*** 9632301 Hsu This Phase I STTR project will research and develop novel fiber Fabry-Perot tunable filters (FFP-TFs) based on fluoride fibers (specifically ZBLAN fibers), and the application of FFP-TFs in the generation of high-power, narrow-linewidth, and wavelength-tunable Pr-doped ZBLAN fiber lasers in the 1.3 um wavelength region. Recent major advances in Praseodymium (Pr)-doped fluoride glass fibers have made them the most desirable medium for fiber amplifiers and lasers at 1.3~1m wavelength. The availability of prototype Pr-doped fiber amplifiers for 1.3 um wavelength-division-multiplexing (WDM) has heightened the need for 1.3~m lasers. Commercially available widely-tunable laser sources are typically based on grating-tuned external-cavity semiconductor lasers suitable only for laboratory environment. The requirement for 1.3 um tunable lasers that are fiber-compatible, robust, and cost-effective makes an all-fiber based tunable laser structure the best candidate. These lasers will allow telecommunication systems to access an additional 100nm of frequency spectrum using standard 1.3~m single-mode fibers which have been widely installed throughout the world. In addition, the resultant work will enable broad-based ZBLAN fiber device technology development that can be extended to other wavelength regions, e.g., to tunable upconverted blue-green lasers and mid-IR lasers using appropriate dopants in ZBLAN fibers. Additional applications using such new tunable lasers span from holographic data storage (tunable blue-green lasers) and free space optical communication to spectroscopy and environmental sensing (with tunable mid-IR lasers). ***