Gradient index optical element

A gradient index optical element, comprising:

• at least one first metal dopant g selected from the group consisting of As, La, In and Y and at least one second metal dopant f selected from the group consisting of Bi, Sb, Nb, Ti, Ta, Pb and Tl, in which the first metal dopant g and the second metal dopant f are distributed in the same direction in a medium and a content of the second metal dopant f is not less than 20 mol % in a greatest portion of the second metal dopant distribution.

A gradient index optical element, comprising:

• at least one first metal dopant selected from the group consisting of La, Y, Ga, In, Ge, Sn, Zn, Zr, Ba, Ca, As, Sr, Gd and Be, the first metal dopant being distributed at a concentration gradient in a medium, the concentration gradient of the first metal dopant defining a slope having a direction;
• and at least one second metal dopant different from the first metal dopant and selected from the group consisting of Bi, Sb, Nb, Ti, Ta, Pb, Tl, Zr, In, Sn, Y, Ba, Ca and Sr, the second metal dopant being distributed at a concentration gradient in the medium, the concentration gradient of the second metal dopant defining a slope smaller than the slope of the concentration gradient of the first metal dopant, and the slope of the concentration gradient of the second metal dopant being in the same direction as the slope of the concentration gradient of the first metal dopant.

A gradient index optical element, comprising:

• at least one first metal dopant selected from the group consisting of As, La, In and Y, the first metal dopant being distributed in a medium and having a concentration gradient defining a slope having a direction;
• and a second metal dopant selected from a group consisting of Bi, Sb, Nb, Ti, Ta, Pb and Tl, the second metal dopant being distributed in the medium and having a concentration gradient defining a slope having the same direction as the slope of the concentration gradient of the first metal dopant, and a content of the second metal dopant being at least 20 mol % at a greatest portion of the second metal dopant distribution.