Waveguide-integrated Infrared Superconducting Nanowire Single-photon Detector

Superconducting nanowire single photon detector(SNSPD)is a kind of single photon detector(SPD),which is based on the hot spot effect to detect photons.SNSPD is widely used in quantum communication,bio-fluorescence analysis and VLSI CMOS circuit non-contact high-speed test.Waveguide integrated superconducting nanowire single-photon detector was proposed in 2009,and this new structure can achieve the integration of silicon-based devices and SNSPD.What's more,as long as the nanowire is long enough,the device can get about 100% absorption.At present,the research on waveguide integrated SNSPD is focused on the wavelength of 1550 nm.No one has studied the characteristics of a waveguide integrated SNSPD device over a wide spectral range.In addition,with respect to the polarization insensitivity of SNSPD,researches only target on the traditional meander structure.The purpose of this paper is to design and fabricate a waveguide integrated SNSPD with high spectral efficiency in the infrared broadband(1200 nm to 1700 nm)and polarization insensitivity.The research include three parts: the first part is to use COMSOL and MATLAB simulation software to optimize the optical design of the waveguide structure,so that the device can achieve a high absorption efficiency in broadband.The second part is the preparation and characterization of superconducting niobium nitride films.The third part is the processing of waveguide integrated SNSPD.The main achievements of this paper are as follows:1.The waveguide integrated SNSPD based on ultra-narrow(30 nm)nanowires can achieve high absorptance in broadband(1200 nm to 1700 nm)and is polarization insensitive,if the waveguide is longer than 110 mm.2.The NbN superconducting thin films with thickness of about 6 nm and superconducting transition temperature of 10.8 K were sputtered on silicon and silicon dioxide substrates by reactive DC magnetron sputtering.3.The waveguide integrated infrared SNSPD device was fabricated,and the dose of electron beam exposed for nanowires and waveguides was explored.