Dual-Mode Calorimetric Superconducting Nanowire Single Photon Detectors
A dual-operation mode SNSPD is proposed. In the conventional Geiger mode, the sensor operates at temperatures well below the critical temperature, Tc, working as an event counter without sensitivity to the number of photons impinging the sensor. In the calorimetric mode, the detector is operated at temperatures just below TC and displays calorimetric sensitivity in the range of 15 to 250 absorbed-photon energy equivalent for a photon beam with a wavelength of 515 nm. In this energy sensitive mode, photon absorption causes Joule heating of the SNSPD that becomes partially resistive without the presence of latching. Depending on the application, by tuning the sample temperature and bias current using the same readout system, the SNSPD can readily switch between the two modes. In the calorimetric mode, SNSPD recovery times shorter than the ones in the Geiger mode are observed, reaching values as low as 560 ps. Dual-mode SNSPDs may provide significant advancements in spectroscopy and calorimetry, where precise timing, photon counting and energy resolution are required.