A low-loss 1  ×  256 optical power splitter is designed and fabricated using silica-based planar lightwave circuit technology on a 6-in. quartz substrate. The measured results show that the insertion loss, uniformity, and wavelength-dependence loss (WDL) of a 1  ×  256 splitter are <26.2, 1.97, and 1.83 dB, respectively, in the wavelength range from 1.26 to 1.63  μm. The insertion loss, uniformity, and WDL of a 1  ×  256 splitter are <25.62, 1.33, and 1.03 dB, respectively, in the normal communication wavelength range from 1.31 to 1.55μm. The polarization dependence loss is <0.16  dB in the wavelengths of 1.31 and 1.55  μm.