An asymmetric large optical cavity (LOC) waveguide is designed to raise the output power of the 940 nm laser diode. By optimizing the metal organic chemical vapor deposition growth condition and combining with the electrode fabrication and facet coating, single emitter semiconductor laser diodes of 95 mm strip width and 4 mm cavity length are fabricated. Without any active cooling process, an output power of 13.4 W is reached at 15 A injection current without catastrophic optical mirror damage at room temperature. By introducing the asymmetric LOC waveguide, the far-field test shows that only the transverse fundamental mode is lased with a vertical far-field angle full width of half magnitude of 22o.