Epitaxial strategy for high-polarization semiconductor lasers with process robustness

We demonstrate an epitaxial strategy for improving the degree of polarization (DoP) of semiconductor lasers under packaging-induced stress by increasing the intrinsic TE/TM effective refractive-index difference, n_diff⁰. Three distinct epitaxial structures with n_diff⁰ values of 4.75 × 10^-4, 9.09 × 10^-4, and 1.24 × 10^-3 were designed and fabricated. At 14 A, the measured DoP increased from 90.2% to 97.3% with increasing n_diff⁰. Structures with larger n_diff⁰ also exhibited lower sensitivity to packaging-induced stress variations. These results show that engineering n_diff⁰ through epitaxial design provides a practical route toward process-robust high-polarization semiconductor lasers.