Low threshold current AlGaAs/GaAs distributed feedback laser grown by two‐step molecular beam epitaxy

AlGaAs/GaAs distributed feedback lasers with oxide‐stripe structure were fabricated by two‐step molecular beam epitaxy (MBE) growth for the first time. The large coupling coefficient of 90 cm−1 was obtained by controlling precisely the thickness of each layer. As a result, the threshold current of 165 mA, which is the lowest ever reported, was obtained at room temperature. The characteristic temperature T0 was as high as 210 K. Single longitudinal mode oscillation over the temperature range of 50 K was observed without mode hopping. Due to the uniformity of the thickness and composition of the layers grown by MBE, uniform oscillation wavelengths were observed.