Quantum and interband cascade lasers between classical and quantum operation regime

Our work investigates the generation of non-classical light by cascade lasers in the mid-infrared (MIR, 3–5μm) spectral region. Using a MIR-balanced detector sensitive to the intensity noise below the classical level, we demonstrated shot-noise-limited operations of MIR cascade lasers. The same setup was exploited to measure four-wave-mixing-induced correlations between modes in harmonic combs emitted by these devices. Moreover, we recently tested the electron-to-photon noise transfer function in cascade lasers, paving the way to control their emissions down to the quantum level. These novel insights should make laser sensing possible at unprecedented sensitivity levels.