Lowering the energy consumption in silicon photonic devices and systems [Invited]

We review current silicon photonic devices and their performance in connection with energy consumption.Four critical issues are identified to lower energy consumption in devices and systems: reducing the influence of the thermo-optic effect, increasing the wall-plug efficiency of lasers on silicon, optimizing energy performance of modulators, and enhancing the sensitivity of photodetectors. Major conclusions are(1) Mach–Zehnder interferometer-based devices can achieve athermal performance without any extra energy consumption while microrings do not have an efficient passive athermal solution;(2) while direct bonded III–V-based Si lasers can meet system power requirement for now, hetero-epitaxial grown III–V quantum dot lasers are competitive and may be a better option for the future;(3) resonant modulators, especially coupling modulators, are promising for low-energy consumption operation even when the power to stabilize their operation is included;(4) benefiting from high sensitivity and low cost, Ge/Si avalanche photodiode is the most promising photodetector and can be used to effectively reduce the optical link power budget. These analyses and solutions will contribute to further lowering energy consumption to meet aggressive energy demands in future systems.

Athermal scheme based on resonance splitting for silicon-on-insulator microring resonators

A novel athermal scheme utilizing resonance splitting of a dual-ring structure is proposed.Detailed design and simulation are presented,and a proof of concept structure is optimized to demonstrate an athermal resonator with resonance wavelength variation lower than 5 pm∕K within 30 K temperature range.

Single-drive high-speed lumped depletion-type modulators toward 10 fJ/bit energy consumption

Reduction of modulator energy consumption to 10 fJ∕bit is essential for the sustainable development of communication systems.Lumped modulators might be a viable solution if instructed by a complete theory system.Here,we present a complete analytical electro-optic response theory,energy consumption analysis,and eye diagrams on absolute scales for lumped modulators.Consequently the speed limitation is understood and alleviated by single-drive configuration,and comprehensive knowledge into the energy dependence on structural parameters significantly reduces energy consumption.The results show that silicon modulation energy as low as 80.8 and 21.5 fJ∕bit can be achieved at 28 Gbd under 50 and 10 Ω impedance drivers,respectively.A 50 Gbd modulation is also shown to be possible.The analytical models can be extended to lumped modulators on other material platforms and offer a promising solution to the current challenges of modulation energy reduction.