## 3 Conclusions  
The growth, structure, physical characteristics, and laser performance of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal with an excellent energy storage capacity are comprehensively reviewed, for both CW and passive Q-switching laser characteristics. After partially overcoming difficulties, such as the intense volatilization of B\({}_{2}\)O\({}_{3}\), a bulk crystal was triumphantly grown using the Czochralski technique. However, the optical quality is still required to be improved since there are lots of inclusions, as presented above, although the Czochralski method has been proved to be feasible. The thermal properties of the Yb\({}^{3+}\):ScBO\({}_{3}\) crystal, consisting og thermal conductivity and specific heat and so on, were characterized. In addition, the Yb\({}^{3+}\):ScBO\({}_{3}\) crystal was found to possess a small emission cross-section of 0.12 \(\times\) 10\({}^{-20}\) cm\({}^{2}\) and a long fluorescence lifetime of 5.2 ms, which is beneficial for generating moderate and high-energy pulsed lasers. A CW laser, with a maximal output power of 167 mW and a slope efficiency of 9% under the wavelength of 1.063 \(\upmu\)m, was first obtained in the Yb\({}^{3+}\):ScBO\({}_{3}\) crystal, utilizing a plane-concave cavity configuration. Then, a passive Q-switching laser in this crystal was achieved utilizing BP as the optical modulator, with a minimum pulse width of 495.5 ns and a maximal pulse energy of 1.4 \(\upmu\)J. The consequences show the feasibility of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal achieving pulsed lasers with moderate or high energy. Finally, the self-Q-switching and nonlinear optical characteristics of this crystal were evaluated and the mechanism was attributed to ground state re-absorption. The preferable spectroscopic characteristics and preliminary laser performances indicate that the as-grown Yb\({}^{3+}\):ScBO\({}_{3}\) crystal would be a high-potential laser gain medium in establishing compact pulsed laser systems with moderate or even high energy output. Future research will be dedicated to the optimization of the crystal growth in the aspects of establishing the thermal field with small gradient and searching for the optimal growth parameters, including pulling and rotation rates, etc. In the meantime, the actively Q-switched pulsed lasers with high energy output are also expected in the Yb\({}^{3+}\):ScBO\({}_{3}\) crystal.  
**Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/app112210879/s1](https://www.mdpi.com/article/10.3390/app112210879/s1)]([https://www.mdpi.com/article/10.3390/app112210879/s1](https://www.mdpi.com/article/10.3390/app112210879/s1)), Table S1. Passively Q-switching performance and corresponding spectral and thermal properties in commonly used Yb\({}^{3+}\)-doped crystals.  
Figure 12: The transmittance versus input energy intensity of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal.  
**Author Contributions:** Conceptualization, H.Y., H.Z. and J.W.; Data collection, X.L. and D.L.; writing--original draft preparation, X.L. and D.L.; writing--review and editing, D.L. and H.Y.; supervision, H.Y., H.Z. and J.W. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (NSFC) (Grant 51902181) and Future Plans of Young Scholars at Shandong University.  
Not applicable.  
**Data Availability Statement:** All the data reported in the paper are not publicly available at this time but maybe provided upon reasonable request.  
The authors declare no competing financial interest.