Very Low Threshold InGaAsP Mesa Laser

Abstract-Very low threshold currents InGaAsP/InP terrace mesa (T-ME) lasers with an unpassivated surface have been fabricated on semi-insulating (SI) InP substrates. Fabrication of the lasers involves a single-step liquid phase epitaxial (LPE) growth and a simple etching process. Lasers operating in the fundamental transverse mode with threshold currents as low as 6.3 mA (for a cavity length of 250 pm) have been obtained. Comparison between the unpassivated lasers and those passivated using the mass transport technique is described. I T has long been suspected that in semiconductor lasers with buried active regions there exists a substantial amount of leakage current bypassing the active region junction through the cladding burying layers. Such a leakage would give rise to an undesirable increase in threshold and possibly to a reduced quantum efficiency. In the case of InCaAsP/InP buried het-erostructure lasers, there have been experimental indications of such leakage currents despite the presence of a reverse bi