Self-aligned coupled cavity GaAs/AlGaAs midinfrared quantum-cascade laser

A monolithic GaAs/AlGaAs quantum-cascade laser with self-aligned focused io n beam-cut coupled cavities, emitting in the range of lambda=9.4 mu m is de monstrated. Separate pulsing of two optically coupled laser sections enable s control of the lasing in single-mode and in multimode regimes. Side mode suppression ratios better than 25 dB are shown. Mode control over two singl e modes spaced by 3.6 cm(-1) is presented. An optical output intensity modu lation in a range of 20 dB is achieved. The laser exhibits a peak output po wer in the range of 180 mW at cryogenic temperatures. The observed mode spa cing is in a good agreement with the calculation. (C) 2000 American Institu te of Physics. [S0003-6951(00)02734-0].