Time: 10:30 hrs

Location: Room F

Recently, we have demonstrated that the “intrinsic” linewidth of Quantum Cascade Lasers (QCLs) can go beyond the radiative lifetime of the upper level [1]. This represents the first demonstration of a sub-radiative
linewidth for any laser. The intrinsic linewidth of a QCL can be as narrow as hundreds Hz, paving new ways for ultra-sensitive and precise harnessing and detection of molecules. We are working towards full exploitation of such intrinsic properties by designing appropriate phase-lock loops and enhancement-cavities for interaction with molecules. Combination with optical-frequency-comb-synthesizers and appropriate spectroscopic techniques, like saturated-cavity-ringdown-SCAR [2] or polarization spectroscopy [3] can provide unprecedented sensitivity and frequency accuracy for molecular detection. The first advances in the frequency noise characterization of THz QCLs will also be presented.

[1] S. Bartalini et al., “Observing the Intrinsic Linewidth of a Quantum-Cascade Laser:
Beyond the Schawlow-Townes Limit”, Phys. Rev. Lett. 104, 083904 (2010).
[2] G. Giusfredi et al., “Saturated-Absorption Cavity Ring-Down Spectroscopy”, Phys. Rev. Lett. 104,
110801 (2010).
[3] S. Bartalini et. al., “Doppler-free polarization spectroscopy with a quantum cascade laser at 4.3 μm”,
Opt. Express 17, 7440 (2009).