Low loss silicon waveguides for the terahertz spectral region

Chip scale terahertz dielectric waveguides, consisting out of high resistivity silicon as a core material have been fabricated. The waveguide loss is measured to be similar to 1dB/cm at both 1 THz and 2.5 THz

Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia) in gas state. The low-power (<60 mW) laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications

GaAs metal-semiconductor-metal Schottky microwave optical switches

The aim of our work was to integrate Schottky MSM photodetectors in the central strip of coplanar lines for microwave switching application. The MSM photodetectors in the microwave lines have an active surface of 3×3 μm 2 and electrode spacing of 0.2, 0.3, 0.5 and 1 μm. The characterization of the structures in darkness and under illumination allowed us to obtain On/Off ratio of 26-28 dB at 20 GHz and 25 GHz. These results demonstrate that the structures show a good performance for microwave photoswitching which means good insulation in darkness and low insertion losses under illumination

Frequency noise and phase-locking of a quantum cascade laser-pumped, 1.073THz molecular laser using a 1560nm frequency comb

International audienc

Mid-infrared Near-Field Nanoscopy of organic and inorganic samples

Mid-infrared near-field nanoscopy is a new technique that allows to extract interesting informations at the nanoscale. After a short presentation of the technique, some electromagnetic simulations are showed and some examples of images obtained in two different cases are presented