Fig. 1. Overview of power climb in intense laser technology. (a) Power milestone for ultra-intense ultra-short lasers and high-energy continuous wave lasers; (b) mechanism of chirped-pulse amplification (CPA); (c) mechanism of spectral beam combining (SBC)

Fig. 2. Performance indicators of reflection pulse compression gratings for different high-power laser systems

Fig. 3. Classification of diffraction gratings commonly used in high-power laser system

Fig. 4. Main manufacturing process for reflection pulse compression grating

Fig. 5. Numerical simulation of groove profile of gold grating. (a) Common functions such as sine, gauss, moth-eye; (b) image to curve; (c) characteristic profile function

Fig. 6. Two numerical methods of gold grating

Fig. 7. Current status of gold grating aperture research at home and abroad

Fig. 8. Relationship between diffraction efficiency of gold grating and polarization of TM and TE, and relationship between diffraction efficiency of gold grating and groove depth at different linear densities. (a)‒(b) Relationship between diffraction efficiency of gold grating and polarization of TM and TE; (c)‒(d) relationship between diffraction efficiency of gold grating and groove depth at different linear densities^[48]

Fig. 9. 400 nm ultra-broadband gold grating^[58]. (a) Measured -1 order diffraction efficiency of 1443 g/mm at 50° (red line) and 1527 g/mm (blue line) at 62°, both with TM polarization, and an ultra-broadband gold grating is shown in the inset pictures; (b) grating profiles are measured by atomic force microscope (AFM) and focused ion beam-scanning electron microscope (FIB-SEM); (c) scanning photometric diffraction efficiency map at 950 nm

Fig. 10. Threshold rule of gold film and gold grating under 1053 nm pulsed laser radiation^[48]

Fig. 11. Non-conformal shape of gold gratings induce Joule heating^[51]

Fig. 12. Typical damage morphologies of gold gratings fabricated by e-beam evaporation and magnetron sputtering.^[55] (a) E-beam evaporation; (b) magnetron sputtering

Fig. 13. Pulse-width dependence of LIDT of a 1480 g/mm gold grating with a gold thickness of 200 nm, test wavelength is 1053 nm, and test angle is 52°^[60]

Fig. 14. Typical damage morphologies of gold gratings with (a) pulse width of 60 fs and (b) pulse width of 450 ps

Fig. 15. Damage-test table in the front end for the station of extreme light (SEL)^[58]. (a) Damage test platform layout; (b) measured and FTL pulse duration of the compressed laser pulse in S₁; (c) measured spectrum in S₁ and S₂; (d) measured beam spot in S₂

Fig. 16. Changes in height, LIDT, and morphology of gold gratings with the number of pulses. (a) Change in the height of the blister with number of pulses; (b) evolution of LIDT versus number of pulses; (c)‒(i) SEM images of blisters with different numbers of pulses near the LIDT; (j) a FIB cross-section picture of figure (d)

Fig. 17. Damage probability curve (red line and solid diamond) and temperature rise (circle) at 100 kHz repetition frequency^[65]. Color of circles represents different irradiation time, and values in color circles are measured temperature rise

Fig. 18. Mixed metal grating photographs and 1-on-1 damage threshold. (a) Photographs of mixed metal grating; (b) 1-on-1 damage threshold

Fig. 19. Domestic and foreign representative of high-quality SBC grating products

Fig. 20. Representative grating ridge structure of domestic SBC grating

Fig. 21. Thermal response detection of SBC grating, including temperature rise test, diffracted light far-field beam quality, and grating surface thermal distortion. The pump light is a high-energy beam laser, and the probe laser is used to form interference fringes based on Michelson interferometry for real-time detection of grating surface aberrations

Fig. 22. Evolution mechanism from temperature rise and thermal distortion to catastrophic damage of a SBC grating. (a) Temperature rise; (b) thermal stress damage; (c) blister; (d) wavefront distortion; (e) beam quality degradation; (f) catastrophic damage

Fig. 23. Influence of different cleaning processes on elemental content, diffraction efficiency, surface roughness, and temperature rise performance of spectral beam combining gratings. (a) Elemental content; (b) surface roughness; (c) diffraction efficiency; (d) temperature rise performance