Study Of Backside Chip-fiber Alignment Technique For Superconducting Nanowire Single Photon Detectors

Nowadays,the requirement of quantum measurement is getting higher with the development of quantum technology.However,Superconducting nanowire single photon detector is becoming one of the hottest subjects in quantum measurement with fast response speed,low dark count rate,high detection efficiency,short time jitter and so on.This paper aims to optimize SNSPDs from coupling efficiency and absorption efficiency.Firstly,this paper introduces the principle of Gauss beam and checks its characterization.Then,we analyze the positive incidence of Gauss beam and its application in SNSPDs.Lastly,we research the reflection of SNSPDs by combining transmission matrix and Comsol,and then propose some improved schemes.In addition,this paper also proposes a half-wave plate with ultra wide-band.This half-wave plate is built through a method we called "Mirror-Method",moreover,it has simple structure,wide band and high stability.