Wide and fast wavelength-tunable mode-locked fiber laser based on dispersion tuning.

We demonstrate a wide and fast wavelength-tunable modelocked fiber laser based on tuning the mode-locking frequency. The laser is in a sigma-laser configuration, and a wideband semiconductor optical amplifier (SOA) at 1.3 mum wavelength region is used as a gain medium. Mode locking is achieved by direct modulation of the injection current to the SOA, and a dispersion compensation fiber (DCF) is used to provide desired intracavity dispersion. By tuning the modulation frequency, a wide tuning range over 100 nm is achieved. Lasing wavelength is measured to be linearly in proportion to the RF frequency applied to the SOA. The sweep rate over the entire wavelength range (100 nm) can be raised to be as high as 200 kHz.