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., <; <; 1 pJ/bit). Currently, directly modulating 850 nm vertical cavity surface emitting lasers at >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 (Δα~10
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.