High SBS-Threshold Er/Yb Co-Doped Phosphate Glass Fiber Amplifiers for High Power, Sub-us Pulsed, Narrow Linewidth, All Fiber-Based Laser Transmitter

In Phase I, NP Photonics has achieved 1.2 kW peak power for 105 ns fiber laser pulses, and successfully demonstrated the feasibility to produce monolithic high SBS threshold narrow linewidth fiber amplifiers for all fiber-based laser transmitters ideally suited to NASA's active remote sensing spectroscopy. In Phase II, NP Photonics proposes to develop prototypes or products of the high SBS-threshold, Single-Mode (SM), polarization maintaining (PM), high power amplifiers operating with sub-microsecond pulses and transform-limited linewidth. This is based on the successful demonstrations in Phase I by using NP's proprietary patented large core SM PM highly Er/Yb co-doped phosphate glass fibers. Furthermore, in order to push the SBS threshold to the 100s kW level and to demonstrate even higher SBS threshold and improved conversion efficiency for 100-500 ns transform-limited fiber laser pulses, a new large core SM PM photonic crystal phosphate fiber 100/400 will be designed and fabricated in Phase II. It will be used to build the 3rd power amplifier stage in order to offer prototype/product services by achieving 10s kW peak power and 5-mJ pulse energy free of SBS effects. This will more fully enable NASA's active remote sensing with fiber laser pulses at 765 nm by using NP's Single Mode phosphate fiber amplifiers.