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 (Formula presented.) m absorption peak of gaseous carbon dioxide (CO2) is measured in a highly noisy environment. Despite the noise, a high sensitivity (Formula presented.) (Formula presented.) 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.