Abstract

We report a high-energy femtosecond fiber amplifier based on an air-cladded erbium-ytterbium-codoped photonic-crystal fiber with a 26-µm mode-field diameter. 700-fs, 47-MHz pulses at 1557 nm are amplified and compressed to near-transform-limited 100-fs, 7.4-nJ pulses with a 350-mW average power. Owing to the reduced nonlinearity, even without chirped-pulse amplification we obtained as high as a 54-kW peak power, which exactly coincides with the peak power of a 100-fs fundamental soliton. Perfect single-transverse-mode (with M²<1.05) and single-polarization (polarization extinction ratio=42 dB) properties are preferable for many applications.

© 2005 Optical Society of America