Experimental demonstration of SNSPD-based free space optical communication with a high extinction ratio modulator.

With the development of space technology, the amount of information transmission required by satellites and various spacecraft has increased exponentially. The use of optical communications is a means for future high-speed communications. Adopting superconducting nanowire single photon detectors (SNSPDs) as a receive detector can be capable of detecting signals on the photon scale, which has great application prospects in the field of deep-space optical communication for faint signal detection. However, the use of SNSPDs and high-peak-power optical pulse signals also place higher demands on the extinction ratio of modulators. Therefore, in this paper, we designed a high extinction ratio optical modulator, which adopts cascaded Mach-Zehnder modulators structure, and the static extinction ratio can be reached 77.5 dB. In addition, an SNSPD-based 3.4 km free space optical communication experiment is successfully carried out by using the modulator and a diffuse reflector plate. • A high static extinction ratio optical modulator is designed, and the extinction ratio can be reached 77.5 dB. • SNSPD-based real time FSO experiment is successfully carried out using the modulator and a diffuse reflector plate. • The experiment successfully transmitted live video signals through 3.4 km FSO channels. [ABSTRACT FROM AUTHOR]