Innovative superconducting strip photon detector unveiled

The National Institute of Information and Communications Technology (NICT) in Japan has developed a novel structure in a superconducting strip photon detector that enables efficient photon detection even with a wide strip. The superconducting wide-strip photon detector (SWSPD) features a strip that is over 200 times wider than that of the conventional superconducting nanoStrip photon detectors (SNSPDs). This technology can be used to address the challenges of low productivity and polarisation dependence in conventional SNSPDs.

The new SWSPD can be applied into various advanced technologies such as quantum information communication and quantum computers. Photon detection technology is a strategic core technology to bring about innovations in fields such as quantum information communication, quantum computing, deep space optical communication and laser sensing. The SNSPD developed by NICT has a strip width of 100 nm or less, with researchers demonstrating its usefulness by applying it to quantum information communication technology. However, the fabrication of SNSPDs requires the formation of nanostrip structures using advanced nanofabrication technology, which can cause variations in detector performance and hinder productivity improvement. The presence of polarisation dependence due to the superconducting nanostrip meandering structure also limits the application range for the photon detector.

The researchers developed a novel structure called a ‘high critical current bank (HCCB) structure’ that enables efficient photon detection even if the strip width is widened in the superconducting strip photon detector, and succeeded in developing an SWSPD with a width of 20 micrometres. The nanostrip type required the formation of extremely long superconducting nanostrips with a strip width of 100 nm or less; the wide strip type can now be formed with only a single short straight superconducting strip.

The SWSPD does not require nanofabrication technology and can be fabricated by highly productive general-purpose photolithography technology. Since the strip width is wider than the incident light spot irradiated from the optical fibre, it is possible to eliminate the polarisation dependence in the nanostrip type detector.

This achievement will enable the fabrication of photon detectors with greater productivity and superior features compared to current types of nanostrips. The researchers plan to further explore the HCCB structure in the SWSPD, to detect photons with high efficiency in the telecommunication wavelength band and also in a wide wavelength band from the visible to the mid-infrared.

The research findings were published in the journal Optica Quantum.

Image caption: Developed Superconducting Wide-Strip Photon Detector (SWSPD). Image Credit: National Institute of Information and Communications Technology (NICT).