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Optically Pumped DFB Lasers Based on GaN Using 10th-Order Laterally Coupled Surface Gratings

An optically pumped GaN-based laser structure with 10th-order laterally coupled surface grating is demonstrated. The fabrication involved i-line photolithography and dry etching, avoiding more complex technologies such as multiple epitaxy steps. The lasing threshold of the laterally coupled distributed-feedback (LC-DFB) laser was similar to that of a ridge waveguide Fabry-Perot (RW-FP) laser. Single-peak emission with a full width at half maximum of 0.06 nm at 404.2 nm was achieved for LC-DFB lasers. In contrast to the RW-FP lasers, the LC-DFB laser is shown to exhibit a smaller shift of the emission wavelength with temperature.