Large Effective Mode Area Optical Fibers for High Power Lasers

Leakage channel fibers have demonstrated their ability to significantly extend the effective mode area of a fundamental mode while maintaining robust single mode operation. These fibers are designed to have strong built-in mode filtering which effectively suppresses the propagation of all higher order modes while keeping fundamental mode loss to a minimum, and, therefore, effectively extending the regime of single mode operation. Recently all-glass leakage channel fibers have been demonstrated as a significant improvement over designs with air holes. These all glass leakage channel fibers not only can be manufactured with much improved consistence and uniformity. They can also be handled and used as conventional fibers. More importantly, mode distortions from collapse of air holes in photonic crystal fibers during splicing and other end face treatments are largely eliminated. We will review some of the recent progress in this area.