8-fs pulses from a compact Er:fiber laser system

We introduce a versatile laser source of ultrabroadband pulses entirely based on polarization maintaining, telecom-compatible fibers. A self-starting oscillator generates seed pulses for three parallel Er:fiber amplifiers which remain synchronized with attosecond precision. Each branch delivers a train of 120-fs pulses with energy of 8 nJ at a repetition rate of 40 MHz. The key element for pulse compression is a two-stage assembly of a precompression fiber spliced to a highly nonlinear dispersion shifted bulk germanosilicate fiber for supercontinuum generation. Dispersion spectra measured in a white-light interferometer and FROG traces of the pump pulses serve as input parameters. This procedure allows us to design devices which generate ultrabroadband spectra or pulses with widely tunable center wavelength.