Physics-based large-signal modeling and load-pull optimization for MUTC-PDs

To enhance the output power, the load-pull technique is applied to MUTC-PDs to mitigate the voltage swing effect. To characterize the self-induced field, a physics-based nonlinear large-signal equivalent circuit model is proposed. An automated electromagnetic-circuit co-optimization framework is then established using Bayesian optimization and the harmonic balance method. Theoretical load-pull analysis indicates that the output power at 30 GHz is enhanced from 16.7 dBm to 21.4 dBm. By co-optimizing CPW electrodes or flip-chip substrates as matching networks for the 50 Ω load, simulated output power levels of 18.8 dBm and 19.3 dBm are achieved, respectively. This demonstrates that load-pull techniques offer a promising approach for future high-speed photonic systems.