Final Report : Novel Optical Fiber Materials With Engineered Brillouin Gain Coefficients SSL - 1 : NOVEL FIBER

Final Report: Novel Optical Fiber Materials With Engineered Brillouin Gain Coefficients SSL-1: NOVEL FIBER LASERS Report Title This 2-year program (with 1 year no-cost extension) sought to investigate novel optical materials suitable for use in high-power narrowlinewidth fiber lasers. A complete model for the mass density, acoustic velocity, acoustic attenuation, photoelastic (Pockels’) coefficients, and refractive index has been developed for multi-component glasses. It has been utilized to characterize several materials (data are provided herein), including Group I and II oxides, MgAl2O4 (spinel), alumina, LuAG (a garnet), and several rare earths (RE2O3), including determination of compositions that give rise to near-zero Brillouin gain. Fibers were produced from these precursors (crystal and glass phase), clad in silica, utilizing the molten core processing technique. Measurement test beds have been developed to determine the key acoustic and photoelastic constants of these fibers, in order to validate the model. Within the scope of this work, suppression of Brillouin scattering by >10dB relative to conventional fiber has been ‘routine.’ Furthermore, we have investigated some rare-earth-doped versions of these fibers, and other novel materials have been identified as promising and these were continued to be studied during the extension period. We point out that this limited report represents only highlights from the numerous findings accumulated during this program. They can be found in greater detail in the roughly 175 printed pages in the resulting 17 journal publications (quite a bit more if one includes a number of archival conference proceedings). (a) Papers published in peer-reviewed journals (N/A for none) Enter List of papers submitted or published that acknowledge ARO support from the start of the project to the date of this printing. List the papers, including journal references, in the following categories: