14 mu m quantum cascade lasers based on diagonal transition and nonresonant extraction

We report InP-based room-temperature high-average-power quantum cascade lasers emitting at 14 mu m. Using a novel active region design, a diagonal bound-to-bound lasing transition is guaranteed by efficient electron injection into the upper laser level and fast nonresonant electron extraction through a miniband from the lower laser level. For a 4 mm long and 40 mu m wide double channel ridge waveguide laser with 55 stages of the active region, the threshold current density is only 3.13 kA/cm(2) at room temperature. At 293 K, the maximum single facet peak power and average power are up to 830 mW and 75 mW, respectively. The laser exhibits a characteristic temperature T-0 of 395 K over a temperature range from 293 to 353 K. (C) 2019 Chinese Laser Press