We report the high‐power operation of &lgr;=1.3 &mgr;m InGaAsP double‐channel planar buried‐heterostructure lasers with asymmetric mirror coatings. A stack of four dielectric layers is used to raise the reflectivity of one facet to over 80%, and the thickness of a single layer coating on the output facet is chosen to reduce the reflectivity to about 4%. The resulting lasers are characterized by a low threshold current of 25 mA, slope efficiency as high as 50%, and a power output of as much as 150 mW (at 5 °C) at a current of less than 300 mA. The lasers operate in a single transverse mode over the entire current range and as much as 45 mW of power could be coupled into a lensed single‐mode fiber. Preliminary high‐power aging data show excellent device reliability.