High-energy femtosecond fiber laser at 1.6 microns for corneal surgery

We present a compact femtosecond fiber laser at 1.6 mu m based on chirped-pulse amplification in an erbiumdoped large-mode-area fiber. In erbium-doped fibers, low gain at 1.6 mu m increases the fiber length needed to achieve amplification, which enhances nonlinear phase accumulation. In this work, 12 m of a 20-mu m-diameter core highly-doped fiber was used to reduce nonlinearities. Nonlinear compensation of the stretcher/compressor dispersion mismatch results in the generation of 605 fs pulses at 300 kHz with an energy of 1.5 mu J. This is, to our knowledge, the first sub-picosecond laser reaching the mu J level at 1.6 mu m in erbium-doped fibers.