  We report a mode-locked Ti:sapphire femtosecond laser with 5GHz repetition
rate. Spectral broadening of the 24 fs pulses in a microstructured fiber yields
an octave-spanning spectrum and permits self-referencing and active
stabilization of the emitted femtosecond laser frequency comb (FLFC). The
individual modes of the 5GHz FLFC are resolved with a high-resolution
spectrometer based on a virtually imaged phased array (VIPA) spectral
disperser. Isolation of single comb elements at a microwatt average power level
is demonstrated. The combination of the high-power, frequency-stabilized 5GHz
laser and the straightforward resolution of its many modes will benefit
applications in direct frequency comb spectroscopy. Additionally, such a
stabilized FLFC should serve as a useful tool for direct mode-by-mode Fourier
synthesis of arbitrary optical waveforms.
