High power spiral cavity quantum cascade superluminescent emitter.

Quantum Cascade devices with an emission wavelength centered around 5 μm have been shaped into compact, yet long (8 mm and 12 mm) spiral cavities to increase mid-infrared superluminescence (SL) power. Up to ~57 mW of SL power at 250 K is obtained with a Gaussian emission spectrum with a full width at half maximum of 56 cm(-1) and a coherence length of ~107 μm.

Wavelength selection and spectral narrowing of Distributed Bragg Reflector quantum cascade lasers up to peak optical power.

We investigate the impact of Distributed Bragg Reflectors (DBR), ion-milled directly on top of Fabry-Perot type Quantum Cascade (QC) laser ridges, following fabrication and processing of the devices and observe a more than 10-fold reduction in spectral full-width-half-maximum (FWHM) and a maximum of 20dB side-mode suppression ratio (SMSR), maintained to peak optical power. As predicted by our model, and experimentally verified, there is a "sweet-spot" in terms of grating length, ~200 µm on a 3 mm long laser ridge, and a trade-off between spectral narrowing and output power, set by the grating depth, varied from 1.8 to 2.

Standoff photoacoustic detection of explosives using quantum cascade laser and an ultrasensitive microphone.

Standoff detections of explosives using quantum cascade lasers (QCLs) and the photoacoustic (PA) technique were studied. In our experiment, a mid-infrared QCL with emission wavelength near 7.35 μm was used as a laser source.

Sub-parts-per-billion level detection of dimethyl methyl phosphonate (DMMP) by quantum cascade laser photoacoustic spectroscopy.

The need for the detection of chemical warfare agents (CWAs) is no longer confined to battlefield environments because of at least one confirmed terrorist attack, the Tokyo Subway [Emerg. Infect. Dis.