Abstract

The applications of ultrafast lasers requires, besides a wide gain spectrum and high quantum efficiency, high average power and high reliability of laser operation. One of the most promising solutions for high-power all solid-state laser working in the picoseconds range is Yb:YAG laser.¹ Yb:YAG material has a very low quantum defect (8.6%), long storage lifetime (951 μs) and a large gain spectrum. Tunability of 85-nm in Yb:YAG at room temperature have been demonstrated.^2,3 Various schemes were used to operate efficiently this active medium, including zig-zag slab,⁴ end- pumped microchip,⁵ thin disc⁶ or rod⁷ geometry. The beam quality can be improved by using thin disc crystals because of the orientation of the heat flux collinearly with the direction of laser propagation. More than 1.5 kW output power with optical efficiency in excess of 56% were obtained from the end-pumped thin disc configuration.⁶ Recently a composite Yb:YAG microchip scheme that consists of an Yb doped core surrounded by an undoped YAG of slab or disk shape and that is radial pumped was proposed⁸ In this work we report first experimentally results obtained on a composite 2-at.% Yb:YAG microchip laser radially pumped by diode lasers at 941 nm. CW laser emission with 50% slope efficiency and 1.8 W maximum output power for 5.1 W absorbed power is demonstrated.

© 2002 Optical Society of America