Time Domain and Nyquist Analysis of InGaAs-GaAs Semiconductor Self-Assembled Quantum Dot Lasers Based on Transfer Matrix Method

AAbstract: Transfer function of the InGaAs/GaAs SAQD laser is calculated using its rate equations. Using the calculated transfer function, time and frequency analysis can be implemented completely. In the time domain, the calculated transfer function can show the transient and steady state response of the laser. Also this transfer function can be used in circuit simulator such as SPICE in order for analyzing the electro-optical VLSI circuits. After the calculation of the transfer function, time domain together with Nyquist responses has been calculated. The effect of carrier dynamics on the output response of the laser is analyzed in this case. Nyquist diagram is selected in this analysis because one can predict the closed loop system using the open loop system. Unlike the systems such as interconnects and transistors that are analyzed before, the results reveal that in SAQDLs, the ratio of the transient peak overshoot in the output power to stable output power is very large. Accordingly in integrated circuits that use SAQDLs, amplification of each overshoots in output power of the laser can deteriorate the input of the next circuit module on the chip or shock to it. This increases the importance of the stability analysis in SAQDLs for more reliability.