TABLE OF CONTENTS In this section, the integrated TLLM model (parasitics and matching network included) was used to study a microwave signal generation technique known as harmonic generation by gain-switching. The simulation results obtained from the integrated TLLM model were then compared with the results from a lumped-element integrated laser model by Sum and Gomes [ [64]]. In contrast to the noiseless lumped-circuit models, the stochastic integrated TLLM model may be useful for investigating the effects of up-conversion of low-frequency noise in gain-switching [ [83], [84]].
The 6th subharmonic frequency (1.1 GHz) with +1 dBm power was injected into the integrated laser transmitter model to generate gain-switched optical pulses, which subsequently produced a comb of RF frequencies at harmonics of 1.1 GHz owing to laser nonlinearity. The RF power at these harmonic frequencies for both the matched and unmatched cases are compared in Fig. 15.27. When matched, the RF power increased for all harmonic frequencies and an improvement of 2 dB was achieved for the 6.6 GHz component. It can also be observed in Fig. 15.27 that the higher harmonics had greater improvement than the lower harmonics.
An analytical approach to investigate the effect of parasitics on the injected electrical pulse has been presented by Liu et al. [ [85]]. The presence of electrical parasitics tends to widen the input electrical pulse and reduces its peak amplitude. In the approach in [
