Silicon photonics highspeed photodiode with dual optical inputs for datacenter applications

The global demand for cloud services and data processing is driving a digital transformation that requires interconnects to be faster, denser, and more energy-efficient. Silicon photonics is the platform of choice for this shift toward Terabit-scale communication, but its integration faces a fundamental challenge: the unpredictable polarization instability of standard optical fibers and the inherent polarization sensitivity of conventional Grating Couplers.
Our research introduces a novel, integrated solution: the Dual-Input Waveguide Integrated Photodiode (DIPD). Designed to seamlessly interface with the two optical outputs of a Polarization-Splitting Grating Coupler (PSGC), and electrically combining the two optical signals which carry the same information. Thus – providing a robust, polarization-insensitive receiver architecture.
Through rigorous design, simulation, and two manufacturing cycles, the DIPD was experimentally validated, demonstrating performance well beyond industry requirements, including high Quantum efficiency (η≈97%) and a large Electro-Optical Bandwidth (EOBW) of ≈58GHz for high power optical inputs.
A key contribution of this work is the experimental identification and mitigation of the Space Charge Effect as the primary bottleneck limiting EOBW under high optical power: by which buildup of photogenerated carriers screens the electric field and degrades highspeed performance. This negative effect is inherently drastically mitigated by the DIPD’s architecture: by distributing the incident optical power across two separate absorption regions, the carrier density is effectively halved, allowing the device to maintain its high bandwidth at significantly higher total signal levels compared to conventional single-input designs.
This work delivers a robust, practical, and scalable polarization-insensitive receiver and provides a generalized design principle for boosting the performance of high-speed photodetectors for next-generation silicon photonic integrated circuits.

M.Sc. student under the supervision of Prof. Emeritus Yael Nemirovsky.