Controlled compositional disorder in Er3+:Y2SiO5 provides a wide-bandwidth spectral hole burning material at 1.5 μm

The subgigahertz spectral bandwidth of the lowest energy 1.5 mu m Er3+ I-4(15/2)-> I-4(13/2) optical transition in Er3+:Y2SiO5 has been increased to similar to 22 GHz by intentionally introducing compositional disorder through codoping with Eu3+ 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 Er3+ 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 Er3+ 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 mu m based on spectral hole burning.