title: Evaluation of thermo-optic characteristics of cryogenically cooled Yb:YAG ceramics.
abstract: The temperature dependence of the thermo-optic effect in cryogenically cooled Yb:YAG ceramics was evaluated by measuring the thermo-optic coefficient (the derivative of refractive index with respect to temperature, i.e., dn/dT), thermal expansion coefficient (α), and thermal conductivity (κ) between 70 and 300 K. These parameters significantly improved at low temperature. Observed values indicated that a laser gain medium cooled to 70 K can sustain a thermal load up to 20 times higher than that at 300 K, for comparable thermo-optic effects. To our best knowledge, this is the first quantitative evaluation of the improvement in thermo-optic characteristics of cryogenically cooled Yb:YAG ceramics.
authors: National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, Gifu 509-5292, Japan. yasuhara@nifs.ac.jp
authors: Ryo
authors: R
authors: Yasuhara
authors: Hiroaki
authors: H
authors: Furuse
authors: Akifumi
authors: A
authors: Iwamoto
authors: Junji
authors: J
authors: Kawanaka
authors: Takagimi
authors: T
authors: Yanagitani