This small business innovation research is aimed to generate tens of mJ pulse energy in a pulse width of < 10 n-sec from an air-cooled multicore fiber laser array. This laser can be packaged into a compact and light-weight enclosure that requires a minimum thermal management. PC Photonics has demonstrated coherent power-combining of a 7-core and also a 19-core Yb-doped fiber laser array embedded in a common cladding. The Company has also obtained Q-switched pulses from the 7-core fiber laser with an output pulse energy of ~ 1 mJ with < 20 n-sec pulse width. A kinetic model has been established to verify our experimental results and to predict the performance of Q-switched multicore fiber lasers. This proposal presents a detailed description of a 37-core Yb-doped fiber laser, which is capable of generating > 12 mJ pulse energy in a width of < 10 n-sec at Q-switching rates ranging from 0.4 to 10 kHz. Because fiber laser has very high optical conversion efficiency and does not require cooling, it is suitable for space-borne system applications. Under Phase I a conceptual design analysis for a high-energy pulsed fiber laser utilizing multicore fiber laser technology will be performed with the emphasis on the fiber architecture and fast Q-switching techniques to achieve highest pulse energy in very short duration. Another key issue to be addressed in Phase I is the power damage at the active region due to very high peak intensity (~ 4 GW/cm2). To alleviate this problem, the silica fiber material quality must be greatly improved, because 4 GW/cm2 is far below the intrinsic material damage threshold of pure silica
