Space-selective valence state manipulation of transition metal ions inside glasses by a femtosecond laser

We report the observation of space-selective oxidation of ${\mathrm{Mn}}^{\text{2+}}$ to ${\mathrm{Mn}}^{\text{3+}}$ in a transparent and colorless Mn and Fe ions codoped silicate glass at room temperature by using an 800-nm-femtosecond laser. Difference absorption spectrum of the glass after and before the irradiation of the focused infrared femtosecond pulsed laser showed that a portion of ${\mathrm{Mn}}^{\text{2+}}$ ions near the focused part of the laser beam inside the glass were oxidized to ${\mathrm{Mn}}^{\text{3+}}$ ions after the laser irradiation. ${\mathrm{Mn}}^{\text{3+}}$ ions were stable at the temperatures below 300 °C. It is suggested that ${\mathrm{Mn}}^{\text{2+}}$ ions act as hole trapping centers while ${\mathrm{Fe}}^{\text{3+}}$ ions as well as active sites in the glass matrix act as electron trapping centers. A promising application was demonstrated for the fabrication of three-dimensional colored image inside a transparent material.