10-GHz Ultrashort Optical pulse and Ultraflat Optical Comb Generation via a Semiconductor Mode-locked Laser

We report a 10-GHz ultrashort pulse and optical comb generation using a quantum well (QW) semiconductor mode-locked laser (SMLL). With a dilute waveguide design, ultrashort pulses with pulse widths as short as 726 fs were also obtained from a 10-GHz SMLL without any compression, and the shortest pulse width of 576 fs was achieved after pulse compression. Direct generation of a flat comb with a −3-dB bandwidth of 9.92 nm (>125 comb lines in a span of 1.24 THz) and a −20-dB bandwidth of 19.22 nm (>240 comb lines in a span of 2.4 THz) was obtained. A further comb span extension was obtained by pumping a highly nonlinear fiber (HNLF) via the SMLL. A −20-dB bandwidth of 89.4 nm and a usable comb span of over 110 nm were demonstrated.