The Role of Carrier Diffusion in RNGH Instabilities of Quantum Cascade Lasers

Quantum Cascade Laser (QCL) structures exhibit features of multimode Risken-Nummedal-Graham-Haken (RNGH) instabilities [2,3] at low excess above lasing threshold, at pth2 ~ 1.1 [1]. The onset of such RNGH instabilities and excitation of regular self-pulsations may provide practical means to produce picosecond pulses in the MIR spectral range. However, conditions that would trigger such QCL dynamics have not been elucidated so far and these conditions cannot be inferred from conventional laser diodes (LDs), in which RNGH instabilities have not been observed in experiment