Field-Controlled Modulation Transport in Electro-Optically Accessible Semiconductor Microcavities for Ultrabroadband Optical Interconnects

Abstract Semiconductor microcavity light sources are fundamentally constrained in modulation speed by carrier–photon dynamics, which impose a relaxation-oscillation bottleneck on bandwidth scaling. Here we introduce an electro-optically integrated vertical-cavity surface-emitting laser platform and a field-controlled modulation transport framework in which cavity accessibility acts as an active transport variable. By integrating thin-film lithium niobate within a GaAs quantum-well VCSEL microcavity, externally applied electric fields directly perturb intracavity optical modes, enabling modulation pathways beyond conventional carrier–photon-limited operation. Physics-based semi-analytical modeling combined with rigorous full-vector 2.5D Maxwell finite-difference time-domain simulations reveals the emergence of three distinct modulation regimes: a conventional carrier–photon-dynamics-limited regime, a hybrid electro-optic–carrier–photon regime, and a transport-dominated regime characterized by suppressed relaxation-oscillation behavior and a quasi-flat ultrabroadband response. The transition is accompanied by systematic cavity-field redistribution while the dominant cavity resonance remains largely preserved, indicating that modulation enhancement originates from field-controlled transport rather than conventional resonance engineering alone. Representative organized modulation transport states exhibit nearly an order-of-magnitude bandwidth enhancement relative to conventional VCSEL operation and follow an approximate scaling with a reduced geometric transport coordinate. These results establish field-controlled modulation transport as a distinct dynamical regime of semiconductor microcavities, providing a framework for understanding EO-assisted modulation beyond conventional relaxation-oscillation limits and a pathway toward sub-terahertz-class photonic transmitters and future high-density optical interconnect systems.