A discretely tunable mode-locked laser with 32 wavelengths and 100-GHz channel spacing using an arrayed waveguide grating

In this letter, we demonstrate a tunable mode-locked laser (time-to-wavelen gth mapped laser) with a 100-GHz channel spacing (1535.5-1560.5 nm) that us es a 32-wavelength silica-on-silicon planar light-wave circuit arrayed wave guide grating (AWG) for realizing a wavelength-dependent delay. The wavelen gth is selected by changing the mode-locking frequency. Mode-locking was re alized by modulating the electroabsorption modulator (similar to 10 GHz) or the gain of the semiconductor amplifier (similar to5 GHz). By matching the period of the Fabry-Perot resonances in the InGaAsP device with the channe l spacing of the AWG, wavelength tuning was realized over a broad wavelengt h range by only changing the mode-locking frequency.