Propagation of a high-intensity laser pulse with small-scale intensity modulation

Abstract

For laser beams of large aperture with power far above the critical power for self-focusing, nonlinear propagation instabilities lead to the growth of small-scale variations in intensity and phase. We report measurements of the growth rate for interference fringes in unpumped ED-2 laser glass as a function of fringe spacing and intensity. Calculations based on the simplest form of linearized small-scale instability theory agree approximately with the measured rates, and a more complete linearized treatment predicts the growth rates within experimental error.

Spectral evolution of an optical pattern generated by spatial modulation instability in a reorientational Kerr nonlinear medium

“…In addition, the nonlinear growth is accompanied by energy transfer between different frequencies during nonlinear propagation in such a nonlinear medium owing to its non-instantaneous response to the applied field [13]. Besides, Equation (15) also shows that the gain coefficient decreases and the cutoff frequency disappears due to the presence of non-instantaneous …”

“…A simple linearized theory of spatial MI applicable to a single nonlinear medium was first derived by Bespalov and Talanov [7] (also known as B-T theory) and later verified experimentally by Campillo et al [14] and by Bliss et al [15]. The classical B-T theory gives a relatively simple and explicit explanation about spatial MI, providing an expression for the growth rate of frequency component, the fastest growth frequency and the maximum growth coefficient B (B integral).…”

The spatial and temporal evolution of the broadband chirped pulse with small-scale self-focusing

“…The growth of SSSF and phase irregularities on an intense laser pulse propagating in an optically nonlinear medium is predicted by Bespalov and Talanov [3] in 1960s, and soon was well verified by several early experimental studies [4][5][6][7][8][9][10]. These early studies of SSSF provided experimental conformation for the optical Kerr effect and served as an interesting complement to the companion process of large-scale or whole-beam self-focusing [11].…”

Beam modulation caused by the plasma scalds in the multilayer dielectric films

“…As a special case in the high-power laser facility such as SG-III in China [8], the beam modulated by the defects or structures on the surface of the optics may be harmful to the downstream optical components [9][10][11][12]. Multilayer dielectric films, widely used as a basic component such as the broadband pulse compression grating [13] and transport mirror [14,15], are generally processed by laser conditioning to improve the damage threshold [16] by eliminating the most dangerous precursors.…”