This paper reports a broad-area distributed feedback(DFB) laser with surface second-order metal grating,based on the holographic photolithography and wet etching technology without epitaxial regrowth process after the grating fabrication.At room temperature,for the uncoated device with a cavity length of 1 mm,the stable longitudinal single-mode emission around 927 nm has been achieved in a large current range.In pulsed operation,at a current of 2.28 A,the front facet output power is above 600 mW...