A high-power single-longitudinal-mode regrowth-free tapered gain-coupled distributed feedback laser diode based on periodic current injection is achieved at 996 nm. It enhances the output power without beam quality degrading. A continuous-wave output power of over 1.12 W is achieved at 3 A. The maximum output power in single-longitudinal-mode operation is up to 0.56 W at 1.4 A. The power conversion efficiency is over 24%, and the slope efficiency is 0.58 W/A. The side mode suppression ratio is over 38 dB; the 3 dB spectral linewidth is less than 2.4 pm. The lateral far-field divergence angle is only 14.98°, and the beam quality factor M2 is 1.64, achieving a near-diffraction-limit emission. Our device has great potential in commercial applications and the experimental study of high-power near-diffraction-limit laser diodes for its low-cost fabrication technique and narrowband single-longitudinal-mode emission at high power.