Magnetic circular polarization of luminescence in bismuth-doped silica glass

Abstract

Bismuth-doped-silica-based optical fibers as a laser gain medium covers the spectral regions inaccessible to conventional rare-earth-doped fibers. Unfortunately, the nature of the luminescent centers in these fibers is not well understood, which complicates the development of efficient devices. In this Letter the magnetic-field-induced circular polarization of near-infrared (NIR) photoluminescence (PL) in Bi-doped pure silica glass was studied in the spectral range of 660–1600 nm, covering three excited state levels. The results of variable temperature and magnetic field measurements allow concluding that the NIR PL originates from an isolated non-Kramers doublet of the even-electron system. This result significantly narrows the list of possible origins of NIR PL in Bi-doped silica glasses.