Integrated waveguide photodetectors for visible light
In a paper published in Nature Communications, scientists at the Max Planck Institute of Microstructure Physics, Halle have demonstrated broadband, high-efficiency silicon nitride-on-silicon waveguide photodetectors that are monolithically integrated with visible light photonic circuits.
Photonic integrated circuits (PICs) are microchips that manipulate light at the micrometer and nanometer length scales. They are often designed for and used in the infrared wavelengths for fiber optic communications. Poon’s department has been developing PICs that are made with microelectronics processes in a foundry that operate at shorter wavelengths, in the visible spectrum. Visible-light PICs can transform emerging applications in sensing, displays, quantum technology, and neurotechnology by miniaturizing the components into microchips. In this paper, Poon’s team reports an efficient photodetector for PICs that operates broadly across the visible spectrum - from blue to red light. Photodetectors, which convert optical signals into electrical signals, are essential building blocks in PICs. This demonstration shows that it is possible to form good performance photodetectors with PICs. The simple fabrication process and high efficiency make the photodetectors attractive for visible spectrum PICs.
Abstract of the Publication
Visible and near-infrared spectrum photonic integrated circuits are quickly becoming a key technology to address the scaling challenges in quantum information and biosensing. Thus far, integrated photonic platforms in this spectral range have lacked integrated photodetectors. Here, we report silicon nitride-on-silicon waveguide photodetectors that are monolithically integrated in a visible light photonic platform on silicon. Owing to a leaky-wave silicon nitride-on-silicon design, the devices achieved a high external quantum efficiency of >60% across a record wavelength span from λ ~ 400 nm to ~640 nm, an opto-electronic bandwidth up to 9 GHz, and an avalanche gain-bandwidth product up to 173 ± 30 GHz. As an example, a photodetector was integrated with a wavelength-tunable microring in a single chip for on-chip power monitoring.