The room temperature operation of InAs∕AlSb quantum cascade lasers is reported. The structure, grown by molecular beam epitaxy on an InAs substrate, is based on a vertical transition design and a low loss n+-InAs plasmon enhanced waveguide. The lasers emitting near 4.5μm operate in pulse regime up to 300K. The threshold current density of 3.18-mm-long lasers is 1.5kA∕cm2 at 83K and 9kA∕cm2 at 300K.

No abstract

No abstract

Downsizing and compatibility with MEMS silicon foundries is an attractive path towards a large diffusion of photoacoustic trace gas sensors. As the photoacoustic signal scales inversely with the chamber volume, a trend to miniaturization has been followed by several teams. We review in this article the approach initiated several years ago in our laboratory. Three generations of components, namely a 40 mm 3 3D-printed cell, a 3.7 mm 3 silicon cell, and a 2.3 mm 3 silicon cell with a builtin piezoresistive pressure sensor, have been designed. The models used take into account the viscous and thermal losses, which cannot be neglected for such smallsized resonators. The components have been fabricated either by additive manufacturing or microfabrication and characterized. Based on a compilation of experimental data, a similar sub-ppm limit of detection is demonstrated. All three versions of photoacoustic cells have their own domain of operation as each one has benefits and drawbacks, regarding fabrication, implementation, and ease of use.

No abstract

No abstract

The advantages and drawbacks of the different semiconductor materials which can be used for the fabrication of quantum cascade laser (QCL) emitting in the 3–4μm wavelength range bring us to propose a material combination which can be lattice matched to InAs substrate. It is shown that using InAs quantum wells and AlAsSb barriers, it is possible to balance the strain in QCL structures made on InAs whatever the active region design and the wavelength targeted. A first InAs∕AlAsSb QCL structure has been grown and fully characterized by x-ray diffraction. The devices emit at 3.5μm at 300K in pulsed mode.

Articles you may be interested inLoss mechanisms of quantum cascade lasers operating close to optical phonon frequencies