Repetition-rate-selective, wavelength-tunable mode-locked laser at up to 640 GHz.

We demonstrate a tunable passively mode-locked fiber laser with a selectable repetition rate of up to 640 GHz. The mode-locking mechanism is based on dissipative four-wave mixing in combination with a programmable optical processor as the spectral filter. We achieve up to 20 nm wavelength tunability and present mode-locked operation at repetition rates between 40 and 640 GHz. Measurements of the power spectra using a cross-phase modulation technique confirm the mode locking.