Realization of optically pumped second-order GaInN-distributed-feedback lasers

Room temperature distributed-feedback (DFB) laser operation is demonstrated with emission wavelengths ranging from 389 to 399 nm. Second-order DFB gratings were defined by electron beam lithography and reactive ion etching in the top GaN barrier layer of a GaInN/GaN double heterostructure grown by metalorganic vapor phase epitaxy. Our data allow a precise determination of the effective refractive index neff(λ) over the whole emission range. neff(λ) is compared with previously published values for GaN and GaInN.