Thermal and optical properties of tellurite glasses doped erbium

Thermal and Optical Studies of Rare Earth Doped Tungston–Tellurite Glasses

“…The E opt values with an accuracy of +_0.01 eV obtained by extrapolation to (αhυ) 2 = 0 for indirect allowed transitions and (αhυ) 1/2 = 0 for direct allowed transitions. The values of E opt for indirect and direct allowed transitions are given in Table (1).Its value shows that these glasses have direct band gap since the value of E opt for indirect band gap exceeds the value of E opt for direct band gap [13].…”

“…The reduction of band gap after rare earth doping is attributed to the structural changes that are taking place in the glass with the incorporation of rare earth elements which act as the modifiers . The study of variation of optical band gap with Er 2 O 3 and Gd 2 O 3 composition gives information regarding the structure and the nature of bonds [13]. All values are given in Table I, Fig.…”

“…When rare earth is introduced into the Tellurite matrix, its coordination number changes. The optical band gap is influenced not only by a chemical composition but also by a structural arrangement of the sample matrix [13]. When Er 2 O 3 is replaced by Gd 2 O 3 the increase in optical band gap is due to the replacement of Er-O bond by Gd-O bond.…”

“…The increase in optical band gap with Gd 2 O 3 content can be explained with the movement of electron density [15]. When Gd 2 O 3 is added instead of Er 2 O 3 in the samples the number of Non-Bridging Oxygen decreases which accordingly increases the optical band gap [13]. The reduction in the number of Non-Bridging Oxygen is due to the value of molar mass of the materials.…”

Optical and Thermal Properties of Some Tellurite Glasses

“…Recently, the absorption spectrum fitting method (ASF) and derivation of absorption spectrum fitting (DASF) methods have been introduced to obtain the band gap avoiding the film thickness measurement which commonly could not be measured precisely [13,14]. Also, tellurite glasses with high thermal and glass stabilities were suggested as potential materials to realize highly efficient fibers [15][16][17][18][19][20].…”