Single-Chip 1.024 Tb/s Optical Receiver for High-Speed Optical links
Integrated optical transceivers, utilizing wavelength-division-multiplexing, offer a path forward for implementation of compact, high-bandwidth and energy-efficient interconnects for future data centers. Here we report the demonstration of a monolithically integrated optical receiver in 45nm CMOS, where efficient multi-layer optical demultiplexing with capacitive tuning, energy efficient electronics and wideband inverse designed grating couplers enable implementation of a 32-channel receiver chip based on wavelength-division multiplexing. The chip operates at an aggregate data-rate of 1.024 Tb/s with all channels operating simultaneously at a data-rate of 32 Gb/s/channel achieving a record energy efficiency of 71 fJ/b, including the power consumption of both the electronic circuitry and the tuning and control of photonic devices, and a record bandwidth density of 4 Tb/s/mm2. The receiver achieves a bit-error-rate below 1E-12 without requiring equalization, error correction or digital processing. Inverse-designed broadband grating couplers provide efficient, low-loss optical coupling into the chip. An on-chip demultiplexer, composed of Mach-Zehnder interferometers (MZIs) and ring resonators, offers a large channel-to-channel isolation sufficient for error-free operation. Capacitive phase shifters embedded within the ring resonators of the demultiplexer are used for wavelength alignment at a zero static power consumption. MZIs and ring-resonators are periodically selected and autonomously locked to the wavelength of the corresponding optical carrier. The implemented monolithic receiver offers a scalable, energy-efficient and reliable solution for the beyond Tb/s optical interconnects.