VERY LOW THRESHOLD SINGLE QUANTUM-WELL GRADED-INDEX SEPARATE CONFINEMENT HETEROSTRUCTURE INGAAS/INGAASP LASERS GROWN BY CHEMICAL BEAM EPITAXY

We have succeeded in preparing 1.5-mu-m 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 J(th) 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 J(th), the threshold-temperature dependence remains poor (T0 = 45 K) even in these very low J(th) GRINSCH SQW lasers.