Dopant site | $({\mathrm{T}\mathrm{i}}_{x}{\mathrm{A}\mathrm{l}}_{1-x}{)}_{2}{\mathrm{O}}_{3}$ | $\mathrm{B}\mathrm{e}({\mathrm{A}\mathrm{l}}_{1-x}{\mathrm{C}\mathrm{r}}_{x}{)}_{2}{\mathrm{O}}_{4}$ | $({\mathrm{Y}\mathrm{b}}_{x}{\mathrm{Y}}_{1-x}{)}_{3}{\mathrm{A}\mathrm{l}}_{5}{\mathrm{O}}_{12}$ |

Dopant density at 1% doping [${\times 10}^{20}\phantom{\rule{thickmathspace}{0ex}}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{s}/{\mathrm{c}\mathrm{m}}^{3}$] | 4.7 [45] | 3.51 [48] | 1.38 [45] |

Birefringence | negative uniaxial | biaxial | isotropic |

Mass density [$\mathrm{g}/{\mathrm{c}\mathrm{m}}^{3}$], ρ | 3.98 | 3.69 [49] | 4.56 [48] |

Melting point [°C] | 2040 | 1870 | 1970 |

Specific heat capacity [J/g°C], Cp | 0.761 | 1.05 [46] | 0.59 [48] |

Knoop hardness [$\mathrm{k}\mathrm{g}/{\mathrm{m}\mathrm{m}}^{2}$] | 1800 (//c), 2200 (//a) | 1600–2300 [50] | 1320 [48] |

Thermal conductivity [W/K.m], $[\mathrm{W}/\mathrm{K}\cdot \mathrm{m}]\kappa $ | 30.3 (//a), 32.5(//c) [51] 1000 (@ 77 K) [52] | 28 [44] | 10 [53] |

Thermal expansion coefficient $[{\times 10}^{-6}/\mathrm{K}],\phantom{\rule{thickmathspace}{0ex}}\alpha $ | 4.8 and 5.3 [53], 0.34 (@ 77 K) [52] | 5.9 (//a), 6.1 (//b), 6.7(//c) [54] | 6.7 [53] |

Temperature dependence of refractive index [${\times 10}^{-6}\phantom{\rule{thickmathspace}{0ex}}/\mathrm{K}$], dn/dT | 13 [45], 1.9 (@ 77 K) [52] | 5.9 (//a), 6.9 (//b), 15.2 (//c) [54] | 9.9 [45] |

Young modulus [${\times 10}^{9}\phantom{\rule{thickmathspace}{0ex}}\mathrm{P}\mathrm{a}$], E | 335 | 469 [49] | 310 [48] |

Poisson’s ratio, $\nu $ | 0.29 | 0.3 | 0.3 [48] |

Fracture toughness [${\times 10}^{6}\mathrm{P}\mathrm{a}\phantom{\rule{thickmathspace}{0ex}}{\mathrm{m}}^{1/2}$], ${\mathrm{K}}_{1c}$ | 2.2 [53] | 2.6 [46] | 1.4 [53] |

Tensile (fracture) strength [${\times 10}^{6}\phantom{\rule{thickmathspace}{0ex}}\mathrm{P}\mathrm{a}$], ${\sigma}_{f}$ | 440 | 520 | 280 |

Thermal FOM [$\mathrm{W}/{\mathrm{m}}^{1/2}$], ${\mathrm{R}}_{T}^{\mathrm{n}}$ | 22 [53] | 14 [46] | 5.1 [53] |

Thermal shock resistance parameter [W/cm], ${\mathrm{R}}_{T}$ | 44 | 28 | 10.2 |

Maximum temperature difference before cracking [°C], $\mathrm{\Delta}{T}_{\mathrm{m}\mathrm{a}\mathrm{x},\mathrm{d}\mathrm{i}\mathrm{s}\mathrm{k}}$ | 740 | 460 (//a and //b), 400 (//c) | 380 |

