Low-threshold GRIN-SCH AlGaInAs 1.55 mu m quantum well buried ridge structure lasers grown by molecular beam epitaxy

Two-step MBE/MOVPE epitaxy buried ridge stripe GRIN-SCH quantum well lasers having MBE active structure consisting of GaInAs quantum wells and an AlGaInAs continuously graded confinement region have been fabricated and characterised. Devices operating at 1.55 mu m wavelength with a low CW threshold current of 18.7 mA have been demonstrated. This figure is the best result obtained in the AlGaInAs system. A study of the intrinsic optical response of the active layer showed a very fast decay of the resonance oscillations. A good figure of the optical bandwidth move-out rate 3.9 GHz mW^-12/ has been observed.