THERMAL LENSING MEASUREMENTS IN LINE-FOCUS END-PUMPED NEODYMIUM YTTRIUM-ALUMINUM-GARNET USING HOLOGRAPHIC LATERAL SHEARING INTERFEROMETRY

Thermal lensing in compact neodymium yttrium aluminium garnet slabs an d rods end pumped with a beam brought to a line focus has been measure d using holographic lateral shearing interferometry. This powerful tec hnique enabled us to directly measure thermal lenses with focal length s in the range 0.02-12 m with an accuracy of 12% and good spatial reso lution. It was found that the Line focused pump beam resulted in sever e astigmatic thermal lensing. The measured thermal lens strongly devia ted from the ideal parabolic profile along both axes, introducing an i mportant additional consideration for laser-diode end-pumped laser res onator design. The degree of longitudinal heat flow was found to stron gly influence thermal lens power. It is anticipated that results obtai ned from the measurement technique presented here will enable optimal design of high-power end-pumped solid-state laser cavities. (C) 1998 A merican Institute of Physics.