Towards Integrated Single Photon Avalanche Detectors for Visible Light (Invited)

Integrated avalanche photodetectors (APDs) are essential and ubiquitous devices in quantum photonics applications. While free-space APDs are a mature technology, the development of integrated APDs for visible light is still in its infancy. In this invited talk, we review our work on integrated photodetectors – the Germanium photodetector for O band, and the first integrated silicon (Si) APD for visible light. A unique feature of the integrated Si APD system for visible light is the end-fire coupling between the silicon nitride (SiN) waveguide and the Si APD in the same layer. This allows for broadband and high-efficiency coupling of light from the SiN waveguide to the Si APD for light detection, without the drawbacks of conventional interlayer coupling. Our work on integrated Si APDs based on Geiger-mode and our progress towards achieving single photon detection for visible light is discussed in the talk.