10 GHz pulses generated across a ~100 nm tuning range using a gain-shifted mode-locked SOA ring laser.

Widely-tunable picosecond pulses have been generated from a harmonically mode-locked semiconductor optical amplifier (SOA) ring laser with a center wavelength spanning from 1491 to 1588 nm. An intra-cavity birefringence loop mirror filter is used to define a 1.6 nm comb that governs the wavelength spacing of the tunable output pulses. The filter also serves to control the spectral gain profile of the laser cavity and thus extends the tuning range. By exploiting the spectral shift of the SOA gain with different amount of optical feedback, the output can be obtained over a wid wavelength range. Applying mode-locking together with the dispersion tuning approach, 10 GHz picosecond pulses have been successfully generated over a tuning range of 97 nm.