High-temperature pulsed operation of InGaAsP/InP surface emitting lasers

The observation of above-room-temperature pulsed operation of 1.3- mu m InGaAsP/InP vertical-cavity surface emitting lasers (VCSELs) is reported. Lasing operation was successfully achieved up to temperatures as high as 66 degrees C. The threshold current at 20 degrees C was only 50 mA, which is much lower than that previously reported (150 mA) for VCSELs in this material system. The VCSEL structure is the polyimide-embedded constricted mesa structure with an undercut active layer formed using a selective chemical etchant. The laser cavity consists of a 1.5- mu m-thick p-InP cladding layer, a 0.6- mu m p-InGaAsP active layer, and a 2- mu m n-InP cladding layer grown by MOVPE on a p-type InP substrate.