GaInAsP/InP surface-emitting laser diode

Abstract

In this review paper, we will introduce the advantages and laser characteristics of GaInAsP/InP surface-emitting (SE) lasers. In order to obtain the room temperature oscillation of the SE laser diodes, it is very important to reduce not only its threshold current density but also threshold current itself. To decrease its threshold current density and/or its threshold current, we investigated some possible SE laser structures. First, we tried to reduce the threshold current density by introducing (i) a Au/SiO2 mirror, (ii) a dielectric multilayer mirror to increase the n-side (output-side) reflectivity, and (iii) multi-active-layer structure. Next, to reduce the threshold current, certain types of current confining structure, namely (i) a round-high-mesa/polyimide-buried structure, (ii) a planar buried heterostructure (PBH), (iii) a circular buried heterostructure (CBH) with SiO2 mask and (iv) a flat surface circular buried heterostructure (FCBH), were investigated. The threshold current of the SE laser was reduced to 18 mA and its highest operation temperature was raised to 263 K (−10°C).