Multi-color photon detection with a single superconducting transition-edge sensor

Optical transition-edge sensors (TESs) with high detection efficiency and energy resolution are attractive to applications such as quantum information, astronomy, and biological spectral imaging. In this work, we developed a titanium-based TES with an energy resolution of 0.24 eV at 1520 nm, i.e., a wavelength resolution of 64 nm at 500 nm, aiming at the application of optical/infrared spectrometers without any wavelength multiplexing components. The TES is embedded in an optical cavity consisting of dielectric mirror and antireflection coating, which makes it detect single-photons with no low-energy tails. The dynamic range, extended by calibration with a quadratic function, covers the wavelength range of 400-1600 nm.