Incorporation of Na in the dodecahedral site of the garnet structure contributes to the broadening of the Yb optical bandwidth. A reduction of the mode-locked  laser pulse duration can be expected.

Tetragonal double tungstates and double molybdates with NaLn(XO4)2 formula codoped wth Yb and Er have record values of thermal sensitivity based in the upconversion monitoring technique.  See publications

doi.org/10.1088/1361-6528/aa6834

doi.org/10.1371/journal.pone.0177596