Fig. 1. Experimental setup of tunable UV femtosecond OPO^[18]

Fig. 2. Experimental setup of tunable visible femtosecond OPO and results^[22]. (a) Experimental setup; (b) SFG power varying with wavelength; (c) visible light spectrum tuning of SFG from 610 to 668 nm

Fig. 3. Typical CSP-OPO pumped by laser and corresponding output wavelength range^[29]

Fig. 4. Schematic illustration of experimental setup for dielectric-mirror-less femtosecond OPO^[31]

Fig. 5. Schematic illustration of experimental setup for high-energy regenerative ps-OPO using intracavity pumping^[38]

Fig. 6. Experimental setup of chirped-pulse OPO based on SPM effect^[50]

Fig. 7. Output signal spectra with and without SPM effect^[50]

Fig. 8. Experimental setup of self-compressed femtosecond OPO^[34]

Fig. 9. Measured idler spectra and two-photon autocorrelation of self-compressed femtosecond OPO^[34]

Fig. 10. Principle of high repetition rate OPO using harmonic pumping^[60]. (a) Synchronous and harmonic pumping cavity; pulse sequences for (b) synchronous and (c) harmonic pumping

Fig. 11. Experimental setup of harmonically pumped GHz-OPO^[65]

Fig. 12. Experimental setup of high order Poincaré (HOP) beam OPO pumped by Yb-doped femtosecond fiber laser^[79]

Fig. 13. Experimental setup of two-channel dual beam mode OPO^[80]

Fig. 14. Output speckle patterns of different channels and corresponding lobe structure and interference speckle patterns of vortex beams^[80]

Fig. 15. Experimental setup of SHG stimulation of nano-tetrapod ZnO and experimental results^[89]

Fig. 16. Coherent Raman imaging system based on Yb laser system and Yb-laser pumped OPO ^[91]