Faist is the inventor of the quantum cascade laser (QCL, 1994 at Bell Labs) and leads the Quantum Optoelectronics Group at ETH. Research directions: (1) QCL frequency combs — ring QCLs demonstrate dissipative Kerr solitons in the THz (Science Advances 2023), key for broadband integrated mid-IR spectrometers; (2) Dual-comb spectroscopy — two co-integrated ring QCLs for ultrafast molecular fingerprinting; (3) Quantum cascade detectors — strain-compensated InGaAs/InAlAs QCDs for short-wave mid-IR (<4 µm) sensing; (4) THz strong-coupling — ultrastrongly coupled 2DEG in cavities for quantum photonics; (5) Astrophysical heterodyne receivers — double-metal QCL Josephson mixers. Spin-off: IRsweep (mid-IR dual-comb systems) and Alpes Lasers (QCL commercialisation). FIRST Center head at ETH.

Giessen works on ultrafast nano-optics and plasmonics, plasmonic and metasurface sensors, femtosecond two-photon 3D-printed micro-optics (on fiber tips and detectors), widely tunable ultrafast/mid-IR sources for molecular sensing, and Rydberg-exciton quantum optics in cuprous oxide. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work sits adjacent as a nanophotonic sensing and light-source enabler.

Schuessler combines optical frequency combs with cavity-enhanced and mid-IR spectroscopy for ultrasensitive trace-gas and isotopic detection, and runs ion-trap precision mass/laser spectroscopy of exotic species. In the broader landscape of NV-centre ensemble quantum sensing (DEER, nano-NMR, T1 relaxometry) operating near pT/sqrt(Hz) sensitivity, this work is a comb-metrology counterpart to spin-based chemical sensing.