Thermal Focal Length Control in Passively Q-switched End Pulsed-Pumped Ceramics and Single Crystal Yb3+:YAG/ Cr4+:YAG Microchip Laser
J. M. El-Azab, Y. S. Nada and S. M. Maize
Different thermal lens focal lengths with different pumping repetition rates for ceramic and single crystal Yb: YAG are calculated in order to control the thermal focal length without using additional optical elements. The effect of pumping energy and pump beam diameter on the thermal focal length is studied and it is found that the thermal focal length decreases with the increasing of pump energy and it decreases with the increasing of pump beam diameter. Finally, the stability of the cavity is investigated via an ABCD matrix method which shows that ceramic laser with lower thermal focal length has more stability than single crystal with higher thermal focal length.
Keywords: Q-Switched Laser, Microchip Laser, Thermal Lens, ABCD Matrix, ceramic laser.