Thermal Lens Compensation of Rod Laser System Inserting a Solid Element with Negative Temperature-Dependence Change of Refractive Index Property

We have successfully demonstrated the compensation of thermal lens effect in Nd: YAG laser rods regardless of pumping condition by inserting a solid-state self-adaptive CE (Compensating Element), having negative dn/dT property between two Nd: YAG rods. Several organic resins and a LiF crystal of higher negative dn/dT which have high damage threshold and low absorbance are very useful to compensate thermal effects in the amplifier. The results revealed that the use of several organic resins resulted in the complete reduction of the thermal lens effect by an order of magnitude. This compensation scheme is an ultimate method because of its dynamic compensation feature independent of the pumping power level.