Tunable luminescence of CaO-Al_2O_3-GeO_2 glasses

We report tunable luminescence in oxygen-deficient CaO-Al(2)O(3)- GeO(2) glasses. The glass samples were prepared by adding metal Al instead of corresponding oxide (Al2O3). Efficient blue and red emissions were observed when excited by 300 and 370 nm ultraviolet light, respectively. By adjusting the content of metal Al, we could control the quantities of the defects which results in tunable luminescence from blue to white to red. Furthermore the resultant oxygen-deficient glasses have shown bright white luminescence when the excitation wavelength tuned to 335nm. Our method opens a new route for the white light illumination.