Thermal lensing in Er, Yb : YVO4 crystal

Abstract

A thermal lens is characterized in 0.7 at.%Er, 3 at.%Yb : YVO4 yttrium vanadate crystal cut along the [1 0 0] crystallographic axis, for π and σ laser polarizations, by a probe beam method. For a pump spot radius of 100 μm and π-polarization, sensitivity factors of the thermal lens equal 5.7 and 7.9 m−1 W−1 (parallel and perpendicular to the [0 0 1]-axis, respectively); the astigmatism degree is 28%. The fractional heat load is determined by ISO-standard laser calorimetry, ηh = 0.63 ± 0.05. The anisotropy of the photo-elastic effect plays a dominant role in the formation of the astigmatic thermal lens.