2 µm Ghost Spectroscopy with an Integrated Silicon Quantum Photonics Source

Abstract

A ghost spectroscopy measurement with an entangled photon source is demonstrated. The transmission spectrum at the 2 m absorption peak of gaseous carbon dioxide (CO2) is measured in a highly noisy environment. Despite the noise, a high sensitivity is obtained, a value that is larger than the one found for a classical spectroscopy measurement performed in the same conditions. The probe photons are time‐energy correlated photon pairs generated through intermodal spontaneous four‐wave mixing in a silicon waveguide. This observation opens the way to low‐cost on‐chip MIR sensors insensitive to environmental noise.