Optimized pulse source for 40-Gb/s systems based on a gain-switched laser diode in conjunction with a nonlinearly chirped grating

The authors demonstrate the generation of short optical pulses, which display spectral sidemode suppression ratio, and temporal pedestal suppression ratio, well in excess of 30 dB. The exceptional spectral and temporal characteristics exhibited by these pulses are attained by employing a novel technology, based on an externally injected gain-switched laser in conjunction with a nonlinearly chirped grating. Using this technique, near transform limited 7-ps optical pulses, exhibiting a time bandwidth product of 0.49, are generated.