MBE-grown long-wavelength interband cascade lasers on InAs substrates

An interband cascade (IC) laser structure with an emission wavelength designed to be near 11 μm was grown by molecular beam epitaxy on an InAs substrate. Defects and surface smoothness, as well as the overall crystalline quality, were characterized by optical microscopy, atomic force microscopy and X-ray diffraction. The maximum operating temperatures of a broad-area IC laser device in CW and pulsed modes were 97 K and 130 K, respectively, at an emission wavelength of 11 μm, which is the longest wavelength among interband lasers based on III-V semiconductor materials. The pulsed threshold current density at 80 K was measured to be 72 A/cm². The performance of this IC laser device may be limited by intersubband absorption loss in the active region and an unidentified carrier leakage channel.