Fig. 1. Photograph of large-size DKDP crystal grown by traditional method^[11]

Fig. 2. Cuboid DKDP crystal grown by rapid growth method^[55]. (a) Schematic diagram of crystal holder; (b) photograph of DKDP crystal

Fig. 3. Top and side views of LBO single crystal (weight is 1988 g, over size is 160 mm×150 mm×77 mm)^[68]. (a) Top view; (b) side view

Fig. 4. Photo of YCOB crystal from Shandong University^[17]. (a) 110 mm diameter YCOB single crystal; (b) 125 mm diameter YCOB single crystal

Fig. 5. As-grown LGN crystal with diameter of 60 mm using Czochralski method and its characteristics^[80]

Fig. 6. External angular acceptance for NCPM FHG of 1053 nm radiation in ADP and DKDP crystals^[99]

Fig. 7. External NCPM FHG conversion efficiency as a function of input 2ω energy^[99]

Fig. 8. NCPM FHG conversion efficiency as a function of input 2ω energy for ADP crystal with deuteration rate of 60%^[100]

Fig. 9. Energy (squares) and conversion efficiency (dots) of FHG as functions of energy of fundamental pump measured in LBO with crystal length of 10 mm^［109］

Fig. 10. Type-I SHG phase matching curves of YCOB crystal^[115]. (a) Phase matching curve in principal planes; (b) spatial phase matching curves for 1550‒1700 nm with interval of 30 nm

Fig. 11. Measured (solid dots) and calculated (smooth curves) output energy varying with tunable MIR wavelength for type I and type II DFG at constant pump energy of about 12 mJ and fluctuated signal energy of about 3 mJ (insets show fluctuated energy of input signal at different signal wavelengths)^[28]. (a) Type Ⅰ DFG; (b) type Ⅱ DFG

Fig. 12. Simulation results for type-I degenerate OPCPA pumped at 1.054 μm^{[27, 161]}. (a) Efficiency evolutions along crystal length of LGN and LiNbO₃; (b) temporal profiles of input pump or chirped signal pulses, residual pump pulses, and amplified chirped signal pulses in LGN and LiNbO₃; (c) spectra of input signal and amplified signals in LGN and LiNbO₃; (d) compressed pulses without and with OPP compensation in LGN and LiNbO₃-based OPCPAs

Fig. 13. Transparent regions and damage thresholds of commonly used nonlinear crystals^[29]