Integrated avalanche photodetectors for visible light

Salih Yanikgonul,Shawn Yohanes Siew,Ting Hu,Leonid Krivitsky,Victor Leong,Ching Eng Png,Jun Rong Ong

doi:10.1038/s41467-021-22046-x

Abstract

Integrated photodetectors are essential components of scalable photonics platforms for quantum and classical applications. However, most efforts in the development of such devices to date have been focused on infrared telecommunications wavelengths. Here, we report the first monolithically integrated avalanche photodetector (APD) for visible light. Our devices are based on a doped silicon rib waveguide with a novel end-fire input coupling to a silicon nitride waveguide. We demonstrate a high gain-bandwidth product of 234 ± 25 GHz at 20 V reverse bias measured for 685 nm input light, with a low dark current of 0.12 μA. We also observe open eye diagrams at up to 56 Gbps. This performance is very competitive when benchmarked against other integrated APDs operating in the infrared range. With CMOS-compatible fabrication and integrability with silicon photonic platforms, our devices are attractive for sensing, imaging, communications, and quantum applications at visible wavelengths.

Highlights

Integrated photodetectors are essential components of scalable photonics platforms for quantum and classical applications
For integrated avalanche photodetector (APD), besides the photodetection efficiency of the active APD structure, the coupling of input light from the photonic circuit to the APD is critical to the device performance
While conventional integrated APDs rely on an interlayer transition from an input waveguide above or below the APD5,30,31, using the same approach for visible wavelengths would lead to deteriorations in noise and bandwidth performance[15,17]

Summary

Introduction

Integrated photodetectors are essential components of scalable photonics platforms for quantum and classical applications. The majority of recent research in this area has been geared toward applications in optical communications networks, focusing on operation at infrared telecommunications wavelengths These devices have been developed on a variety of material platforms, including III–V semiconductors[4], germanium (Ge)[5,6,7,8,9,10,11], and Si12–17. While conventional integrated APDs rely on an interlayer transition from an input waveguide above or below the APD5,30,31, using the same approach for visible wavelengths would lead to deteriorations in noise and bandwidth performance[15,17] This is due to the much longer coupling length required to achieve efficient coupling at these wavelengths, resulting in device sizes much larger than what is required for efficient photon absorption. A larger device size decreases the bandwidth due to RC limitation, and increases dark noise due to the larger active volume

Methods

Results

Conclusion