Photoluminescence of focused ion beam implanted Er$^{3+}$:Y$_{2}$SiO$_{5}$ crystals

Erbium doped low symmetry Y$_2$SiO$_5$ crystals attract a lot of attention in perspective of quantum information applications. However, only doping of the samples during growth is available up to now, which yields a quite homogeneous doping density. In the present work, we deposit Er$^{3+}$-ions by the focused ion beam technique at Yttrium sites with several fluences in one sample. With a photoluminescence study of these locally doped Er$^{3+}$:Y$_2$SiO$_5$ crystals, we are able to evaluate the efficiency of the implantation process and develop it for the highest efficiency possible. We observe the dependence of the ion activation after the post-implantation annealing on the fluence value.