The dual end-pumping configuration was applied in the experiments. The pump sources were two LD arrays, each with four bars and deliver an output peak power of 1200 W. The center wavelength was fixed at approximately 940 nm for Yb:YAG by maintaining the temperature of the cooling water at 23°C. The homogenization system of the pump light was the same as that utilized in Ref. [
]. The pumping peak power was 960 W after the homogenization system with 80% efficiency. A homogenous line pump light inside the Yb:YAG gain medium was obtained after the homogenization system. The dimensions of the pumping line were approximately 10 mm (
x) × 0.4 mm (
y). A quarter-wave plate with the Polarizer Rotation Mount (Beijing Huawei Haorun Instruments Co., Ltd) and a polarizer were set at the input end of the pulse amplifier, which was utilized to adjust the linear polarized input energy of a signal pulse laser. The input signal pulse laser originates from the LD pulse end-pumped
Q-switch Yb:YAG slab laser with a beam quality of
M2 = 1.55 in the slow axis and
M2 = 1.40 in the fast axis as shown in Ref. [
]. The input beam size of the amplifier was 0.49 mm in width (
x-direction). The input signal pulse laser was injected just after the end of the pump pulse light with a DG535 Digital Delay and Pulse Generator (Stanford Research System, Inc.). The output beam size of the amplifier after seven paths was folded in the Yb:YAG gain medium was 5.85 mm in width. The mirrors M1 and M6 were placed at 45° to guide the input and output beams of the pulse laser amplifier. The pulse energy of the amplifier in the experiments was measured by a LE-3B laser energy meter (Beijing Physcience Opto-Electronics Co., Ltd).