We found that ${\mathrm{Ce}}^{3+}:{\mathrm{Lu}}_2{\mathrm{Si}}_2{\mathrm{O}}_7$ single crystals could be excited at $800\mathrm{nm}$ by using a femtosecond Ti:sapphire laser. The emission spectra of ${\mathrm{Ce}}^{3+}:{\mathrm{Lu}}_2{\mathrm{Si}}_2{\mathrm{O}}_7$ crystals were the same for one-photon excitation at $267\mathrm{nm}$ as for excitation at $800\mathrm{nm}$ . The emission intensity of ${\mathrm{Ce}}^{3+}:{\mathrm{Lu}}_2{\mathrm{Si}}_2{\mathrm{O}}_7$ crystals was found to depend on the cube of the laser power at $800\mathrm{nm}$ , consistent with simultaneous absorption of three $800\mathrm{nm}$ photons. The measured value of the three-photon absorption cross section is $\sigma ^{\prime }{}_3=2.44\times {10}^{-77}{\mathrm{cm}}^6{\mathrm{s}}^2$ .