1：Experimental Design and Method Selection:

The nonlinear optical properties of Yb:YAG ceramics were characterized by the Z-scan method at 800 nm.

2：Sample Selection and Data Sources:

Yb:YAG transparent ceramics with doping concentrations of 1 at%, 2 at%, 5 at%, 10 at%, 15 at% and 20 at% were prepared by the solid-state reactive sintering method.

3：List of Experimental Equipment and Materials:

A femtosecond laser with a wavelength of 800 nm, pulse duration of 100 fs and repetition rate of 1 kHz was used. The laser intensity was tuned by an optical attenuator. The beam waist radius was ~80 μm at the focal point.

4：Experimental Procedures and Operational Workflow:

The ceramic sample was placed on a motorized translation stage illuminated by the femtosecond laser. The open-aperture and closed-aperture signals were obtained by detecting the transmitted beam completely and partially, respectively.

5：Data Analysis Methods:

The normalized transmittance was fitted by specific equations to extract the nonlinear absorption coefficient and nonlinear refractive index.