1：Experimental Design and Method Selection:

Optical spectroscopy was used to study the light-induced effects in BiFeO3 single crystals. The absorbance spectra were calculated from transmission spectra before and during laser illumination.

2：Sample Selection and Data Sources:

A high phase-purity BiFeO3 single crystal grown by the flux method was used. The sample was mounted on a cold-finger Mikro-cryostat for temperature-dependent measurements.

3：List of Experimental Equipment and Materials:

A Bruker Hyperion infrared microscope coupled to a Bruker Vertex 80v FTIR spectrometer with a Si diode detector was used. A blue laser (MBL-III-473 from CNI) was used for illumination.

4：Experimental Procedures and Operational Workflow:

Transmission measurements were performed in the frequency range from 8500 cm?1 to 20,000 cm?1 (1.05 eV–2.48 eV) at temperatures from 295 K to 20 K. The laser beam was deflected onto the sample via a 45° aluminum mirror.

5：05 eV–48 eV) at temperatures from 295 K to 20 K. The laser beam was deflected onto the sample via a 45° aluminum mirror. Data Analysis Methods:

5. Data Analysis Methods: Absorbance spectra were calculated from transmission spectra. The transmission difference was calculated to identify light-induced absorption features. Breit-Wigner-Fano (BWF) lineshape fitting was used to determine the energy positions and intensities of the absorption features.