All-Optical RZ Data Conversion With Temporally and Spectrally Gain-Sliced Semiconductor Optical Amplifier Via Broadband Optical Injection

We investigate the effect of the backward injecting linewidth on the rise/fall time, duty cycle, and frequency chirp of the 10 Gb/s format-converted pulsed return-to-zero (RZ) data stream from the traveling-wave semiconductor optical amplifier (TWSOA) with its gain profile temporally and spectrally reshaping by a backward injected single- or multimode inverse-optical-comb. The rising time remains almost unchanged; however, the falling time was monotonically reduced by increasing injection power. The evolution of full-width at half-maximum with injection power exhibits similar trend with falling time. In comparison with single-mode inverse-optical-comb injection, the multimode injection exhibits frequency-chirp reduction and better on/off extinction performances. Under the injection of multi- and single-mode inverse-optical-combs into the TWSOA at extremely high gain condition, the multi- and single-mode injection converted pulsed RZ data pulsewidths are 32 and 31 ps with corresponding peak-to-peak chirps of 10 and 12 GHz, respectively. The chirp can abruptly be reduced to 1.2 GHz by reducing the TWSOA biased current to 100 mA.