High performance of a semipolar InGaN laser with a phase-shifted embedded hydrogen silsesquioxane (HSQ) grating

Single-frequency blue laser sources are of interest for an increasing number of emerging applications but are still difficult to implement and expensive to fabricate and suffer from poor robustness. Here a novel and universal grating design to realize distributed optical feedback in visible semiconductor laser diodes (LDs) was demonstrated on a semipolar InGaN LD, and its unique effect on the laser performance was investigated. For the first time, to the best of our knowledge, a low threshold voltage, record-high power output, and ultra-narrow single-mode lasing were simultaneously obtained on the new laser structure with a thinner p-GaN layer and a third-order phase-shifted embedded dielectric grating. Under continuous-wave operation, such 450 nm lasers achieved 35 dB side-mode suppression ratio, less than 2 pm FWHM, and near 400 mW total output power at room temperature.