Abstract

A high-power optical frequency comb at $2.06\mathrm{\mu m}$ has been generated using a Ho:YLF multipass amplifier seeded by the long wavelength supercontinuum tail of an octave-spanning Er:fiber comb source. The Ho:YLF amplifier showed a net gain larger than $30\mathrm{dB}$ from 2048 to $2068\mathrm{nm}$, allowing the generation of a $20\mathrm{nm}$ bandwidth comb with a mode spacing of $100\mathrm{MHz}$ and a power per mode ranging from 20 to $370\mathrm{\mu W}$. In the time domain, the amplified comb corresponds to a pulse train with $1.6\mathrm{W}$ total power and $508\mathrm{fs}$ transform-limited pulse duration. Using a self-referencing $f-2f$ interferometer and a phase-locking loop, spectral narrowing of the offset frequency down to less than $17\mathrm{Hz}$ has been achieved.

© 2011 Optical Society of America