Potential of a Superconducting Photon Counter for Heterodyne Detection at Telecommunication Wavelength

TL;DR

This paper demonstrates a superconducting nanowire detector operating as a mixer at 1550 nm, achieving near-quantum noise limited sensitivity with wide bandwidths, enabling potential development of photon counting heterodyne systems.

Contribution

It introduces a superconducting nanowire single-photon detector functioning as a heterodyne mixer at telecommunication wavelengths, with significant bandwidth and low power requirements.

Findings

Achieved gain bandwidths of 65 MHz and 140 MHz for different device sizes.

Operated at quantum noise limited sensitivity with minimal local oscillator power.

Potential for developing photon counting heterodyne systems with megapixel arrays.

Abstract

Here, we report on successful operation of a NbN thin film superconducting nanowire single-photon detector (SNSPD) in a coherent mode (as a mixer) at the telecommunication wavelength of 1550 nm. Providing the Local Oscillator power of the order of a few picowatts, we were practically able to reach the quantum noise limited sensitivity. The intermediate frequency gain bandwidth was limited by the spectral band of single-photon response pulse of the detector, which is proportional to the detector size. We observed gain bandwidth of 65 MHz and 140 MHz for 7x7 um^2 and 3x3 um^2 devices respectively. Tiny amount of the required Local Oscillator power and wide gain and noise bandwidths along with the needless of any Low Noise Amplification opens possibility for a photon counting heterodyne-born megapixel array development.