## 3 Results and Discussion  
Figure 3a demonstrates the output power at 559 nm versus the incident pump power. The temperature of LBO crystal (\(\theta=90^{\circ}\) and \(\varphi=8^{\circ}\)) was maintained at 24 \({}^{\circ}\)C to obtain the optimal phase-matching. We measured the output power by a thermal power sensor (THORLABS S425C-L). For the self-Raman Nd:YVO\({}_{4}\) laser, the lasing threshold was approximately at 0.8 W and the output power was up to 6.54 W at the incident pump power of 40 W, with an optical conversion efficiency of 16.4%. In contrast to the self-Raman Nd:YVO\({}_{4}\) laser, the lasing threshold of Nd:YVO\({}_{4}\)/KGW Raman laser was measured near 3 W. The higher threshold reflects that inserting KGW crystal can lead to the insertion losses of laser cavity. However, the thermal lens issue can be simply solved by sharing the numerous thermal loading by the KGW crystal. Accordingly, the output power at 559 nm can be considerably improved to 9.1 W at the incident pump power of 40 W, and an optical conversion efficiency was calculated to 22.8%. At the pump power below 30 W, it was found that the overall output power in the self-Raman Nd:YVO\({}_{4}\) laser was higher than that  
Figure 1: Experimental setup of the diode-pumped (**a**) self-Raman Nd:YVO\({}_{4}\) lasers and (**b**) Nd:YVO\({}_{4}\)/KGW Raman lasers with intracavity SFG and SHG for accomplishing the lime and orange wavelengths. Figure 2: (**a**) The Reflectance spectrum of coating on the facet of KGW crystal toward the Nd:YVO\({}_{4}\) crystal; (**b**) The other facet of KGW crystal coating highly reflective at visible. in Nd:YVO4/KGW Raman laser as shown in Figure 3a. On the other hand, when the pump power reached 30 W, the growth of output power started to saturation in the self-Raman Nd:YVO4 laser, which was attributed to the strong thermal lens from the Nd:YVO4 crystal. Besides, due to the properties of KGW crystal such as anisotropic thermal expansion coefficients and negative thermal lens, the Nd:YVO4/KGW Raman laser is more suitable for operating at high pump power [25]. Figure 3b,c show the lasing spectrums and the transverse patterns of self-Raman Nd:YVO4 laser and Nd:YVO4/KGW Raman laser at the incident pump power of 10 W, respectively. The optical spectrum was monitored by an optical spectrum analyzer (Advantest Q8381A) with a resolution of 0.1 nm. The transverse pattern was imaged by a CCD camera at the distance \(z\approx 8z_{R}\) behind the beam waist, where \(z_{R}\) is Rayleigh length. The M2 factors were found to be approximately 3.0 \(\pm\) 0.5 for self-Raman Nd:YVO4 laser and Nd:YVO4/KGW Raman laser at 559 nm by utilizing laser beam diagnostics. In addition to the output performance of 559 nm, Figure 4a also shows the output power at 588 nm and 589 nm as the function of the incident pump power. The other LBO crystal (\(\theta\) = 90\({}^{\circ}\) and \(\varphi\) = 3.9\({}^{\circ}\)) was exploited here to accomplish SHG of the first Stokes field at the temperature of 22 \({}^{\circ}\)C. The lasing threshold of 588 nm was equal to that of 559 nm in the self-Raman Nd:YVO4 laser. The output power of 5.12 W at 588 nm was achieved at the incident pump power of 40 W. However, by using the Nd:YVO4/KGW Raman laser that we mentioned above, the output power of 7.5 W at 589 nm was obtained, with the lasing threshold at 2.2 W. At the pump power below 20 W, the overall output power in the self-Raman Nd:YVO4 laser was slightly higher than that in the Nd:YVO4/KGW Raman laser. Nevertheless, at high pump power regions, the self-Raman Nd:YVO4 laser also reflected the thermal loading in the saturation of output power. The corresponding optical conversion efficiency can be increased from 12.8% to 18.8%. The lasing spectrums and the transverse patterns were also shown in Figure 4b,c. The M2 factor for both lasers at 588 nm and 589 nm was estimated to 3.0 \(\pm\) 0.5.