Quantum defect (%), ${\mathrm{q}}_{d}$ | 35 | 11 (681 nm), 17 (640 nm) | 9 |

Emission cross section [${\times 10}^{-20}\phantom{\rule{thickmathspace}{0ex}}{\mathrm{c}\mathrm{m}}^{2}$], ${\sigma}_{\mathrm{e}\mathrm{m}}$ | 15 (//a), 41 (//c) [14] | $\sim 0.55\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}{25}^{\circ}\mathrm{C}$, $\sim 1.3\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}{100}^{\circ}\mathrm{C}$ (//b) | 2.1 [48] |

Fluorescence lifetime [µs], ${\tau}_{f}$ | 3.2 [55] | 262 [56] | 940 [45] |

Gain product [${\times 10}^{-26}\phantom{\rule{thickmathspace}{0ex}}{\mathrm{c}\mathrm{m}}^{2}\mathrm{s}$] ${\sigma}_{\mathrm{e}\mathrm{m}}{\tau}_{f}$ | 48 (//a), 131 (//c) | 130 @ 25°C (//b), 163 @ 100°C (//b) | 1975 |

${T}_{1/2}$ [°C] | $\sim 80$ [14,38] | 530 | – |

Intrinsic slope efficiency [%], ${\eta}^{\circ}$ | 64 [57] | 65 [41] | $>85$ [58] |

Relative strength of laser ESA, ${\mathrm{f}}_{l}={\sigma}_{l,\mathrm{e}\mathrm{s}\mathrm{a}/}{\sigma}_{\mathrm{e}\mathrm{m}}$ | $\sim 0$ [14] | $\sim 0.07\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}{25}^{\circ}\mathrm{C}$, $\sim 0.17\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}{100}^{\circ}\mathrm{C}$ [59] | $\sim 0$ [60] |

Relative strength of pump ESA, ${\mathrm{f}}_{p}={\sigma}_{p,\mathrm{e}\mathrm{s}\mathrm{a}/}{\sigma}_{\mathrm{a}\mathrm{b}\mathrm{s}}$ | $\sim 0$ | $\sim 0.7\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}640\phantom{\rule{thickmathspace}{0ex}}\mathrm{n}\mathrm{m}$, $\sim 0.01\phantom{\rule{thinmathspace}{0ex}}@\phantom{\rule{thinmathspace}{0ex}}681\phantom{\rule{thickmathspace}{0ex}}\mathrm{n}\mathrm{m}$ [61] | $\sim 0$ |

Passive losses [%/cm] | 2 [62] | 0.06 [41] | 0.3 |

Crystal FOM | 150 [62] | 3000 [43] | 3000 |

Nonlinear refractive index [${\times 10}^{-16}\phantom{\rule{thickmathspace}{0ex}}{\mathrm{c}\mathrm{m}}^{2}/\mathrm{W}$], ${\mathrm{n}}_{2}$ | 3.2 [27] | 2 [49], 3.54 [63] | 6.9 [64] |

Group velocity dispersion (${\mathrm{f}\mathrm{s}}^{2}/\mathrm{m}\mathrm{m}$), GVD | 56.6 [65] | 60.7 [66] | 66.6 [67] |

Third-order dispersion (${\mathrm{f}\mathrm{s}}^{3}/\mathrm{m}\mathrm{m}$), TOD | 41.4 [65] | 39.5 [66] | 66.7 [67] |

Gain bandwidth, FWHM (nm) | 260 | 55 | 8 |

Tuning range [nm] | 660–1180 [12] | 701–858 [15–19] | 1016–1108 |

Minimum theoretical pulse duration [fs] | 3.5 | 11.9 | 26 |

Demonstrated shortest pulse duration [fs] | $\sim 5$ [13] | 70 [31] | 35 [68] |

Polarizability difference [$\times {10}^{-26}\phantom{\rule{thinmathspace}{0ex}}\phantom{\rule{thinmathspace}{0ex}}{\mathrm{c}\mathrm{m}}^{3}$] | $\sim -100$ [69] | $\sim 25$ [70] | 1.95 [71] |