The prospects for Yb- and Nd-doped tungstate microchip lasers

Potassium gadolinium and yttrium tungstates doped with trivalent Nd, Yb or Tm ions are widely used crystals for efficient diode-pumped lasers. They are usually oriented along the b crystallographic axis, which is also the N
_p
axis of optical indicatrix. The N
_p
-cut is characterized by a strong thermal lens with opposing signs along N
_m
and N
_g
[1]. This is unsuited to microchip lasers which require a positive thermal lens for a stable cavity. Therefore, a detailed investigation of thermo-optic effects and microchip laser potential of other crystallographic orientations in tungstate crystals is of interest.