Growth and fabrication of high-performance 980-nm strained InGaAs quantum well lasers using novel hybrid material system of InGaAsP and AlGaAs

In this paper, we report on the design, growth and fabrication of 980 nm strained InGaAs quantum well lasers employing novel material system of Al-free active region and AlGaAs cladding layers. The use of AlGaAs cladding instead of InGaP provides potential advantages in laser structure design, improvement of surface morphology and laser performance. We demonstrate an optimized broad-waveguide structure for obtaining high power 980 nm quantum well lasers with low vertical beam divergence. The laser structure was grown by low-pressure metalorganic chemical vapor deposition, which exhibit a high internal quantum efficiency of approximately 90% and a low internal loss of 1.5 - 2.5 cm-1. The broad-area and ridge-waveguide laser devices are both fabricated. For 100 micrometers wide stripe lasers with cavity length of 800 micrometers , a low threshold current of 170 mA, a high slope efficiency of 1.0 W/A and high output power of more than 3.5 W are achieved. The temperature dependences of the threshold current and the emitting spectra demonstrate a very high characteristic temperature coefficient (T0) of 200 - 250 K and a wavelength shift coefficient of 0.34 nm/ degree(s)C. For 4 micrometers - width ridge waveguide structure laser devices, a maximum output power of 340 mW with COD-free thermal roll-over characteristics is obtained.