In this letter a 1 060 mm distributed feedback laser with an optimized double-trench ridge waveguide structure is presented. The lateral mode stability is strongly improved under continuous-wave operating condition. The maximum single spectral and spatial mode output power is approximately 300 mW with a side mode suppression ratio larger than 45 dB. The capability of the device for green light generation is also demonstrated experimentally by pumping a periodically poled lithium niobate waveguide crystal, which the power of the green light is about 3 mW.