Very low threshold single quantum well graded-index separate confinement heterostructure InGaAs/InGaAsP lasers grown by chemical beam epitaxy

Abstract

We have succeeded in preparing 1.5 μm wavelength strained-layer graded-index separate confinement heterostructure (GRINSCH) InGaAs/InGaAsP single quantum well (SQW) injection lasers by chemical beam epitaxy (CBE). These lasers have extremely low threshold current density Jth of 170 A/cm2, internal quantum efficiency of 83%, and internal waveguide loss of 3.8 cm−1. To the best of our knowledge, these results represent the best values obtained thus far from long-wavelength InGaAs/InGaAsP quantum well injection lasers grown by any techniques. However, despite the recent rapid reduction in Jth, the threshold-temperature dependence remains poor (T0=45 K) even in these very low Jth GRINSCH SQW lasers.