Novel Method of Stimulated Brillouin Scattering (SBS) and Other Nonlinear Suppression for HEL High Power Fiber Delivery System

High-Energy Laser (HEL) systems on naval platforms can serve a vital role in naval defensive and offensive operations and ensure naval battle space supremacy and water space management. The Pentagon has identified directed energy weapons as an important priority because military officials believe employing lasers will dramatically decrease the cost and improve the effectiveness compared to conventional projectiles. Narrow-linewidth Yb-doped fiber lasers have attracted considerable interest over the past decade in high power beam spectral beam combining and coherent beam combining systems. Beam combining approaches are complicated by the high power and potential long transmission distances that result in unwanted non-linear effects. The two main non-linear effects are Stimulated Brillouin Scattering (SBS) and Stimulated Raman Scattering (SRS). SBS has smaller threshold and must be addressed to achieve successful beam combining. There are no commercial fibers available to provide high power transmission of narrow spectral width light of kW level single mode fiber lasers for distances of tens of meters and new fibers must be developed to enable high power beam combining. The Phase I program will demonstrate the feasibility of developing novel SBS suppressed fibers for beam combining applications.