Fig. 1. Experimental arrangement for valence state manipulation in Sm3+-doped sodium aluminoborate glass using a femtosecond laser pulse shaping method. C₁ and C₂ stand for two cylindrical mirrors, M₁ and M₂ are two circular mirrors, G₁ and G₂ are two gratings, and L₁ and L₂ are two focusing lenses. Here, a continuous wave (CW) laser with a wavelength of 532 nm is used to detect the valence state change of Sm3+ ions. The inset shows a picture of the glass sample after the femtosecond laser irradiation.

Fig. 2. (a) Femtosecond laser spectrum using π phase step modulation (dark cyan dashed line) and (b) the shaped femtosecond laser pulse shapes with π phase step positions of 796 (orange line), 800 (pink line), and 804 nm (dark cyan line), together with the transform-limited (TL) laser pulse (gray line).

Fig. 3. (a) Luminescence spectra before (dark cyan line) and after (orange line) the shaped femtosecond laser irradiation and (b) the difference between the two luminescence spectra.

Fig. 4. (a) Absorption spectra of the glass sample before and after the femtosecond laser irradiation and (b) the difference between the two absorption spectra.

Fig. 5. Luminescence intensities at a wavelength of (a) 686 and (b) 600 nm with an increasing laser shot number for π phase step positions of 750 (black squares), 790 (red circles), 796 (cyan left-pointing triangles), 800 (green upward-pointing triangles), 804 (magenta right-pointing triangles), and 810 nm (blue downward-pointing triangles). Here, the experimental data in (a) and (b) are fitted by the exponential and sigmoidal functions, respectively.

Fig. 6. Luminescence intensities at a wavelength of 686 nm with an increasing laser shot number for π phase step positions of 750 (black squares) and 800 nm (red circles) under the same peak laser intensity of 1.3×1013  W/cm2.

Fig. 7. (a) Schematic of electron–hole generation in the glass sample by a (2+1) resonance-mediated three-photon absorption in Sm3+ ions, (b) the theoretical calculation of three-photon transition probability by π phase step modulation, together with the corresponding luminescence intensity modulation shown in Fig. 5(a) (circles).