III-Nitride Based VCSEL with Curved Mirror on P-Side of the Aperture

Conventional planar mirrors used in vertical-cavity surface-emitting lasers (VCSELs) suffer from more diffraction loss the longer they become. However, the length of the cavity that is formed by these mirrors can also provide advantages such as tighter mode spacing and better thermal management. There is a need for devices that can realize the advantages of longer cavities while avoiding the diffraction loss that typically accompanies them.

Researchers at the University of California, Santa Barbara have incorporated a curved mirror formed above the p-side of a III-nitride VCSEL to minimize diffraction loss and extend the lifetime and reliability of the device. When using a curved mirror, the reflected light can be focused back into the center of the aperture, thus minimizing diffraction loss. The curved mirror also affords the use of a long cavity, allowing for better thermal management and significant reduction of thermal rollover, thus increasing lifetime and reliability of the VCSEL. Additionally, the tight mode spacing of this technology allows for a greater tolerance of the cavity length, which increases the yield during device growth and fabrication.