Continuously tunable multigigahertz repetition rate DFB laser pulsations

The generation of short optical pulses with a repetition rate up to 45 GHz has been realized by using a new method based on CW-light injection from one DFB into another CW operated DFB-laser with a proper frequency detuning. Extremely high extinction ratios of the pulsations could be controlled by two parameters: detuning and injection ratio. An optimized construction of the DBF-laser with respect to single-mode output power has been utilized. Two laser structures with ternary compressively strained In70Ga30As/In53Al23Ga24As/InP and quaternary strain compensated In71Al9Ga20As/In34Al21Ga45As/InP multiquantum wells (MQW), respectively, provided very high speed in combination with high (>20 mW) output power, low threshold current (<8 mA) and low temperature sensitivity (T-0 = 90K). Comparison of characteristics showed the advantages of lasers with attain compensated MQWs.