• Ito, Hiroshi
• Ohishi, Y.
• Hasegawa, Kazuo
• Hughes, Mark A.
• Suzuki, T.
• Mizuno, S.
• Nasu, Hiroyuki

Abstract

The efficiency of energy transfer from Cr to Nd in silicate glasses has been examined in order to develop a gain medium for high-efficiency solar pumped fiber lasers (SPFLs). The internal quantum efficiency (QE) of the emission from the 4T2 state of Cr in Cr-doped glasses and from the 4F3/2 state of Nd in Nd-doped and Nd,Cr codoped glasses was measured using an integrating sphere. For Cr-doped and Nd,Cr codoped glasses, 650 nm excitation was used. For Nd-doped glasses, 808 nm excitation was used. The QE of Cr-doped glass (η Cr) was 7.5 % for 0.05 mol.% Cr2O3, the QE decreased monotonically with increasing Cr2O3 content. The QE of the Nd-doped glass (η Nd) has a maximum of 43% at 0.2 mol.% Nd2O3. We suggest that absorption of host glass could lower the QE at the low content side of the maximum. The QE of Nd emission in Nd,Cr codoped glass (η Nd,Cr) excited at 650 nm, which excites the 4A2→4T2 transition of Cr was 5.7 % for 0.05 mol.% Cr2O3 and 0.2 mol.% Nd2O3 content. The energy transfer quantum efficiency, η tr, from Cr to Nd which is defined as the ratio of the η Cr and the η Nd,Cr was calculated from the obtained QEs. The largest η tr was 13.4 % at 0.01 mol.% Cr2O3, and decreased with increasing Cr2O3 when content of Nd2O3 was fixed by 0.2 mol.%. This tendency is quite similar to the QEs of the Cr emission in Cr-doped glasses. Thus an increase in the QE of Cr maybe essential to increase the η tr.

Topics

• impedance spectroscopy
• glass
• glass