Determination of the thermo-optic coefficient dn/dT of ytterbium doped ceramics (Sc2O3, Y2O3, Lu2O3, YAG), crystals (YAG, CaF2) and neodymium doped phosphate glass at cryogenic temperature

In this paper, we report the measurements of the thermal expansion coefficient and the thermo-optic coefficient dn/dT for the ytterbium doped cubic sesquioxides (Sc2O3, Y2O3, Lu2O3) at cryogenic temperature. These materials appear to have very interesting properties for setting up high average power laser chains useful for plasma physics and for inertial fusion energy drivers. Measurements have also been done on YAG ceramic and crystal, CaF2 crystal, and neodymium phosphate glass (Hoya, LHG-8).

► Thermal expansion and thermo-optic coefficients at 633 nm of Yb-doped sesquioxide ceramics as a function of temperature.
► Same measurements on undoped and Yb-doped YAG CaF2 crystals and Nd-doped phosphate glass.
► When temperature decreases thermal expansion coefficients and absolute values of the thermo-optic coefficients decrease.
► No dependence of the thermal expansion and the thermo-optic coefficients with the doping levels.
► First measurements of the thermo-optic coefficients of lutetia and scandia. Scandia coefficient is negative.