Detection of Strong Light-Matter Interaction in a Single Nanocavity with a Thermal Transducer.

The concept of strong light-matter coupling has been demonstrated in semiconductor structures, and it is poised to revolutionize the design and implementation of components, including solid state lasers and detectors. We demonstrate an original nanospectroscopy technique that permits the study of the light-matter interaction in single subwavelength-sized nanocavities where far-field spectroscopy is not possible using conventional techniques. We inserted a thin (∼150 nm) polymer layer with negligible absorption in the mid-infrared range (5 μm < λ < 12 μm) inside a metal-insulator-metal resonant cavity, where a photonic mode and the intersubband transition of a semiconductor quantum well are strongly coupled.

Unified Description of Saturation and Bistability of Intersubband Transitions in the Weak and Strong Light-Matter Coupling Regimes.

We propose a unified description of intersubband absorption saturation for quantum wells inserted in a resonator, both in the weak and strong light-matter coupling regimes. We demonstrate how absorption saturation can be engineered. In particular, we show that the saturation intensity increases linearly with the doping in the strong coupling regime, while it remains doping independent in weak coupling.

Fast amplitude modulation up to 1.5 GHz of mid-IR free-space beams at room-temperature.

Applications relying on mid-infrared radiation (λ ~ 3-30 μm) have progressed at a very rapid pace in recent years, stimulated by scientific and technological breakthroughs like mid-infrared cameras and quantum cascade lasers. On the other side, standalone and broadband devices allowing control of the beam amplitude and/or phase at ultra-fast rates (GHz or more) are still missing. Here we show a free-space amplitude modulator for mid-infrared radiation (λ ~ 10 μm) that can operate at room temperature up to at least 1.

III-V on CaF: a possible waveguiding platform for mid-IR photonic devices.

We developed a technique that enables replacement of a metallic waveguide cladding with a low-index (n≈1.4) material - CaF or BaF. It is transparent from the mid-IR up to the visible range: elevated confinement is preserved while introducing an optical entryway through the substrate.

Optically implemented broadband blueshift switch in the terahertz regime.

We experimentally demonstrate, for the first time, an optically implemented blueshift tunable metamaterial in the terahertz (THz) regime. The design implies two potential resonance states, and the photoconductive semiconductor (silicon) settled in the critical region plays the role of intermediary for switching the resonator from mode 1 to mode 2. The observed tuning range of the fabricated device is as high as 26% (from 0.

Coherent control of THz pulses polarization from femtosecond laser filaments in gases.

We demonstrate the possibility to rotate the polarization of linearly polarized THz pulses via the accurate control of the 2-color filament surrounding gas pressure. We also show ways to produce elliptically and circularly polarized THz pulses.