Controlled compositional disorder in Er 3 + : Y 2 Si O 5 provides a wide-bandwidth spectral hole burning material at 1.5 μ m

Abstract

The subgigahertz spectral bandwidth of the lowest energy $1.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ ${\mathrm{Er}}^{3+}$ $^{4}I_{15∕2}\ensuremath{\rightarrow}^{4}I_{13∕2}$ optical transition in ${\mathrm{Er}}^{3+}:{\mathrm{Y}}_{2}\mathrm{Si}{\mathrm{O}}_{5}$ has been increased to $\ensuremath{\sim}22\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ by intentionally introducing compositional disorder through codoping with ${\mathrm{Eu}}^{3+}$ impurity ions. This illustrates a general bandwidth control technique for spectral hole burning device applications including spatial-spectral holography and quantum computing. Coherence measurements by stimulated photon echoes demonstrated that the increased disorder does not perturb the dynamical properties of the ${\mathrm{Er}}^{3+}$ transition and, thus, gives the desired bandwidth enhancement without penalty in other properties. The echo measurements and model analysis also show that phonon-driven spin flips of ${\mathrm{Er}}^{3+}$ ions in the ground state are responsible for the spectral diffusion that was observed for the optical transition. These results collectively give a better understanding of both the nature of disorder and of the ion-ion interactions in doped materials, and they also enable the high bandwidths required for signal processing and memory applications at $1.5\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ based on spectral hole burning.