Abstract:

Quantum cascade lasers (QCL¡¯s) are semiconductor lasers composed of nanometers thick layers of semiconductor materials, and emit light through intersubband transitions in the quantum confined states of the conduction band. The mid-infrared (MIR) QCLs emit at wavelengths ranging from 3 to 15 ?m, which cover the ¡°fingerprint¡± region for most of the gas molecules. The dynamic analysis of QCLs is important for ultra-short pulse generations in the MIR region for trace-gas detection. The unique combination of giant nonlinearities and ultrafast carrier dynamics of QCLs makes the dynamic behavior of QCLs very different from conventional semiconductor lasers. This talk will present the analysis procedure on phase instability and amplitude instability of QCLs. The phase instability exhibits the single-mode nature and the amplitude instability is the multi-mode Risken-Nummedal-Graham-Haken (RNGH) kind of instability. Effects from various nonlinear processes, such as the saturable absorber effect, self-phase modulation, and the spatial hole burning effect, on the instability mechanisms in QCLs will also be discussed.
 
 
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