basic physics of laser-plasma interaction is introduced in chapter 3, which provides the background knowledge of the following chapters. Chapter 4 presents the studies on the interaction between intense laser pulses and atomic clusters. Two experiments are described. The first is the maximization of soft x-ray emission form laser-irradiated argon clusters. The conversion efficiency in the 11–20 nm wavelength range reached 12%, and a pulse energy of as high as 0.3 mJ was obtained at 13.8-nm emission line. The brightness of this line emission reached 4.1 × 10^25 photons/cm^2/nm/sec/sr, close to that of synchrotron radiation at the same wavelength. This brightness was high enough for many soft x-ray applications such as x-ray microscopy and photolithography. The second is the control
of laser pulse propagation in a cluster gas, which was the first demonstration in the world. Transient refractive index of ionized cluster gas was verified, and the corresponding variations in the microscopic polarizability and macroscopic refractive index were observed. These unique properties may contribute to research on plasma nonlinear optics, such as phase matching of high-order harmonic generation and plasma waveguide formation. Finally,
chapter 5 presents the first demonstration of an optical-field-ionization (OFI) x-ray laser with a laser-irradiated xenon clustered gas jet. Near saturated amplification was achieved. The output energy reached 95 nJ, and the divergence angle of which was 5.2 mrad. In comparison with previous OFI x-ray lasers which use gas-cell targets, the use of gas jet make contamination-free and long-term operation possible.
The original works described in Chapter 2 and 4 are published in Appl.Phys.B 79, 193 (2004), Opt. Comm. 231, 375 (2004), and Phys. Rev.E 69, 035401(R) (2004). The x-ray laser work in Chapter 5 has been submitted to Phys. Rev. Lett. The international system of units (SI) are adopted for all formulas.
Subjects
X光雷射
雷射原子團交互作用
十兆瓦雷射
10-TW laser
laser-cluster interaction
x-ray laser
Type
thesis
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