Periodic index separate confinement heterostructure InGaAs/AlGaAs multiple quantum well laser grown by organometallic vapor phase epitaxy

Organometallic vapor phase epitaxy was used to grow a novel periodic index separate confinement heterostructure (PINSCH) InGaAs/AlGaAs multiple quantum well (MQW) laser. Secondary ion mass spectrometry and transmission electron microscopy were used to characterize the structure. The performance of the PINSCH laser was compared with that of a graded index separate confinement heterostructure (GRINSCH) MQW laser grown under similar conditions. The PINSCH laser uses cladding layers comprised of periodic semiconductor multilayers ( Ala,Ga0.6As/GaAs) which provide both optical and electrical confinement. Since the optical field decays over several multilayers, and therefore is far less tightly confined than in the GRINSCH structure, a significant reduction of the transverse far-field angle occurs. Comparing the performance of 5 X 750 p’rn self-aligned ridge waveguide InGaAs/AlGaAs lasers emitting at 980 nm, the PINSCH structure exhibits a transverse far-field angle of 23” compared to 46” for the GRINSCH. This is obtained at the expense of a modest increase in threshold current ( 19 mA vs 10 mA).