Traditional diode lasers typically suffer from large divergence angles and multi-mode operation at high power output, which limits their beam focusing capability and stability. This study employs a Littman-type external cavity diode laser structural model combined with classical multi-beam interference theory. A tapered diode laser is integrated with external optical components, including a transmission grating, a prism, and a flat mirror, to design and construct an external cavity diode laser capable of high beam quality and narrow linewidth laser output. When the wavelength is locked at 976 nm, the laser achieves an output power of 1.48 W, with a fast-axis beam quality factor of Mx2=1.41 and a slow-axis beam quality factor of My2=1.39. The linewidth is compressed from 10 nm in free-running operation to 0.24 nm. This laser exhibits high output power, excellent beam quality, and narrow linewidth characteristics, making it an ideal pump source for solid-state and fiber laser applications.