A Dual-Crystal Cavity Ho,Tm:GdVO₄ Laser

We report a 31.2 W cw diode-pumped cryogenic Ho(0.4at.%),Tm(4at.%):GdVO₄ laser in a dual−crystal cavity. The pumping sources are two fiber-coupled laser diodes with a fiber core diameter of 0.4 mm, both of which can supply 42 W near 802 nm. With an incident pump power of 70.3 W at 802.4 nm, a cw output power of 31.2 W at 2.05 µm is attained, corresponding to an optical−to-optical conversion efficiency of 44.4%. The M² factor is measured as ∼1.3 under an output power of 20 W.