The effects of injector doping densities on lasing properties of InP-based quantum cascade lasers at 4.3 μm

Abstract

Effects of the injector doping densities on lasing properties of mid-infrared InAlAs–InGaAs–InP quantum cascade lasers at 4.3μm have been studied. Lasers with different average injector doping between 1.29E17cm−3 and 2.07E17cm−3 have been grown by gas source molecular beam epitaxy (GSMBE), and their lasing characteristics were investigated. Lasers with low doped injectors (1.68E17cm−3) exhibited lower threshold current density, longer emission wavelength and lower characteristic temperature T0. The lower injector doping density decreases waveguide loss. On the other hand, the high doping of the injector increases heat transfer through phonon in QCL active region, and thus results in high characteristic temperature T0.