1. Spectral Diffusion (in Rare-Earth-Doped Materials) Aislinn Daniels Spectrum Lab Seminar Fall 2015 Spectrum Lab Montana State University

2. Summary What is Spectral Diffusion? What causes Spectral Diffusion? Effects on Measurements ◦Example Measuring Spectral Diffusion Reducing Spectral Diffusion Spectrum Lab Montana State University

3. What is Spectral Diffusion? Changes in an atom’s or ion’s transition frequency as a function of time Accumulated frequency shifts cause the ions to “random walk” in frequency space Causes spectral “broadening” of material Spectrum Lab Montana State University

4. What is Spectral Diffusion? Spectrum Lab Montana State University

5. What is Spectral Diffusion? Spectrum Lab Montana State University

6. What Causes Spectral Diffusion? Spectrum Lab Montana State University

7. Effects on Measurements from Magnetic Dipole Interactions Spectrum Lab Montana State University

8. Effects on Measurements from Magnetic Dipole Interactions, Example Spectrum Lab Montana State University

9. Effects on Measurements from Magnetic Dipole Interactions, Example Spectrum Lab Montana State University

10. Measuring Spectral Diffusion Use theoretical descriptions of spectral diffusion for the specific setup (as in example) to fit echo intensity data to find  eff Then, variations in other parameters (concentration of rare-earth ions, temperature, external magnetic field, etc.) can be used to find parameters  SD and R from  eff Why measure it? ◦Corrections for other measurements ◦Characterizes material Spectrum Lab Montana State University

11. Reducing Spectral Diffusion For rare-earth-doped materials with paramagnetic ions, ◦Lower temperature of system ◦Increase magnetic field (prevents dipole flips) ◦Reduce concentration of ions in crystal ◦For three-pulse echo systems, decrease T w and/or t 12 Similar approaches for other systems and pulse configurations Spectrum Lab Montana State University

12. References Böttger, Thomas, C. W. Thiel, Y. Sun, and R. L. Cone. "Optical Decoherence and Spectral Diffusion at 1.5 μ M in Er 3 : Y 2 SiO 5 versus Magnetic Field, Temperature, and Er 3 Concentration." Phys. Rev. B APS Physics 73.7 (2006): n. pag. Physical Review B. Web. 1 Dec. 2015. Special thanks to Randy Babbitt for answering my questions. Spectrum Lab Montana State University