Single-photon spectroscopy of SiNx using an integrated SSPD

The work describes the use of a superconducting NbN detector for spectroscopy of an optical SiNx waveguide at cryogenic temperatures at single-photon power of the incident radiation in the S-, C-, and L-bands. The technological process of creating the superconducting detector on the planarized surface of a protective SiO2 layer over the SiNx optical waveguide is described. The transparency window of SiNx around 1550 nm was demonstrated as an increase in the number of optical counts of the detector.