Fig. 1. Setup of the grazing incidence MOPA laser system. Nd:YVO4 slab, a-cut slab; HWP, half-wave plate; LD, laser diode, the polarization is parallel to the c axis of the Nd:YVO4 slab; M1–M8, high reflectivity mirror; L1–L4, spherical lens, the focal length of L1 is 50 mm, L2 is 75 mm, L3 is 125 mm, and L4 is 75 mm; CL1–CL3, cylindrical lens.

Fig. 2. Output of the master oscillator. (a) The pulse duration, (b) the pulse repetition rate, (c) the output spectrum, and (d) the output beam profile.

Fig. 3. Schematic diagram of Nd:YVO4 slab and gain sheet. (a) 3D direction, (c) vertical direction, and (d) side view direction of Nd:YVO4 slab and copper heat sink; (b) the actual picture of the module.

Fig. 4. Design of the grazing incidence of Nd:YVO4 slab amplifier. (a) The injected beam is reshaped to beam width less than 200 µm by a CL on vertical axis, (b) the grazing angle of 6° can obtain 12.7 mm bounce width and 0.67 mm bounce depth, (c) the grazing angle of double pass.

Fig. 5. Output power versus pump power for the single pass and double pass amplification.

Fig. 6. Extraction efficiency ηE of the gain medium when light passes through it twice; the data of energy intensity on the horizontal axis are normalized to saturation fluence E_s.

Fig. 7. Output spectrum of the double pass amplification. (a) The output spectrum with 41 W pump power and (b) the output spectrum with 55 W pump power.

Fig. 8. Waveform of 7.37 W output for the double pass amplifier. (a) The pulse duration and (b) the pulse repetition rate.

Fig. 9. Output beam profile of the double pass amplifier.