Quantum cascade

Figure 7.4. Electron micrograph of the cross-section of a quantum cascade semiconductor laser...

A new type of high sensitivity mid-IR detector for single wavelengths is based on an inverted QCL-principle (QCD, quantum cascade detector), but these are still under development and not yet commercially available. 

R. Maulini, M. Beck, J. Faist, E. Gini, Broadband tuning of external cavity bound-to-continuum quantum-cascade lasers. AppZ. Phys. Lett, 84 (10) 1659 (2004). 

I. Howieson, E. Normand, M.T. McCulloch, Quantum-cascade lasers smell success. Laser Focus World, 41(3) S3... 

FIGURE 3.12 The layers of an active region of a quantum cascade laser. 

Fig. 21 Experimental setup for quantum cascade laser (QCL)-HWG gas sensing [92]...

The finite decoherence time is due to some inelastic scattering mechanism inside the system, but typically this time is shorter than the energy relaxation time re, and the distribution function of electrons inside the system can be nonequilibrium (if the finite voltage is applied), this transport regime is well known in semiconductor superlattices and quantum-cascade structures. 

Jerome Faist, Federico Capasso, Carlo Sirtori, Deborah L. Sivco, and Alfred Y. Cho, Quantum Cascade Lasers Federico Capasso, Carlo Sirtori, D. L. Sivco, and A. Y. Cho, Nonlinear Optics in Coupled-Quantum- Well Quasi-Molecules... 

D. Wiedmann, Mid-infrared trace-gas sensing with a quasi-continuous-wave Peltier-cooled distributed feedback quantum cascade aser,Appl. Phys. B (79), 907-913 (2004). 

Charlton C, Temelkuran B, Dellemann G, Mizaikoff B (2005) Midinfrared sensors meet nanotechnology Trace gas sensing with quantum cascade lasers inside photonic band-gap hollow waveguides. Appl Phys Lett 86 194102... 

Gas phase component concentrations A number of standard gas analysers are routinely available for determination of gaseous mixing ratio of CH4, CO, O3, NO, NO2 and SO2 at moderate atmospheric concentrations. GC determination of a limited number of NMHC species is also available for appropriate experiments. An Aerodyne Quantum Cascade Tunable Diode Laser Absorption Spectrometer (QC-TDLAS) is periodically available for NH3 measurements using tiie line at 967 cm and for NO2 measurement at 1606 cm . There are several potential experiments which may benefit from measurement of other trace species. The Differential Optical Absorption Spectrometer (DOAS) described below may be used for determination of lO, OIO, BrO, NO3, HCHO, SO2 and other trace species. 

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