Influences of Ridge-Waveguide Shape and Width on Performances of InP-Based Coupled Ridge-Waveguide Laser Arrays

We investigate the influences of ridge-waveguide shape and width on performances of InP-based coupled ridge waveguide laser arrays emitting at
$2.1~\mu \text{m}$
. Four devices with different shapes and widths of ridge elements are fabricated. The trapezoid ridges reduce the optical losses at regions between ridge elements in the trapezoid devices, thus enhances the optical coupling between ridge elements and lead to larger coherent output powers compared with the rectangular ones. Meanwhile, narrower ridges with the same shape give a stronger optical confinement to the lateral modes in every single ridge and improve the overall modal and far-field characteristics of the device. The results show that the trapezoid and narrower ridges can lead to a comprehensive improvement in the performances of the coupled ridge waveguide laser arrays emitting at
$2.1~\mu \text{m}$
.