Non-uniform well-thickness multi-quantum wells materials were adopted to widen the output spectrum of superluminescent diodes. 850 nm high-power, wide-spectrum, low-divergence superluminescent diodes with large optical cavity structure were fabricated. The spectral width (FWHM) of 26 nm, continuous wave (CW) output power of 6 mW were achieved at operating current of 120 mA. The pigtail output power when coupled with single-mode polarization maintaining fiber reached 1.0 mW.