Design and realization of a 1.55-μm patterned vertical cavity surface emitting laser with lattice-mismatched mirror layers

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Abstract
It is possible to grow defect-free strained layers on patterned substrates (mesas or grooves) up to thicknesses far exceeding the critical thickness. Defect nucleation and propagation are inhibited in such growth. We have exploited this property to propose a novel InP-based 1.55-/spl mu/m vertical cavity surface emitting lasers (VCSEL's). Careful photoluminescence and transmission electron microscopy (TEM) studies have confirmed that there are no propagating defects in the GaAs/Al/sub x/Ga/sub 1-x/As distributed Bragg reflector (DBR) grown on the patterned InP-based heterostructures, specifically in the multiquantum-well (MQW) region. Lasers were designed with InP/InGaAsP bottom mirrors, InAlAs-oxide current confinement and short-stack GaAs/Al/sub x/O/sub y/ top DBR mirrors. An optimal reflectivity and a maximum wall plug efficiency are determined analytically for this structure. In addition, a theoretical analysis of the modulation response of this device is performed using a rate equation model. Both analyzes show the potential of such a device for implementation in practical designs where high power and modulation bandwidth are required. Lasers with 8-40 /spl mu/m diameter have been fabricated and characterized. A threshold current of 5 mA is observed at 15/spl deg/C for an 8 /spl mu/m diameter device; and up to 60 /spl mu/W of light output is recorded.