Near-unity absorption of near-infrared light in tungsten films

Abstract The number-resolving ability and extremely low dark-count rate of tungsten transition-edge sensors make them excellent candidates to replace avalanche photodiodes in quantum information experiments such as quantum key distribution and quantum computing at the telecommunication wavelengths, 1330 and 1550 nm . Increasing the absorption of these devices from the current value of 20% to near unity would make these detectors even more desirable for these applications. By incorporating the tungsten in a stack of elements including a mirror and an anti-reflective coating, we have demonstrated room-temperature absorption of greater than 97% in films of tungsten.