The subgigahertz spectral bandwidth of the lowest energy 1.5mum Er3+ I15/24-->I13/24 optical transition in Er3+:Y2SiO5 has been increased to ˜22GHz 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 1.5mum based on spectral hole burning.
Böttger, Thomas; Thiel, C. W.; Cone, R. L.; Sun, Y. Controlled compositional disorder in Er3+:Y2SiO5 provides a wide-bandwidth spectral hole burning material at 1.5mum. Phys. Rev. B 77, 155125 – Published 24 April 2008