Superconducting Nanowire Single Photon Detectors (SNSPDs) properties and LIDAR applications

Light detection and ranging (Lidar), is a remote sensing technique used for the analysis of the atmosphere. The wavelength λ used in the Lidar affects the maximum reachable distance, the safety and the specific aerosol or molecule to be observed and moving to IR domain would give a positive contribute to a significant enhancement in all directions. Anyway, an upper limit is set by detectors signal to noise ratio which becomes very low as the wavelength passes 1μm. In this scenario, Superconducting Nanowire Single Photon Detectors (SNSPD) are the best candidates for the realization of a Lidar measurement in IR domain. Indeed, SNSPDs have high detection efficiency, low noise, low dead time, high maximum counting rate and good SNR up to λ=5μm. This work of thesis was mainly devoted to the realization of a Lidar measurement with an SNSPD at λ>1μm. In order to do that, a portable cryogenic measurement setup was realized and tested as well as the readout electronics and acquisition programs. Also different superconducting materials (NbN, NbTiN, MoSi, NbRe) and geometries have been explored, resulting in the optimization of the fabrication processes. A detailed study of dark counts generation mechanism was carried on and a deeper understanding of non-equilibrium in the superconductor was reached. The results of a Lidar measurement with SNSPD at 1064nm are presented as well as the preparation of an aerosol measurement at 1550nm. Part of this work was realized at A.l.a. S.r.l. laboratories (Naples, Italy) and Beijing Research Institute of Telemetry (Beijing, PRC)