Fig. 1. Schematic diagram of stage development of strong-field THz pulse generation based on lithium niobate tilted pulse front technique

Fig. 2. Historical evolution diagram of tilted pulse front theoretical model. Green boxes represent relatively independent models, yellow boxes are supplements and improvements to the former, and red box represents the latest model. Dashed line indicates earlier theoretical models

Fig. 3. Critical factors affecting efficiency of THz generation

Fig. 4. Schematic of phase (velocity) matching of tilted pulse front laser and resulting THz wave. (a) Huyghens 　principle; (b) conservation of momentum^[36]

Fig. 5. Typical optical path diagram based on femtosecond laser pumping of lithium niobate crystals to generate single-period strong-field THz radiation

Fig. 6. Three methods for generating multi-period strong-field THz radiation based on tilted pulse front devices. (a) Chirp-delay technique; (b) burst technique; (c) echelon

Fig. 7. Method based on PPLN to generate multi-period strong-field THz radiation. (a) Schematic diagram of multi-period strong-field THz generation by PPLN; (b) phase-matching schematic; (c) phase-mismatching schematic; (d) quasi-phase-matching schematic

Fig. 8. Generation of strong-field THz radiation from lithium niobate crystals driven by femtosecond laser pulses and its applications

Fig. 9. Schematic diagram of the basic process of strong-field THz radiation on the interaction of electrons, spins, molecular vibration and rotation, and magnetons

Fig. 10. Schematic diagram of strong-field THz electron acceleration and manipulation and its applications

Fig. 11. Schematic diagram of biological effects of strong-field THz radiation at different scales

Fig. 12. Schematic diagram of important progress made by strong-field THz team of Beihang University in generation and application of strong sources