Scientists at Technische Universität München in Garching and at Ludwig Maximilians Universität München in Munich, both in Germany, have presented an erbium-doped fiber laser system that offers 110 mW of linearly polarized output power in 65-fs pulses at a repetition rate of 67 MHz. They suggest that the system, which they reported in the March 24 issue of Optics Express, is suitable for the production of optical combs between 540 and 1900 nm for use in optical frequency metrology applications such as optical clocks.To date, researchers in this field largely have employed relatively expensive Ti:sapphire lasers. The new system comprises a diode-pumped Er:fiber oscillator, a fiber pulse stretcher and a 2-m Er:fiber amplifier, and a silicon prism assembly to recompress the emerging pulses. Injecting the pulses into a 7-cm length of polarization-maintaining highly nonlinear dispersion-shifted fiber yielded an octave-spanning supercontinuum that maintained the comb structure from the amplifier.