New Mid-IR Laser Power Scaling Technology via Fiber Combiner

Beam combining devices are extensively used to achieve power levels that cannot be reached by the use of just a single laser. To achieve beam combination these devices commonly employ free-space optical components, like mirrors, gratings and lenses. The use of free-space optics has several issues such as sensitivity to thermal and vibration induced misalignment, complex packaging and bulky design. Fiber beam combining, while also allowing the achievement of high power levels, has the additional benefit of being compact and robust permitting simple packaging and meeting stringent environmental requirements like those encountered in mid-infrared countermeasure (IRCM) applications. Mid-wave infrared (MWIR) fiber combiners are currently not available but are needed for next generation IRCM laser systems. Chalcogenide fiber offers a good building block for such device offering low-loss transmission in the MWIR (2-5um) and excellent power handling. Considerable progress has been made in all-fiber beam combiners based on chalcogenide glass fibers, however further improvement to the fabrication technology and combiner design is needed to meet IRCM requirements. The proposed effort will demonstrate the feasibility of developing high-power low-loss fiber combiner based on chalcogenide glass fibers. This work will bring modifications and improvements to current device fabrication processes and design.