An asymmetric super large optical cavity waveguide is designed to realize the high output power semiconductor laser, in which the super large optical cavity is used to raise the catastrophic optical mirror damage (COMD) limit, and the asymmetric waveguide is used to inhibit the lasing of higher order modes. Meanwhile, the optimized thickness of the asymmetric waveguide is analyzed. By optimizing the process condition of metal organic chemical vapor disposition (MOCVD) epitaxy for the active layer, and combining with the electrode fabrication and facet coating, a 4-mm cavity length semiconductor laser die with 2 μm super large optical cavity waveguide at 980 nm wavelength is fabricated. Without any active cooling process, an output power of 23.6 W is reached with injection current of 30 A without COMD at room temperature. Because of the introducing of the super large optical cavity waveguide, the far field test shows that only the transverse fundamental mode is lased with a vertical far field angle of 24°. The results show that the asymmetric super large optical cavity structure is an effective way to get the high output power of semiconductor laser.