Abstract

The output power of cw Yb-doped fibers (YDF) dramatically increases to achieve diffraction-limited beam using PCF (photonic crystal fiber) and LMA(large mode area) fiber. Recently, high power operation, such as a few kilowatts, are focused on the Yb-doped fiber operating around 1 µm region because an extremely high output efficiency of 60-80 % can be achieved. An excellent beam quality is also the benefit of fiber lasers because the thermal effect in fiber laser is smaller than that of bulk lasers. We have developed a high-peak and high-average power Yb-doped fiber laser system with second air-hole cladding structure. The near-field pattern of the output beam is near single mode (LP₀₁) due to a bend in part of multi-mode fiber.

© 2009 IEEE