Broadband Photodetectors as a Versatile Building Block for Photonic Circuits

Scientists at the Max Planck Institute of Microstructure Physics demonstrate broadband integrated photodetectors for visible and near-infrared photonic circuits, featuring low dark currents, high-speed operation, and avalanche mode capability.

To the point:

• Broadband operation: Two integrated photodetector variants together cover a continuous wavelength range from 400 to 955 nm, across the visible and near-infrared.
• Versatility: Low picoamp-scale dark currents, high-speed operation (up to 18 GHz), and avalanche mode capability for low-light-level detection.
• Building block for photonic integration: Implemented in a foundry-fabricated short-wavelength silicon photonics platform on 200 mm wafers.
• Enabling new microsystems: Ongoing work integrates these devices into microsystems under development by Dr. Wesley Sacher’s group for biophotonics, AR/VR smart glasses, and quantum technologies.

Researchers in the group of Dr. Wesley Sacher at the Max Planck Institute of Microstructure Physics, in collaboration with Advanced Micro Foundry, have developed broadband, waveguide-coupled photodetectors in a foundry-fabricated silicon photonics platform for short (submicrometer) wavelengths. The devices consist of silicon nitride (SiN) nanophotonic waveguides coupled to silicon photodetectors, with operation relying on hybrid optical modes shared between the two materials. These modes are engineered through the waveguide dimensions to enable efficient broadband absorption. Published in Optics Express, the work demonstrates two detector variants collectively spanning a wavelength range of 400–955 nm, along with picoamp-scale dark currents, high-speed operation (up to 18 GHz), and avalanche-mode capability, enabling detection of weak optical signals.

In a broader context, short-wavelength (VIS + NIR) silicon photonics is opening doors to miniaturized, scalable optical systems, from biophotonics and sensing to quantum technologies and microdisplays. This work is part of a larger effort within Dr. Sacher’s group to support this breadth of applications with a versatile, foundry-fabricated platform spanning more than an octave in wavelength with high-performance components — thereby reducing the need for individually customized processes. As photodetection is a core functionality in photonic circuits, these results provide a key building block for advanced short-wavelength silicon photonic microsystems.

Ongoing work is integrating these components into photonic circuits for biosensors and implantable neurotechnologies, miniaturized light engines for smart glasses, and quantum photonics.