Efficient Energy Transfer of Cr3+ to Nd3+ in Transparent Ceramics Composite Rod for Solar-pumped Laser

We have proposed a new configuration of a solar-pumped laser employing a transparent ceramics rod. The laser has a composite structure consisting of a Nd/Cr:YAG gain rod surrounded by Gd:YAG non-gain parts with the same refractive index as Nd/Cr:YAG. The lasing mode is controlled only by output coupler, and parasitic oscillation is suppressed. In the laser rod, Nd3+ laser oscillation was realized by directly exciting Cr3+ at a wavelength of 635 nm. It was confirmed that the slope efficiency of the laser output due to heat generation was reduced. The energy transfer efficiency from Cr3+ to Nd3+ was estimated to be 71.5% from the laser oscillation characteristics in the state without thermal effect.