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Improvement of Current Injection Uniformity and Device Resistance in Long-Wavelength Vertical-Cavity Surface-Emitting Laser Using a Tunnel Junction

A uniform current injection is important in long-wavelength vertical-cavity surface-emitting lasers (VCSELs) for low-threshold, high-efficiency, and stable-mode operation. The utilization of a tunnel junction can solve these problems by employing an n-type highly conductive material for an anode. In this study, the electrical property of a long-wavelength VCSEL with a tunnel junction is analyzed using an equivalent circuit model. The optical absorption loss of a tunnel-junction-embedded VCSEL is also investigated. This results in the quantitative estimation of lasers with a tunnel junction in terms of device resistance, carrier distribution in the active region and optical absorption loss. The introduction of a tunnel junction may improve the output power, power-conversion efficiency, and mode stability of long-wavelength VCSELs.