Fig. 1. Schematics of the experimental setup for (a) the CW Cr:ZnSe bulk crystal laser and (b) the tunable Cr:ZnSe bulk crystal laser. L1, collimating lens; L2 and L3, focus lenses; M1, M2, and M4, input mirrors; Tm:YLF and Cr:ZnSe, bulk laser crystal; OC1 and OC2, output couplers; DM1 and DM2, dichroic mirrors; M3, M4, and M5, folded mirrors.

Fig. 2. (a) Pump light spectra for the Cr:ZnSe bulk crystal. (b) Absorption efficiency of the Cr:ZnSe bulk crystal for the 1845 nm and 1887 nm pump light.

Fig. 3. Input-output curve of the Cr:ZnSe bulk crystal laser pumped by the 1845 nm pump light. (a) T_OC2 of 5% is used and (b) T_OC2 of 8% is used, respectively.

Fig. 4. Input-output curve of the Cr:ZnSe bulk crystal laser pumped by the 1887 nm pump light. (a) T_OC2 of 5% is used and (b) T_OC2 of 8% is used, respectively.

Fig. 5. Power stability of the Cr:ZnSe laser at the maximum output power.

Fig. 6. Laser spectra of the Cr:ZnSe bulk crystal laser in the CW operation. (a) For the 1845 nm pump and T_OC2 of 5%. (b) For the 1845 nm pump and T_OC2 of 8%. (c) For the 1887 nm pump and T_OC2 of 5%. (d) For the 1887 nm pump and T_OC2 of 8%.

Fig. 7. M²-factor of the Cr:ZnSe bulk crystal lasers measured in the fundamental mode operation. (a) For the 1845 nm pump and T_OC2 of 8%. (b) For the 1887 nm pump and T_OC2 of 8%.

Fig. 8. Higher-order mode generated at high incident pump power.

Fig. 9. (a) Tuning curves of the output power and (b) the corresponding spectra (T_OC = 8%) with the 1887 nm pump. The transmission curves of the mirrors used in the experiment are also presented in (b).

Fig. 10. (a) Tuning curves of the output power and (b) the corresponding spectra (T_OC = 5%) with the 1845 nm pump. The transmission curves of the mirrors used in the experiment are also presented in (b).