Design of Hybrid Plasmonic Multi-Quantum-Well Electro-Reflective Modulators towards < 100 fJ/bit Photonic Links

Realization of on-board and inter-chip optical interconnects requires a photonic data link with power consumption well below their electrical counterparts (i.e. 50 Gb/s requires 2-4 pJ/bit/channel. External reverse-biased modulators could drastically reduce this power consumption. Here we design ultralow power GaAs/AlGaAs multi quantum well electro-reflective modulators operating at 1 V for facile integration with polymer “optical bridges”, utilizing coupled quantum confined Stark effect between adjacent quantum wells and optical coupling to hybrid surface plasmon-slab modes for significantly enhanced extinction ratio and spectral bandwidth. Distinctive from conventional electro-optical or electro-absorption modulators, this new design synergistically leverages ultra-large changes in both refractive index (|δn|∼0.05) and absorption coefficient (α∼10 $-4$ 4 cm $-1$ ), achieving 35-50 dB extinction ratio at 1 V reverse bias with a low insertion loss of 1-3 dB, an incident angle tolerance of ~5°, and a spectral bandwidth of 7-10 nm. The modulator power consumption is ~ 1.9 fJ/bit without the need of thermal tuning, and the RC-limited bandwidth well exceeds 100 GHz. This new modulator enables high bandwidth and ultralow power optical interconnect networks at >100 Gb/s/channel and <100 fJ/bit/channel compatible with ever-scaling CMOS technologies.