###### Abstract  
Passive Q-switching is an effective approach for generating pulsed lasers, owing to its compact and additional modulation-free design. However, to compare favorably with active Q-switching and multi-stage amplification, the output energy needs to be enhanced for practical applications. Kramers Ytterbium ion (Yb\({}^{3+}\))-doped borate crystals, with their excellent energy storage capacity, have been proven to be high-potential laser gain mediums for achieving pulsed lasers with moderate and high output energy using passive Q-switching technology. In this study, the growth, characterization, and laser generation of one Yb\({}^{3+}\)-doped borate crystal, the Yb\({}^{3+}\)-ScBO\({}_{3}\) crystal, are systematically reviewed. The continuous-wave and passive Q-switching laser characteristics are presented in detail, and the self-pulsations derived from intrinsic ground-state reabsorption are also demonstrated. The specific characteristics and experiments confirm the potential of the Yb\({}^{3+}\)-ScBO\({}_{3}\) crystal for future pulsed laser applications with moderate or even high energy output.  
y tterbium-doped laser crystal; Czochralski crystal growth; solid-state lasers; passive Q-switching +
Footnote †: journal: Applied Sciences  
Yb\({}^{3+}\):Gd\({}_{3}\)Ga\({}_{5}\)O\({}_{12}\) (GGG) [20], (Yb\({}_{3}\)Y\({}_{1-x}\))\({}_{3}\)(Sc\({}_{1.5}\)Ga\({}_{0.5}\))Ga\({}_{3}\)O\({}_{12}\) (YSGG) [21], Yb\({}^{3+}\):Lu\({}_{3}\)Ga\({}_{5}\)O\({}_{12}\) (LuGG) [22], tungstates (e.g., Yb\({}^{3+}\):KGd(WO\({}_{4}\))\({}_{2}\) (KGW) [23; 24], Yb\({}^{3+}\):NaY(WO\({}_{4}\))\({}_{2}\) (NaYW) [25], Yb\({}^{3+}\):NaGd(WO\({}_{4}\))\({}_{2}\) (NaGdW) [26], Yb\({}^{3+}\):KLu(WO\({}_{4}\))\({}_{2}\) (KLuW) [27]), and borates (Yb\({}^{3+}\):YCa\({}_{4}\)O(BO\({}_{3}\))\({}_{3}\) (YCOB) [28; 29; 30], Yb\({}^{3+}\):GdCa\({}_{4}\)O(BO\({}_{3}\))\({}_{3}\) (GdCOB) [28; 31]). Among them, Yb\({}^{3+}\)-doped borates with short bond lengths (e.g., Yb:YCOB and Yb:GdCOB) have relatively smaller emission cross-sections (\(\sim\)0.5 \(\times\) 10\({}^{-20}\) cm\({}^{2}\)), longer fluorescence lifetimes (\(\sim\)2 ms), broader emission spectra (45 nm), and have been proven to be excellent energy storage materials. For example, a passive Q-switching laser with a pulse energy of 1.02 mJ was achieved in 2016, using GaAs as the saturable absorber [29].  
In 1993, the spectral characteristics of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal were reported, with an emission cross-section of \(\sim\)0.1 \(\times\) 10\({}^{-20}\) cm\({}^{2}\) and a fluorescence lifetime of \(\sim\)5 ms, indicating that it can be an ideal gain medium for obtaining Q-switching lasers with moderate or high pulse energy [32]. However, the growth difficulties of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal with its high optical quality have hindered further progress in laser applications. Most recently, the first optical grade Yb\({}^{3+}\):ScBO\({}_{3}\) crystal was successfully grown and both CW and passive Q-switching lasers have been realized [33; 34]. In addition, the growth method, characteristics, and laser performance of Yb\({}^{3+}\):ScBO\({}_{3}\) crystal has been systematically reviewed. The self-Q-switching characteristics derived from intrinsic ground-state reabsorption are also discussed. All results presented a high potential gain medium for moderate- or even high-energy pulsed laser generation using both active and passive Q-switching technologies.