Characteristic optimization of 1.3-μm InGaAsP MQW lasers for direct modulation applications

Abstract

We have investigated 1.3-μm InGaAsP strained multi-quantum-well (MQW) lasers on InP substrate for direct modulation applications using the commercial laser simulator PIC3D. The physical mechanisms affecting the laser dynamic characteristics such as nonradiative recombination losses and vertical electron leakage effect are considered in our simulation. The number of wells is optimized because increasing the number of QWs can decrease the nonradiative recombination losses and increase the modal differential gain, nevertheless, the carrier distribution between wells become more non-uniform with too many QWs numbers resulting in uneven simulated recombination rate and increasing Auger recombination. The influence of barrier height is analyzed and a tradeoff has to be determined because too high barriers results in more nonuniform carrier distribution in the active regions, increasing the Auger recombination rate severely while the vertical current leakage outside the QWs will increase dramatically at lower barrier height. The 1.3-μm FP laser with the MQWs of 6 wells, 1.15 Q barriers bandgap and 8 wells, 1.1 Q barrier bandgaps is fabricated and characterized. The FP laser with MQWs structures composed of 8 compressive strain quantum wells and 9 barriers with the optimized bandgap 1.1 Q shows better properties. The threshold current is around 19 mA and the resonance frequency of 9.5 GHz and 3-dB bandwidth in excess of 13.3 GHz at 120 mA injection current. This modulation frequency is suitable for 10 Gbits/s optical data transmission.