The effect of gain saturation in quantum-cascade structures with 2–4 quantum wells per period is herein analyzed on the basis a system balance equations. It shown that nonlinearity parameter decreases an increase relaxation rate laser levels, but total current through structure also increases. use proposed multiphoton designs leads to decrease non-linearity without increasing operating current....

ABSTRACT We present our results on efficient coupling of Quantum Cascade Lasers (QCLs) into Whispering Gallery Resonators, Hollow Waveguide. We also present results of micro sensors using the unique properties of QCLs, e.g. online sensors for Gas Chromatography (GC). We show that because of the unique brightness properties of QCLs, we could improve GC-Infrared sensors' sensitivity to the same l...

A fully quantum-mechanical model for carrier scattering transport in semiconductor intersubband devices was applied to modelling of carrier dynamics in quantum cascade lasers. The standard model uses the envelope function and effective mass approximations to solve electron band structure under an applied bias. The k ·p model has been employed in p-type systems where the more complex band struct...

A terahertz quantum cascade laser is presented in which selectively placed pure AlAs barriers are used to reduce parasitic leakage currents to the conduction band continuum. The design is demonstrated to have improved temperature performance over a regrowth of the current Tmax 200 K record holder (181 K vs. 175 K). Strangely, it fails to lase below 70 K, which we attribute to negative different...

Milliwatt average power terahertz quantum cascade lasers (THz-QCLs) combined with microbolometer focal plane array cameras allow for acquisition rates on the order of 1×10 6 pixels/s. This system enables real-time imaging in transmission and reflection modes with signal to noise ratios of >25 dB per pixel. While these system allow rapid imaging for fairly transparent samples, signal to noise ra...

Quantum cascade lasers provide some of the highest output powers available for light in the mid-infrared range (from 3 to 8 μm). As many of their applications require portability, designs that have a high wall-plug efficiency are essential, and were designed and grown by others to achieve this goal. However, because a large fraction of these devices did not operate at all, very few of the stand...