Micro-nano fiber coupled superconducting nanowire single photon detector was successfully developed

[China Instruments Network Instrument Development] Superconducting nanowire single-photon detector (SNSPD) is a high performance single photon detector that has been widely used in quantum information, laser radar, deep space communications, etc. The field has strongly promoted the development of science and technology in related fields.

Micro-nano fiber coupled superconductor nanowire single photon detector schematic

There are two kinds of optical coupling methods for SNSPD devices. One is vertical optical coupling. The end faces of optical fibers are parallel to the photosensitive surface of SNSPD. Photons are perpendicularly incident on the nanowires. The optical cavity or mirror structure is used to achieve efficient optical coupling. Using this kind of coupling structure, the Shanghai Institute of Microsystem and Information Technology of the Chinese Academy of Sciences has achieved a detection efficiency of NbN-based SNSPD system exceeding 90%, and the relevant results have received widespread attention at home and abroad after publication. The optical coupling structure is characterized by high optical coupling efficiency, but it is limited by the optical coupling structure and the operating wavelength range is limited. Another type of optical coupling is waveguide optical coupling, where nanowires can be fabricated on optical waveguides to achieve efficient intrinsic absorption. However, the coupling efficiency of the optical fiber to the waveguide is low, so that such devices can only be used as an on-chip photonics solution and cannot be used as an independent single photon detector.

The team of Yu Lixing, a researcher of the Shanghai Institute of Microsystems/Chinese Academy of Sciences Superconductivity Excellence Innovation Center, teamed up with professors Fang Wei and Tong Limin of Zhejiang University to propose a micro-nano fiber coupled SNSPD device structure for the first time. This structure places the SNSPD device in the evanescent field of a micro-nanofiber, enabling photon absorption by nanowires in micro-nanofibers. Optical calculations show that this type of structure is expected to achieve high absorption efficiency while maintaining a good wide-spectrum characteristic. After nearly three years of experimentation and exploration by Dr. Jun Wei from Shanghai Microsystems and Dr. Xu Yingxin from Zhejiang University, the research team developed micro-nano fiber-coupled SNSPD devices. At the 1550 nm/1064 nm operating wavelength, the system detection efficiency reached 20%/50%, respectively. The related results were recently published on Optics Express, and the results are expected to open up new research directions in the field of new SNSPD devices and micro-nanofibers.

The research work was supported by the National Key R&D Program “High-performance Single Photon Detection Technology”, the Chinese Academy of Sciences Strategic Leading Science and Technology Project (B) “Basic Research on the Application of Superconducting Sub-devices”, the Natural Science Foundation, and the Shanghai Science and Technology Commission.

(Title: Micro-nano fiber coupled superconducting nanowire single photon detector developed by Shanghai Microsystems)