Very low threshold current density 1.3 μm-InAsP/InGaAsP strained quantum well GRINSCH lasers grown by gas source MBE

We report the successful fabrication of the first Gas Source MBE grown InAsP/InGaAsP single and multiquantum well lasers with linearly graded InGaAsP confinement layers. The optical quality of the InAsP/InGaAsP quantum wells (QWs) are investigated by room temperature Photoluminescence (PL) spectroscopy; Intense PL-signal with small FWHM is observed in structures containing five, three and one quantum well indicating that our structures are of high optical quality. Laser structures containing graded confinement layers and various numbers of quantum wells are grown and fabricated into broad-area laser diodes. Threshold current densities of 400 A/cm² 270 A/cm² and 180 A/cm² are obtained for 1.2 mm long lasers containing five, three and single quantum well, respectively. These values are among the lowest ever achieved for 1.3 μm lasers grown by any kind of MBE