title: Faraday rotation and photoluminescence in heavily Tb(3+)-doped GeO2-B2O3-Al2O3-Ga2O3 glasses for fiber-integrated magneto-optics.
abstract: We report on the magneto-optical (MO) properties of heavily Tb(3+)-doped GeO2-B2O3-Al2O3-Ga2O3 glasses towards fiber-integrated paramagnetic MO devices. For a Tb(3+) ion concentration of up to 9.7 × 10(21) cm(-3), the reported glass exhibits an absolute negative Faraday rotation of ~120 rad/T/m at 632.8 nm. The optimum spectral ratio between Verdet constant and light transmittance over the spectral window of 400-1500 nm is found for a Tb(3+) concentration of ~6.5 × 10(21) cm(-3). For this glass, the crystallization stability, expressed as the difference between glass transition temperature and onset temperature of melt crystallization exceeds 100 K, which is a prerequisite for fiber drawing. In addition, a high activation energy of crystallization is achieved at this composition. Optical absorption occurs in the NUV and blue spectral region, accompanied by Tb(3+) photoluminescence. In the heavily doped materials, a UV/blue-to-green photo-conversion gain of ~43% is achieved. The lifetime of photoluminescence is ~2.2 ms at a stimulated emission cross-section σem of ~1.1 × 10(-21) cm(2) for ~ 5.0 × 10(21) cm(-3) Tb(3+). This results in an optical gain parameter σem*τ of ~2.5 × 10(-24) cm(2)s, what could be of interest for implementation of a Tb(3+) fiber laser.
authors.affiliation: Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany.
authors.forename: Guojun
authors.initials: G
authors.lastname: Gao
authors.affiliation: Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Winterstein-Beckmann
authors.affiliation: Innovent e.V., 07745 Jena, Germany.
authors.forename: Oleksii
authors.initials: O
authors.lastname: Surzhenko
authors.affiliation: Innovent e.V., 07745 Jena, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Dubs
authors.affiliation: Leibniz Institute of Photonic Technology, 07745 Jena, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Dellith
authors.affiliation: Leibniz Institute of Photonic Technology, 07745 Jena, Germany.
authors.forename: Markus A
authors.initials: MA
authors.lastname: Schmidt
authors.affiliation: Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Wondraczek