Preparation and spectral characteristics of Bi-doped double cladding fiber
双包层掺Bi光纤的制备及其光谱特性研究

Bi-doped double cladding fiber preform is prepared by modified chemical vapor deposition and solution doping process.The absorption spectrum of preform and the near-infrared(NIR) luminescence spectrum of fiber are experimentally investigated.The luminescence spectrum of the fiber shows a peak emission band at 1140 nm with a full-width at half-maximum(FWHM) of 130 nm under 976 nm LD exciting.Under 808 or 793 nm LD exciting,an ultra-broad NIR emission with an FWHM of more than 250 nm is observed in the Bi-doped fiber,and the range of luminescence spectrum is from 1000 to 1700 nm.After the heat treatment of the Bi-doped fiber preform slice under 900°C for 1 h,under 808 nm LD exciting,the fluorescence intensity is about 4 times higher than that of the perform slice without heat treatment.The results indicate that the Bi-doped double cladding fiber is a promising gain medium used for ultrashort fiber lasers and tunable fiber lasers.