Fig. 1. CW experiment device of single blue LD pumped Pr:YLF laser. (a) Experimental configuration; (b) schematic diagram.

Fig. 2. Results of CW lasers. (a) Output power versus absorbed pump power for 638.1 nm red laser; (b) spectrum of the red output laser; (c) output power versus absorbed pump power for 721.1 nm deep red laser; (d) spectrum of the deep red output laser.

Fig. 3. Optical characterizations of prepared monolayer graphene and Co:ZnO epitaxial thin film. (a) Transmission spectra of monolayer graphene/sapphire and sapphire substrate (inset: picture of prepared monolayer graphene sample); (b) transmission spectra of 16% Co:ZnO and pure ZnO (inset: picture of prepared Co:ZnO sample); (c) trend of transmittance with the incident fluence for monolayer graphene at 532 nm; (d) trend of transmittance with the incident fluence for Co:ZnO at 532 nm.

Fig. 4. Characterizations of the $Q$-switched pulse lasers with monolayer graphene as the $Q$-switcher at 638 nm. (a) Average output power versus absorbed pump power; (b) repetition rate and pulse width of the pulse laser versus absorbed pump power; (c) pulse train recorded by the oscilloscope; (d) single red pulse with the pulse width of 709 ns.

Fig. 5. Characterizations of the $Q$-switched pulse lasers with Co:ZnO as the $Q$-switcher at 721 nm. (a) Average output power versus absorbed pump power; (b) repetition rate and pulse width of the pulse laser versus absorbed pump power; (c) pulse train recorded by the oscilloscope; (d) single deep red pulse with the pulse width of 586 ns.