Materials for Optical Routers, Signal Processors, and Memories Based on Persistent Spectral Hole Burning

Abstract

Abstract : Optical signal processing devices using spectral hole burning were demonstrated, including an optical header decoder for packet switching and tests of signal correlator fidelity and phase-shift-keyed codes. New hole burning materials were developed and characterized. Performance improvements of the materials include: (a) multi-GHz bandwidths for signal processors, (b) increased capacity and storage time for data storage, (c) improved frequency stability for lasers stabilized to spectral hole frequency references. The new materials include Er(3+) compounds for 1.5 micron communications bands, Tm(3+), Pr(3+), Eu(3+), and Tb(3+) compounds, mostly in oxide crystal hosts. Tb(3+) compounds were characterized for photon gated persistent spectral hole burning. Electron photoemission spectroscopy was used to determine important relationships between ion levels and host bands and to develop gated persistent hole burning materials; those results have substantial corollary impacts on robustness and efficiency of solid-state laser materials, phosphors for displays, and scintillators for imaging. For all crystal materials - of any symmetry -angular orientation and polarization has been optimized for signal fidelity and fastest transient response in hole burning devices. There were 7 published journal articles, 16 invited presentations, 36 contributed presentations, and participation on 7 conference committees. The project involved five graduate students, nine undergraduates, three postdocs and scientists, along with the Pis. Other AFOSR-supported groups use these materials; Scientific Materials Corp. sells the materials.