Recent progress in developing new rare earth materials for hole burning and coherent transient applications

To develop new spectral hole burning materials and optimize known materials for applications such as optical correlator and memory devices, a broad range of experiments, from optical coherent transients to photoelectron spectroscopy, have been used to elucidate fundamental aspects of the rare-earth electronic structure. We report progress in the characterization of Er3+ doped materials where we have measured an ultra-narrow line width of 50 Hz in Er3+:Y2SiO5 and a Γinh/Γh ratio as high as 108 in Er3+:LiNbO3. Progress is also reported for Nd3+:YVO4 where the high oscillator strength is an advantage over other rare earth ions and excellent coherence properties can be achieved at modest magnetic fields. Finally, we report the advances in the pursuit of photon-gated hole burning materials through the study of the energies of the localized rare earth energy states relative to the host band states, providing the foundation for understanding photoionization in these materials.