We present InAs/AlSb quantum cascade lasers (QCLs) monolithically integrated on an on-axis (001) Si substrate. The lasers emit near 8 μm with threshold current densities of 0.92–0.95 kA/cm2 at 300 K for 3.6-mm-long devices and operate in pulsed mode up to 410 K. QCLs of the same design grown for comparison on a native InAs substrate demonstrated a threshold current density of 0.75 kA/cm2 and the same maximum operating temperature. The low threshold current density of the QCLs grown on Si makes them suitable for photonic integrated sensor implementation.

Indium arsenide (InAs)-based quantum cascade lasers (QCLs) operating close to 25 µm are reported. Thick n-doped InAs cladding layers were used for optical confinement. Fabry-Perot lasers exhibited a threshold current density as low as 1.1 kA/cm 2 in pulsed mode at 80 K. The lasers operated in this regime up to 240 K, where the threshold current density increased up to 1.7 kA/cm 2. These are the lowest threshold current densities for QCLs operating above 20 µm.

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The InAs/AlSb quantum cascade lasers (QCLs) operating ∼11 µm in the continuous wave (cw) regime at room temperature are reported. The lasers with cleaved Fabry-Perot resonators demonstrated pulsed threshold current densities below 1 kA/cm 2 at 300 K and operated in a cw up to 320 K that is the maximum temperature of such regime of operation for InAs-based QCLs. Distributed feedback lasers fabricated from the same wafer exhibited single frequency emission near 11 µm and operated in the cw regime up to 295 K.