Abstract
Abstract The work presented in this paper is a study of output temporal contrast degradation by near-field quality deterioration, such as intensity modulation and wavefront deviation, in a large aperture high power short pulse laser system. A two-step focusing algorithm with a coordinate transform based on the Fresnel approximation in the space domain is used for simulating the output focused by an off-axis parabolic mirror. The temporal contrast degradation by intensity modulation and wavefront deviation is analyzed and the influence of the diameter on the temporal contrast degradation is revealed. The simulation and assumption results based on the parameters of the Shen Guang-II laser system are compared with the online experimental temporal contrast data. The near-field quality deterioration might lead to temporal contrast degradation, hindering higher temporal contrast in large aperture high power short pulse laser systems.
Highlights
With the development of chirped-pulse amplification (CPA) and optical parametric CPA (OPCPA), extremely intense short pulse laser systems are increasingly applied to experimental investigations in ‘fast ignition’ inertial confinement fusion (ICF), laser–plasma interactions and strong field physics[1]
In large aperture high power short pulse laser systems, the output is focused by an off-axis parabolic mirror (OAP), and this focusing propagation can be well simulated by a two-step coordinate transformed focusing method, taking advantage of using coordinate transformation and avoiding the contradiction between the space scale and the diffraction limit[13]
A two-step coordinate transformed focusing method is used to simulate the output focused by an OAP in a large aperture high power short pulse laser system, and the output temporal contrast is calculated
Summary
With the development of chirped-pulse amplification (CPA) and optical parametric CPA (OPCPA), extremely intense short pulse laser systems are increasingly applied to experimental investigations in ‘fast ignition’ inertial confinement fusion (ICF), laser–plasma interactions and strong field physics[1]. In large aperture high power short pulse laser systems, the output is focused by an off-axis parabolic mirror (OAP), and this focusing propagation can be well simulated by a two-step coordinate transformed focusing method, taking advantage of using coordinate transformation and avoiding the contradiction between the space scale and the diffraction limit[13]. Using this method, this paper simulates the output temporal contrast of a large aperture high power short pulse laser system.
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