High power high energy lasers have recently emerged as potential solution for several applications such as secondary rays generation, nuclear fusion and medical therapy. One major limitation of such systems for high energy extraction is the laser-induced damage threshold (LIDT) of laser components.
In this context, many studies have been devoted to the determination of the LIDT of laser materials under certain operational conditions and the identification of the limiting factors at the nanoseconds and femto/sub-picoseconds regime 1–3.However, these measurements do not consider that in most high intensity laser chains such as chirped pulsed amplification (CPA), pulses are stretched to larger duration such as hundreds of picoseconds. Thus, measuring the LIDT of laser materials under stretched pulses irradiation becomes critical.
In this work, we report a study of the influence of the coating treatment and fatigue in the LIDT of Yb:YAG crystals under stretched pulses by means of 1-on-1, Rasterscan and S-on-1 tests. We use a 1mJ, 1kHz laser (S-Pulse model from Amplitude Systèmes) modified to support 150 ps-pulse duration. We show a lower LIDT of the AR-coating compared to that of the HR-coating (7J/cm2) and preliminary outcomes point out a non-deterministic effect of the fatigue at this regime of pulse duration. These results show the importance of testing critical components at hundred-picoseconds regime for high power and high energy lasers.
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