We investigated the steady state gamma-ray radiation response of pure-silica-core photonic crystal fibers (PSC-PCFs) under an accumulated dose of 500 Gy and a dose rate of 2.38 Gy/min.The radiation-induced attenuation (RIA) spectra in the near-infrared region from 800 nm to 1700 nm were obtained.We find that the RIA at 1550 nm is related with hydroxyl (OH) absorption defects in addition to the identified self-trapped hole (STH) defects.Moreover,it is proposed and demonstrated that reduced OH absorption defects can decrease the RIA at 1550 nm.The RIA at 1550 nm has effectively declined from 27.7 dB/km to 3.0 dB/km through fabrication improvement.Preliminary explanations based on the unique fabrication processes were given to interpret the RIA characteristics of PSC-PCFs.The results show that the PSC-PCFs,which offer great advantages over conventional fibers,are promising and applicable to fiber sensors in harsh environments.