Theoretical analysis of relative intensity noise in semiconductor QD lasers

In this study, the relative intensity noise (RIN) and modulation response of a 1.3 μm InAs/InGaAs quantum dot (QD) laser are investigated using a rate equation model in the presence of Langevin noise sources and small-signal analysis. Results demonstrate that carrier noise in the ground state and excited states increases the amplitude of the RIN, and the RIN in QD lasers declines with an increase in injection current. Due to the decreased ambient temperature, the output power and modulation bandwidth increase, and the RIN decreases. According to the results, the maximum achievable modulation bandwidth and output power and the minimum RIN value could not be achieved at the same bias current. An optimal performance factor (OPF) can be introduced to achieve the best possible QD laser performance in terms of RIN, maximum modulation bandwidth, output power, and electrical current consumption. Despite the fact that the minimum available RIN is −150 dB/Hz and the maximum modulation bandwidth is 7.95 GHz at two different bias currents, the OPF results at the optimum point reveal a modulation bandwidth of 7.64 GHz and a minimum RIN of −140 dB/Hz with 26 mW output power at 36-mA bias current.