Characteristics Of Photon Number Resolving Superconducting Transition-edge Sensors

As a new field of astronomy,infrared astronomy has become an important branch of contemporary astronomy.It has played an important role in cutting-edge scientific research,such as the observation of low-temperature and hidden celestial bodies,the study of astrophysical and chemical properties and the tracing of the evolution of the early universe.For infrared imaging and spectral sky survey detection of weak optical signals from distant celestial bodies,an infrared single photon detector with high sensitivity and high efficiency is needed.In addition,in the frontier scientific fields such as quantum communication,the demand for high-performance single photon detectors is also growing.Superconducting transition-edge single photon detector(TES)is a new type of superconducting single photon detector.Compared with traditional semiconductor single photon detector,superconducting transition-edge single photon detector has high detection efficiency and low dark counting rate in near-infrared and visible light bands.In particular,superconducting transition-edge single photon detector has excellent photon number resolution.The research on superconducting transition-edge single photon detector abroad started early and developed relatively mature.At present,the domestic research on superconducting transition-edge single photon detector is still in its infancy.Facing the future applications in frontier fields such as infrared astronomical observation,quantum science and biological imaging,the physical model and high detection efficiency characteristics of superconducting transition-edge single photon detector still need to be further analyzed and explored.Based on the above background,this paper focuses on the characteristics of superconducting transition-edge single photon detector,and carries out the following research:Based on the phase slip theory of superconducting thin films,the calculation tool of superconducting TES model based on classical two fluid theory is explored.Through the continuous processing of the phase slip number in the phase slip theory,the key parameters of superconducting TES:resistance temperature sensitivity coefficient a and resistance current sensitivity coefficient β are fitted by using the classical two fluid theory formula,the DC characteristics,heat capacity,thermal conductivity and response characteristics of superconducting transition-edge single photon detector are completely characterized.Based on the calculation tool of superconducting TES model of classical two fluid theory,the superconducting transition-edge single photon detector with different sizes is analyzed and compared,and the parameters of titanium superconducting transition-edge single photon detector such as electron-phonon coupling coefficient,heat capacity coefficient and energy conversion efficiency are obtained;The variation trend of response time and energy resolution of superconducting transition-edge single photon detector with superconducting transition temperature and bias point is calculated,and the performance limit of superconducting transition edge single photon detector is predicted.The factors affecting the detection efficiency of superconducting transition-edge single photon detector are explored.Focusing on the front alignment coupling of single-mode optical fiber,the limit parameters of optical fiber coupling are calculated theoretically.Through a two-dimensional displacement platform combined with inverted infrared microscope imaging,a stable and reliable high-efficiency device packaging method is obtained;An optical cavity for 1550 nm wavelength is designed and prepared,and the influence of the optical cavity on the characteristics of superconducting thin films is explored;The loss in the optical fiber path is optimized,and the detection efficiency of the system is improved to more than 90%.The noise and dark counting rate characteristics of superconducting transition-edge single photon detector are investigated.The theoretical and measured noise levels are compared and analyzed.The theoretical energy resolution is calculated from the measured noise spectrum,which is consistent with the measured results;The influence of stray light and black-body radiation on the dark counting characteristics of superconducting transition-edge single photon detector is explored.Combined with theoretical analysis and comparative experiments,the generation of dark counts is suppressed by means of room temperature optical fiber shielding and low temperature optical fiber winding,and the dark counting rate below 100 Hz is realized.